Fix finiterectlat-modes.py obvious errors.

Former-commit-id: a538ed6c3c84cebffccd41272994027039e46b57

CMakeLists.txt

@@ -5,8 +5,6 @@ include(GNUInstallDirs)
 
 project (QPMS)
 
-set(CMAKE_BUILD_TYPE Debug)
-
 macro(use_c99)
   if (CMAKE_VERSION VERSION_LESS "3.1")
     if (CMAKE_C_COMPILER_ID STREQUAL "GNU")

misc/finiterectlat-modes.py

@@ -0,0 +1,122 @@
+#!/usr/bin/env python3
+
+import math
+from qpms.argproc import ArgParser
+
+
+ap = ArgParser(['rectlattice2d_finite', 'single_particle', 'single_lMax', ])
+
+ap.add_argument("-t", "--rank-tolerance", type=float, default=1e11)
+ap.add_argument("-c", "--min-candidates", type=int, default=1, help='always try at least this many eigenvalue candidates, even if their SVs in the rank tests are lower than rank_tolerance')
+ap.add_argument("-T", "--residual-tolerance", type=float, default=0.)
+
+ap.add_argument("-o", "--output", type=str, required=False, help='output path (if not provided, will be generated automatically)')
+#ap.add_argument("-O", "--plot-out", type=str, required=False, help="path to plot output (optional)")
+#ap.add_argument("-P", "--plot", action='store_true', help="if -p not given, plot to a default path")
+#ap.add_argument("-g", "--save-gradually", action='store_true', help="saves the partial result after computing each irrep")
+
+ap.add_argument("-f", "--centre", type=complex, required=True, help='Contour centre in eV')
+ap.add_argument("--ai", type=float, default=0.05, help="Contour imaginary half-axis in eV")
+ap.add_argument("--ar", type=float, default=0.05, help="Contour real half-axis in eV")
+ap.add_argument("-N", type=int, default="150", help="Integration contour discretisation size")
+
+ap.add_argument("--irrep", type=str, default="none", help="Irrep subspace (irrep index from 0 to 7, irrep label, or 'none' for no irrep decomposition")
+
+a=ap.parse_args()
+
+import logging
+logging.basicConfig(format='%(asctime)s %(message)s', level=logging.INFO)
+
+Nx, Ny = a.size
+px, py = a.period
+
+particlestr = ("sph" if a.height is None else "cyl") + ("_r%gnm" % (a.radius*1e9))
+if a.height is not None: particlestr += "_h%gnm" % (a.height * 1e9)
+defaultprefix = "%s_p%gnmx%gnm_%dx%d_m%s_n%g_L%d_c(%s±%g±%gj)eV_cn%d" % (
+    particlestr, px*1e9, py*1e9, Nx, Ny, str(a.material), a.refractive_index, a.lMax,
+    str(a.centre), a.ai, a.ar, a.N)
+logging.info("Default file prefix: %s" % defaultprefix)
+
+def inside_ellipse(point_xy, centre_xy, halfaxes_xy):
+    x = point_xy[0] - centre_xy[0]
+    y = point_xy[1] - centre_xy[1]
+    ax = halfaxes_xy[0]
+    ay = halfaxes_xy[1]
+    return ((x/ax)**2 + (y/ay)**2) <= 1
+
+
+import numpy as np
+import qpms
+from qpms.cybspec import BaseSpec
+from qpms.cytmatrices import CTMatrix, TMatrixGenerator
+from qpms.qpms_c import Particle
+from qpms.cymaterials import EpsMu, EpsMuGenerator, LorentzDrudeModel, lorentz_drude
+from qpms.cycommon import DebugFlags, dbgmsg_enable
+from qpms import FinitePointGroup, ScatteringSystem, BesselType, eV, hbar
+from qpms.symmetries import point_group_info
+eh = eV/hbar
+
+dbgmsg_enable(DebugFlags.INTEGRATION)
+
+#Particle positions
+orig_x = (np.arange(Nx/2) + (0 if (Nx % 2) else .5)) * px
+orig_y = (np.arange(Ny/2) + (0 if (Ny % 2) else .5)) * py
+
+orig_xy = np.stack(np.meshgrid(orig_x, orig_y), axis = -1)
+
+
+bspec = BaseSpec(lMax = a.lMax)
+medium = EpsMuGenerator(ap.background_epsmu)
+particles= [Particle(orig_xy[i], ap.tmgen, bspec) for i in np.ndindex(orig_xy.shape[:-1])]
+
+sym = FinitePointGroup(point_group_info['D2h'])
+logging.info("Creating scattering system object")
+ss, ssw = ScatteringSystem.create(particles, medium, sym, a.centre * eh)
+
+if a.irrep == 'none':
+    iri = None # no irrep decomposition
+    irname = 'full'
+    logging.info("Not performing irrep decomposition and working with the full space of dimension %d." % ss.fecv_size)
+else:
+    try:
+        iri = int(a.irrep)
+    except ValueError:
+        iri = ss.irrep_names.index(a.irrep)
+    irname = ss.irrep_names[iri]
+    logging.info("Using irrep subspace %s (iri = %d) of dimension %d." % (irname, iri, ss.saecv_sizes[iri]))
+
+outfile_tmp = defaultprefix + ".tmp" if a.output is None else a.output + ".tmp"
+
+logging.info("Starting Beyn's algorithm")
+results = ss.find_modes(iri=iri, omega_centre = a.centre*eh, omega_rr=a.ar*eh, omega_ri=a.ai*eh, contour_points=a.N,
+        rank_tol=a.rank_tolerance, rank_min_sel=a.min_candidates, res_tol=a.residual_tolerance)
+results['inside_contour'] = inside_ellipse((results['eigval'].real, results['eigval'].imag),
+        (a.centre.real*eh, a.centre.imag*eh), (a.ar*eh, a.ai*eh))
+results['refractive_index_internal'] = [medium(om).n for om in results['eigval']]
+
+outfile = defaultprefix + (('_ir%s_%s.npz' % (str(iri), irname)) if iri is not None else '.npz') if a.output is None else a.output
+np.savez(outfile, meta=vars(a), **results)
+logging.info("Saved to %s" % outfile)
+
+exit(0)
+
+# TODO plots.
+if a.plot or (a.plot_out is not None):
+    import matplotlib
+    matplotlib.use('pdf')
+    from matplotlib import pyplot as plt
+
+    fig = plt.figure()
+    ax = fig.add_subplot(111)
+    ax.plot(sinalpha_list, σ_ext*1e12,label='$\sigma_\mathrm{ext}$')
+    ax.plot(sinalpha_list, σ_scat*1e12, label='$\sigma_\mathrm{scat}$')
+    ax.plot(sinalpha_list, σ_abs*1e12, label='$\sigma_\mathrm{abs}$')
+    ax.legend()
+    ax.set_xlabel('$\sin\\alpha$')
+    ax.set_ylabel('$\sigma/\mathrm{\mu m^2}$')
+    
+    plotfile = defaultprefix + ".pdf" if a.plot_out is None else a.plot_out
+    fig.savefig(plotfile)
+
+exit(0)
+

qpms/CMakeLists.txt

@@ -15,7 +15,7 @@ add_library (qpms SHARED translations.c tmatrices.c vecprint.c vswf.c wigner.c e
 	ewaldsf.c pointgroups.c latticegens.c
 	lattices2d.c gaunt.c error.c legendre.c symmetries.c vecprint.c
 	bessel.c own_zgemm.c parsing.c scatsystem.c materials.c drudeparam_data.c
-	lll.c beyn.c
+	lll.c beyn.c scatsys_translation_booster.c
 	)
 use_c99()
 
@@ -31,7 +31,7 @@ target_include_directories (qpms PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
 
 target_compile_options(qpms PRIVATE -Wall -Wno-return-type -Wno-unused-variable -Wno-unused-function -Wno-unused-but-set-variable -Wno-unused-label)
 target_compile_definitions(qpms PRIVATE LATTICESUMS32 QPMS_VECTORS_NICE_TRANSFORMATIONS
-	EWALD_AUTO_CUTOFF
+	EWALD_AUTO_CUTOFF QPMS_EVALUATE_PARANOID_ASSERTS
 	)
 
 install(TARGETS qpms

qpms/__init__.py

@@ -7,7 +7,7 @@ from sys import platform as __platform
 import warnings as __warnings
 
 try:
-    from .qpms_c import PointGroup, FinitePointGroup, FinitePointGroupElement, Particle, scatsystem_set_nthreads, ScatteringSystem, ScatteringMatrix, pitau, set_gsl_pythonic_error_handling, pgsl_ignore_error, gamma_inc, lll_reduce
+    from .qpms_c import PointGroup, FinitePointGroup, FinitePointGroupElement, Particle, scatsystem_set_nthreads, ScatteringSystem, ScatteringMatrix, pitau, set_gsl_pythonic_error_handling, pgsl_ignore_error, gamma_inc, lll_reduce, ScatteringSystemCachingMode
 except ImportError as ex:
     if __platform == "linux" or __platform == "linux2":
         if 'LD_LIBRARY_PATH' not in __os.environ.keys():

qpms/beyn.c

@@ -345,7 +345,7 @@ void BeynSolver_srandom(BeynSolver *solver, unsigned int RandSeed)
 static int beyn_process_matrices(BeynSolver *solver, beyn_function_M_gsl_t M_function, 
     void *Params,
     gsl_matrix_complex *A0, gsl_matrix_complex *A1, double complex z0,
-    gsl_vector_complex *eigenvalues, gsl_matrix_complex *eigenvectors, const double rank_tol, const double res_tol)
+    gsl_vector_complex *eigenvalues, gsl_matrix_complex *eigenvectors, const double rank_tol, size_t rank_sel_min, const double res_tol)
 {
   const size_t m = solver->M;
   const size_t l = solver->L;
@@ -379,7 +379,7 @@ static int beyn_process_matrices(BeynSolver *solver, beyn_function_M_gsl_t M_fun
   int K=0;
   for (int k=0; k<Sigma->size /* this is l, actually */; k++) { 
     if (verbose) printf("Beyn: SV(%d)=%e\n",k,gsl_vector_get(Sigma, k));
-    if (gsl_vector_get(Sigma, k) > rank_tol)
+    if (k < rank_sel_min || gsl_vector_get(Sigma, k) > rank_tol)
       K++;
   }
   if (verbose)printf(" Beyn: %d/%zd relevant singular values\n",K,l);
@@ -494,7 +494,7 @@ static int beyn_process_matrices(BeynSolver *solver, beyn_function_M_gsl_t M_fun
 
     gsl_vector_complex_set(eigenvalues, KRetained, zgsl);
     if(eigenvectors) {
-      gsl_matrix_complex_set_col(eigenvectors, KRetained, &(Vk.vector));
+      gsl_matrix_complex_set_row(eigenvectors, KRetained, &(Vk.vector));
       gsl_vector_set(solver->residuals, KRetained, residual);
     }
     ++KRetained;
@@ -513,7 +513,7 @@ static int beyn_process_matrices(BeynSolver *solver, beyn_function_M_gsl_t M_fun
 beyn_result_gsl_t *beyn_solve_gsl(const size_t m, const size_t l,
     beyn_function_M_gsl_t M_function, beyn_function_M_inv_Vhat_gsl_t M_inv_Vhat_function,
     void *params, const beyn_contour_t *contour,
-    double rank_tol, double res_tol)
+    double rank_tol, size_t rank_sel_min, double res_tol)
 {  
   BeynSolver *solver = BeynSolver_create(m, l);
 
@@ -583,14 +583,14 @@ beyn_result_gsl_t *beyn_solve_gsl(const size_t m, const size_t l,
   gsl_vector_complex *eigenvalue_errors     = solver->eigenvalue_errors;
   gsl_matrix_complex *eigenvectors = solver->eigenvectors;
 
-  // Beyn Steps 3–6
-  int K = beyn_process_matrices(solver, M_function, params, A0, A1, z0, eigenvalues, eigenvectors, rank_tol, res_tol);
   // Repeat Steps 3–6 with rougher contour approximation to get an error estimate.
-  int K_coarse = beyn_process_matrices(solver, M_function, params, A0_coarse, A1_coarse, z0, eigenvalue_errors, eigenvectors, rank_tol, res_tol);
-
-  gsl_blas_zaxpy(gsl_complex_rect(-1,0), eigenvalues, eigenvalue_errors);
+  int K_coarse = beyn_process_matrices(solver, M_function, params, A0_coarse, A1_coarse, z0, eigenvalue_errors, /*eigenvectors_coarse*/ NULL, rank_tol, rank_sel_min, res_tol);
   // Reid did also fabs on the complex and real parts ^^^.
 
+  // Beyn Steps 3–6
+  int K = beyn_process_matrices(solver, M_function, params, A0, A1, z0, eigenvalues, eigenvectors, rank_tol, rank_sel_min, res_tol);
+  gsl_blas_zaxpy(gsl_complex_rect(-1,0), eigenvalues, eigenvalue_errors);
+
   beyn_result_gsl_t *result;
   QPMS_CRASHING_MALLOC(result, sizeof(beyn_result_gsl_t));
   result->eigval = solver->eigenvalues;
@@ -636,12 +636,12 @@ static int beyn_function_M_inv_Vhat_carr2gsl(gsl_matrix_complex *target,
 }
 
 beyn_result_t *beyn_solve(size_t m, size_t l, beyn_function_M_t M, beyn_function_M_inv_Vhat_t M_inv_Vhat,
-    void *params, const beyn_contour_t *contour, double rank_tol, double res_tol) {
+    void *params, const beyn_contour_t *contour, double rank_tol, size_t rank_sel_min, double res_tol) {
   struct beyn_function_M_carr2gsl_param p = {M, M_inv_Vhat, params};
   return beyn_result_from_beyn_result_gsl(
     beyn_solve_gsl(m, l, beyn_function_M_carr2gsl,
       (p.M_inv_Vhat_function) ? beyn_function_M_inv_Vhat_carr2gsl : NULL, 
-      (void *) &p, contour, rank_tol, res_tol)
+      (void *) &p, contour, rank_tol, rank_sel_min, res_tol)
     );
 }
 

qpms/beyn.h

@@ -72,7 +72,7 @@ typedef struct beyn_result_gsl_t {
 	gsl_vector_complex *eigval;
 	gsl_vector_complex *eigval_err;
 	gsl_vector *residuals;
-	gsl_matrix_complex *eigvec;
+	gsl_matrix_complex *eigvec; // Rows are the eigenvectors
 	gsl_vector *ranktest_SV;
 } beyn_result_gsl_t;
 
@@ -85,7 +85,7 @@ typedef struct beyn_result_t {
 	complex double *eigval;
 	complex double *eigval_err;
 	double *residuals;
-	complex double *eigvec;
+	complex double *eigvec; // Rows are the eigenvectors
 	double *ranktest_SV;
 
 	/// Private, we wrap it around beyn_result_gsl_t for now.
@@ -109,6 +109,7 @@ beyn_result_gsl_t *beyn_solve_gsl(
 		void *params, ///< Parameter pointer passed to M() and M_inv_Vhat().
 		const beyn_contour_t *contour, ///< Integration contour.
 		double rank_tol, ///< (default: `1e-4`) TODO DOC.
+		size_t rank_min_sel, ///< Minimum number of eigenvalue candidates, even if they don't pass \a rank_tol.
 		double res_tol ///< (default: `0.0`) TODO DOC.
 	      );
 
@@ -120,6 +121,7 @@ beyn_result_t *beyn_solve(
 		void *params, ///< Parameter pointer passed to M() and M_inv_Vhat().
 		const beyn_contour_t *contour, ///< Integration contour.
 		double rank_tol, ///< (default: `1e-4`) TODO DOC.
+		size_t rank_min_sel, ///< Minimum number of eigenvalue candidates, even if they don't pass \a rank_tol.
 		double res_tol ///< (default: `0.0`) TODO DOC.
 	      );
 

qpms/groups.h

@@ -81,6 +81,12 @@ static inline qpms_gmi_t qpms_finite_group_inv(const qpms_finite_group_t *G,
 	return G->invi[a];
 }
 
+static inline _Bool qpms_iri_is_valid(const qpms_finite_group_t *G, qpms_iri_t iri) {
+	return (iri > G->nirreps || iri < 0) ? 0 : 1;
+}
+
+
+
 /// NOT IMPLEMENTED Get irrep index by name.
 qpms_iri_t qpms_finite_group_find_irrep_by_name(qpms_finite_group_t *G, char *name);
 

qpms/optim.h

@@ -19,4 +19,10 @@
 #define QPMS_EXPECT(exp,c) (exp)
 #endif
 
+#if (defined(__GNUC__) && __GNUC__ >= 3) || \
+    (defined(__GNUC__) && defined(__GNUC_MINOR__) && __GNUC__ == 2 && __GNUC_MINOR__ >= 8) 
+// TODO clang
+#define QPMS_NORETURN __attribute__((noreturn))
+#endif
+
 #endif // OPTIM_H

qpms/qpms_c.pyx

@@ -16,7 +16,7 @@ from .cytmatrices cimport CTMatrix, TMatrixFunction, TMatrixGenerator
 from .cymaterials cimport EpsMuGenerator
 from libc.stdlib cimport malloc, free, calloc
 import warnings
-
+import enum
 
 # Set custom GSL error handler. N.B. this is obviously not thread-safe.
 cdef char *pgsl_err_reason
@@ -280,7 +280,7 @@ cdef class Particle:
             if isinstance(tgen.holder, CTMatrix):
                 spec = (<CTMatrix>tgen.holder).spec
             else:
-                raise ValueError("bspec argument must be specified separately for str(type(t))")
+                raise ValueError("bspec argument must be specified separately for %s" % str(type(t)))
         self.f = TMatrixFunction(tgen, spec)
         self.p.tmg = self.f.rawpointer()
         # TODO non-trivial transformations later; if modified, do not forget to update ScatteringSystem constructor
@@ -331,6 +331,10 @@ cpdef void scatsystem_set_nthreads(long n):
     qpms_scatsystem_set_nthreads(n)
     return
 
+class ScatteringSystemCachingMode(enum.IntEnum):
+    NEVER = QPMS_SS_CACHE_NEVER
+    AUTO = QPMS_SS_CACHE_AUTO
+    ALWAYS = QPMS_SS_CACHE_ALWAYS
 
 cdef class ScatteringSystem:
     '''
@@ -340,6 +344,16 @@ cdef class ScatteringSystem:
     #cdef list Tmatrices # Here we keep the references to occuring T-matrices
     cdef EpsMuGenerator medium_holder # Here we keep the reference to medium generator
     cdef qpms_scatsys_t *s
+    cdef FinitePointGroup sym
+
+    cdef qpms_iri_t iri_py2c(self, iri, allow_None = True):
+        if iri is None and allow_None:
+            return QPMS_NO_IRREP
+        cdef qpms_iri_t nir = self.nirreps
+        cdef qpms_iri_t ciri = iri
+        if ciri < 0 or ciri > nir:
+            raise ValueError("Invalid irrep index %s (of %d irreps)", str(iri), self.nirreps)
+        return ciri
 
     def check_s(self): # cdef instead?
         if self.s == <qpms_scatsys_t *>NULL:
@@ -347,7 +361,9 @@ cdef class ScatteringSystem:
         #TODO is there a way to disable the constructor outside this module?
 
     @staticmethod # We don't have any "standard" constructor for this right now
-    def create(particles, medium, FinitePointGroup sym, cdouble omega): # TODO tolerances
+    def create(particles, medium, FinitePointGroup sym, cdouble omega,
+            caching_mode = QPMS_SS_CACHE_DEFAULT): # TODO tolerances
+        caching_mode = ScatteringSystemCachingMode(caching_mode)
         # These we are going to construct
         cdef ScatteringSystem self
         cdef _ScatteringSystemAtOmega pyssw
@@ -369,7 +385,8 @@ cdef class ScatteringSystem:
         for p in particles: # find and enumerate unique t-matrix generators
             if p.p.op.typ != QPMS_TMATRIX_OPERATION_NOOP:
                 raise NotImplementedError("currently, only no-op T-matrix operations are allowed in ScatteringSystem constructor")
-            tmg_key = id(p.f)
+            #tmg_key = id(p.f) # This causes a different generator for each particle -> SUPER SLOW
+            tmg_key = (id(p.f.generator), id(p.f.spec))
             if tmg_key not in tmgindices:
                 tmgindices[tmg_key] = tmg_count
                 tmgobjs.append(p.f) # Save the references on BaseSpecs and TMatrixGenerators (via TMatrixFunctions)
@@ -401,12 +418,13 @@ cdef class ScatteringSystem:
                 orig.tm[tmi].op = qpms_tmatrix_operation_noop # TODO adjust when notrivial operations allowed
             for pi in range(p_count):
                 p = particles[pi]
-                tmg_key = id(p.f)
+                tmg_key = (id(p.f.generator), id(p.f.spec))
                 tm_derived_key = (tmg_key, None) # TODO unique representation of p.p.op instead of None
                 orig.p[pi].pos = p.cval().pos
                 orig.p[pi].tmatrix_id = tmindices[tm_derived_key]
             ssw = qpms_scatsys_apply_symmetry(&orig, sym.rawpointer(), omega, &QPMS_TOLERANCE_DEFAULT)
             ss = ssw[0].ss
+            qpms_ss_create_translation_cache(ss, caching_mode)
         finally:
             free(orig.tmg)
             free(orig.tm)
@@ -415,6 +433,7 @@ cdef class ScatteringSystem:
         self.medium_holder = mediumgen
         self.s = ss
         self.tmgobjs = tmgobjs
+        self.sym = sym
         pyssw = _ScatteringSystemAtOmega()
         pyssw.ssw = ssw
         pyssw.ss_pyref = self
@@ -588,6 +607,65 @@ cdef class ScatteringSystem:
                 self.s, qpms_incfield_planewave, <void *>&p, 0)
         return target_np
 
+    property has_translation_cache:
+        def __get__(self):
+            self.check_s()
+            return True if qpms_scatsys_has_translation_cache(self.s) else False
+
+    def find_modes(self, cdouble omega_centre, double omega_rr, double omega_ri, iri = None,
+            size_t contour_points = 20, double rank_tol = 1e-4, size_t rank_min_sel=1,
+            double res_tol = 0):
+        """
+        Attempts to find the eigenvalues and eigenvectors using Beyn's algorithm.
+        """
+
+        cdef beyn_result_t *res = qpms_scatsys_finite_find_eigenmodes(self.s, 
+                self.iri_py2c(iri),
+                omega_centre, omega_rr, omega_ri, contour_points, 
+                rank_tol, rank_min_sel, res_tol)
+        if res == NULL: raise RuntimeError
+
+        cdef size_t neig = res[0].neig
+        cdef size_t vlen = res[0].vlen # should be equal to self.s.fecv_size
+
+        cdef np.ndarray[complex, ndim=1] eigval = np.empty((neig,), dtype=complex)
+        cdef cdouble[::1] eigval_v = eigval
+        cdef np.ndarray[complex, ndim=1] eigval_err = np.empty((neig,), dtype=complex)
+        cdef cdouble[::1] eigval_err_v = eigval_err
+        cdef np.ndarray[double, ndim=1] residuals = np.empty((neig,), dtype=np.double)
+        cdef double[::1] residuals_v = residuals
+        cdef np.ndarray[complex, ndim=2] eigvec = np.empty((neig,vlen),dtype=complex)
+        cdef cdouble[:,::1] eigvec_v = eigvec
+        cdef np.ndarray[double, ndim=1] ranktest_SV = np.empty((vlen), dtype=np.double)
+        cdef double[::1] ranktest_SV_v = ranktest_SV
+
+        cdef size_t i, j
+
+        for i in range(neig):
+            eigval_v[i] = res[0].eigval[i]
+            eigval_err_v[i] = res[0].eigval_err[i]
+            residuals_v[i] = res[0].residuals[i]
+            for j in range(vlen):
+                eigvec_v[i,j] = res[0].eigvec[i*vlen + j]
+        for i in range(vlen):
+            ranktest_SV_v[i] = res[0].ranktest_SV[i]
+
+        zdist = eigval - omega_centre
+        eigval_inside_metric = np.hypot(zdist.real / omega_rr, zdist.imag / omega_ri)
+
+        beyn_result_free(res)
+        retdict = {
+                'eigval':eigval,
+                'eigval_inside_metric':eigval_inside_metric,
+                'eigvec':eigvec,
+                'residuals':residuals,
+                'eigval_err':eigval_err,
+                'ranktest_SV':ranktest_SV,
+                'iri': iri,
+        }
+
+        return retdict
+
 cdef class _ScatteringSystemAtOmega:
     '''
     Wrapper over the C qpms_scatsys_at_omega_t structure
@@ -635,6 +713,21 @@ cdef class _ScatteringSystemAtOmega:
         def __get__(self): return self.ss_pyref.irrep_names
     property nirreps: 
         def __get__(self): return self.ss_pyref.nirreps
+    property has_translation_cache:
+        def __get__(self):
+            self.check()
+            return True if qpms_scatsysw_has_translation_cache(self.ssw) else False
+
+    def add_translation_cache(self):
+        '''
+        Adds translation cache if the parent ScatteringSystem
+        contains the required metadata (this is not done automatically,
+        as the cache is not useful if no translation operators are to
+        be evaluated
+        '''
+        self.check()
+        qpms_ssw_create_translation_cache(self.ssw)
+        return self.has_translation_cache
 
     def modeproblem_matrix_full(self):
         self.check()

qpms/qpms_cdefs.pxd

@@ -107,6 +107,7 @@ cdef extern from "qpms_types.h":
     ctypedef int32_t qpms_ss_pi_t
     ctypedef int qpms_gmi_t
     ctypedef int qpms_iri_t
+    qpms_iri_t QPMS_NO_IRREP
     ctypedef const char * qpms_permutation_t
     struct qpms_tmatrix_t:
         qpms_vswf_set_spec_t *spec
@@ -549,10 +550,17 @@ cdef extern from "scatsystem.h":
         cdouble omega
         qpms_epsmu_t medium
         cdouble wavenumber
+    ctypedef enum qpms_ss_caching_mode_t:
+        QPMS_SS_CACHE_NEVER
+        QPMS_SS_CACHE_ALWAYS
+        QPMS_SS_CACHE_DEFAULT
+        QPMS_SS_CACHE_AUTO
     qpms_scatsys_at_omega_t *qpms_scatsys_apply_symmetry(const qpms_scatsys_t *orig, const qpms_finite_group_t *sym,
             cdouble omega, const qpms_tolerance_spec_t *tol)
     qpms_scatsys_at_omega_t *qpms_scatsys_at_omega(const qpms_scatsys_t *ss, cdouble omega)
     void qpms_scatsys_at_omega_free(qpms_scatsys_at_omega_t *ssw)
+    int qpms_ss_create_translation_cache(qpms_scatsys_t *ss, qpms_ss_caching_mode_t m)
+    int qpms_ssw_create_translation_cache(qpms_scatsys_at_omega_t *ssw)
     cdouble *qpms_scatsys_irrep_pack_matrix(cdouble *target_packed,
             const cdouble *orig_full, const qpms_scatsys_t *ss, qpms_iri_t iri)
     cdouble *qpms_scatsys_irrep_unpack_matrix(cdouble *target_full, 
@@ -598,6 +606,11 @@ cdef extern from "scatsystem.h":
     cdouble *qpms_scatsys_scatter_solve(cdouble *target_f, const cdouble *a_inc, qpms_ss_LU ludata)
     const qpms_vswf_set_spec_t *qpms_ss_bspec_tmi(const qpms_scatsys_t *ss, qpms_ss_tmi_t tmi)
     const qpms_vswf_set_spec_t *qpms_ss_bspec_pi(const qpms_scatsys_t *ss, qpms_ss_pi_t pi)
+    beyn_result_t *qpms_scatsys_finite_find_eigenmodes(const qpms_scatsys_t *ss, qpms_iri_t iri,
+            cdouble omega_centre, double omega_rr, double omega_ri, size_t contour_npoints, 
+            double rank_tol, size_t rank_sel_min, double res_tol)
+    bint qpms_scatsysw_has_translation_cache(const qpms_scatsys_at_omega_t *ssw)
+    bint qpms_scatsys_has_translation_cache(const qpms_scatsys_t *ss)
 
 cdef extern from "ewald.h":
     struct qpms_csf_result:
@@ -674,11 +687,11 @@ cdef extern from "beyn.h":
 
     beyn_result_gsl_t *beyn_solve_gsl(size_t m, size_t l, beyn_function_M_gsl_t M,
             beyn_function_M_inv_Vhat_gsl_t M_inv_Vhat, void *params, const beyn_contour_t *contour,
-            double rank_tol, double res_tol)
+            double rank_tol, size_t rank_min_sel, double res_tol)
 
     beyn_result_t *beyn_solve(size_t m, size_t l, beyn_function_M_t M,
             beyn_function_M_inv_Vhat_t M_inv_Vhat, void *params, const beyn_contour_t *contour,
-            double rank_tol, double res_tol)
+            double rank_tol, size_t rank_min_sel, double res_tol)
 
     beyn_contour_t *beyn_contour_ellipse(cdouble centre, double halfax_re, double halfax_im, size_t npoints)
     beyn_contour_t *beyn_contour_halfellipse(cdouble centre, double halfax_re, double halfax_im, size_t npoints,

qpms/qpms_error.h

@@ -4,14 +4,14 @@
 #include "optim.h"
 
 /// Provisional error message with abort();
-void qpms_pr_error(const char *fmt, ...);
+QPMS_NORETURN void qpms_pr_error(const char *fmt, ...);
 //void qpms_error(const char *fmt, ...);
 
 /// Provisional error message with abort(), indicating source and line number.
 void qpms_pr_error_at_line(const char *filename, unsigned int linenum,
 		const char *fmt, ...);
 
-void qpms_pr_error_at_flf(const char *filename, unsigned int linenum,
+QPMS_NORETURN void qpms_pr_error_at_flf(const char *filename, unsigned int linenum,
 		const char *func,
 	       const char *fmt, ...);
 
@@ -100,6 +100,13 @@ qpms_dbgmsg_flags qpms_dbgmsg_enable(qpms_dbgmsg_flags types);
 		qpms_pr_error_at_flf(__FILE__,__LINE__,__func__,"Unexpected error (%d)", errorcode); \
 }
 
+// Same as previous, but with message.
+#define QPMS_ENSURE_SUCCESS_M(x, msg, ...) { \
+	int errorcode = (x); \
+	if(QPMS_UNLIKELY(errorcode)) \
+		qpms_pr_error_at_flf(__FILE__,__LINE__,__func__,msg, ##__VA_ARGS__); \
+}
+
 
 #define QPMS_ENSURE(x, msg, ...) {if(QPMS_UNLIKELY(!(x))) qpms_pr_error_at_flf(__FILE__,__LINE__,__func__,msg, ##__VA_ARGS__); }
 
@@ -109,6 +116,16 @@ qpms_dbgmsg_flags qpms_dbgmsg_enable(qpms_dbgmsg_flags types);
 			"Unexpected error. This is most certainly a bug.");\
 }
 
+#ifdef QPMS_EVALUATE_PARANOID_ASSERTS
+  #define QPMS_PARANOID_ASSERT(x) {\
+	if(QPMS_UNLIKELY(!(x)))\
+       		qpms_pr_error_at_flf(__FILE__,__LINE__,__func__,\
+			"Unexpected error. This is most certainly a bug.");\
+}
+#else
+  #define QPMS_PARANOID_ASSERT(x) {;}
+#endif
+
 #define QPMS_NOT_IMPLEMENTED(msg, ...) qpms_pr_error_at_flf(__FILE__,__LINE__,__func__, \
 		"Not implemented:" msg, ##__VA_ARGS__)
 

qpms/qpms_types.h

@@ -309,6 +309,8 @@ typedef int qpms_gmi_t;
 
 /// Irreducible representation index. See also groups.h.
 typedef int qpms_iri_t;
+/// Constant labeling that no irrep decomposition is done (full system solved instead).
+#define QPMS_NO_IRREP ((qpms_iri_t) -1)
 
 /// Permutation representation of a group element.
 /** For now, it's just a string of the form "(0,1)(3,4,5)"

qpms/scatsys_private.h

@@ -0,0 +1,41 @@
+#ifndef QPMS_SCATSYS_PRIVATE_H
+#define QPMS_SCATSYS_PRIVATE_H
+/* 
+ * This file includes some definitions shared between scatsystem.c
+ * and scatsys_translation_booster.c that are not needed anywhere 
+ * else.
+ */
+
+#include "scatsystem.h"
+
+#include <pthread.h>
+
+complex double *qpms_scatsysw_build_modeproblem_matrix_full_boosted(
+		complex double *target, const qpms_scatsys_at_omega_t *ssw);
+complex double *qpms_scatsysw_build_modeproblem_matrix_irrep_packed_boosted(
+		complex double *target_packed, const qpms_scatsys_at_omega_t *ssw, qpms_iri_t iri);
+/// "private" destructor, called by qpms_scatsys_free()
+void qpms_scatsys_translation_booster_free(struct qpms_scatsys_translation_booster *);
+/// "private" constructor, use qpms_ss_create_translation_cache() instead.
+struct qpms_scatsys_translation_booster *qpms_scatsys_translation_booster_create(
+                const qpms_scatsys_t *ss);
+
+
+struct qpms_scatsysw_translation_booster *
+qpms_scatsysw_translation_booster_create(const qpms_scatsys_at_omega_t *ssw);
+
+/// "private" destructor, called by qpms_scatsys_at_omega_free()
+void qpms_scatsysw_translation_booster_free(struct qpms_scatsysw_translation_booster *);
+
+
+struct qpms_scatsysw_build_modeproblem_matrix_irrep_packed_parallelR_thread_arg{
+  const qpms_scatsys_at_omega_t *ssw;
+  qpms_ss_pi_t *opistartR_ptr;
+  pthread_mutex_t *opistartR_mutex;
+  qpms_iri_t iri;
+  complex double *target_packed;
+};
+
+void *qpms_scatsysw_build_modeproblem_matrix_irrep_packed_parallelR_thread_boosted(void *arg);
+
+#endif //QPMS_SCATSYS_PRIVATE_H

qpms/scatsys_translation_booster.c

@@ -0,0 +1,562 @@
+// Functionality to speedup translation matrix computations in large finite arrays
+// by caching Bessel function values etc.
+#include <cblas.h>
+#include "scatsys_private.h"
+#include "translations_inlines.h"
+#include <assert.h>
+#include <stdlib.h>
+#include <math.h>
+#include <string.h>
+#include "vectors.h"
+#include "qpms_error.h"
+#include "qpms_specfunc.h"
+#include "groups.h"
+
+#define SQ(x) ((x)*(x))
+#define MAX(x, y) (((x) > (y)) ? (x) : (y))
+
+#ifdef QPMS_SCATSYSTEM_USE_OWN_BLAS
+#include "qpmsblas.h"
+#define SERIAL_ZGEMM qpms_zgemm
+#else
+#define SERIAL_ZGEMM cblas_zgemm
+#endif
+
+typedef size_t ppid_t;
+typedef size_t uoppid_t;
+
+
+// Unordered exclusive pair ID count. 
+static inline uoppid_t uopairarr_len(qpms_ss_pi_t pn_total) {
+  return pn_total * (pn_total - 1) / 2;
+}
+
+// Unordered exclusive pair ID.
+static inline uoppid_t uopairid(qpms_ss_pi_t pn_total, qpms_ss_pi_t p1, qpms_ss_pi_t p2) {
+  qpms_ss_pi_t hi, lo;
+  QPMS_ASSERT(p1 != p2);
+  if (p1 < p2) {
+    lo = p1;
+    hi = p2;
+  } else {
+    lo = p2;
+    hi = p1;
+  }
+  QPMS_ASSERT(lo >= 0);
+  QPMS_ASSERT(hi < pn_total);
+  return lo + hi * (hi - 1) / 2;
+}
+
+// Ordered pair ID.
+static inline ppid_t pairid(qpms_ss_pi_t pn_total, qpms_ss_pi_t p1, qpms_ss_pi_t p2) {
+  return pn_total * p1 + p2;
+}
+
+// Ordered pair ID count.
+static inline ppid_t pairarr_len(qpms_ss_pi_t pn_total) {
+  return SQ(pn_total);
+}
+
+typedef struct qpms_scatsys_translation_booster {
+  double *r; // Unique distances array, indices are ppid_t
+  qpms_l_t *lMax_r; // lMaxes associated with the r's (use same indices as with r)
+  size_t r_count; // Number of different interparticle distances (length of r[])
+  size_t *r_map; // maps pairs to the corresponding distances (index of uoppid_t type)
+  // Offsets of the Bessel function values: bessel_offsets_r[i] has the cumulative sums
+  // of 2*lMax_r[j]+2, j < i. bessel_offsets_r[r_count] is the total length of the 
+  // Bessel function "cache"
+  size_t *bessel_offsets_r; 
+
+  double *theta;
+  qpms_l_t *lMax_theta;
+  size_t theta_count;
+  size_t *theta_map;
+  size_t *legendre_offsets_theta;
+  double *legendre_base;
+  
+  double *phi;
+  qpms_l_t *lMax_phi;
+  size_t phi_count;
+  size_t *phi_map;
+} booster_t;
+
+/// Sorts an array and throws away duplicit elements.
+/**
+ * The unique elements (according to the compare function) 
+ * are aligned to the left of the original array.
+ *
+ * \returns Number of kept unique array members
+ */
+static size_t sort_and_eliminate(void *base, size_t nmemb, size_t size,
+    int (*compar)(const void *, const void *)) {
+  if (nmemb == 0) return 0; // corner case
+  qsort(base, nmemb, size, compar);
+  size_t left = 0;
+  for (size_t src = 1; src < nmemb; ++src) {
+    assert(left <= src);
+    if (compar((const char *)base + left*size, (const char *)base + src*size)) {
+      left += 1;
+      if (left < src) // Avoid copying to itself (when it's not needed and memcpy behaviour undef'd
+        memcpy((char *)base + left*size, (char *)base + src*size, size);
+    }
+  }
+  return left + 1;
+}
+
+static int cmp_double(const void *aa, const void *bb) {
+  const double a = *(double*)aa;
+  const double b = *(double*)bb;
+  if (a < b) return -1;
+  if (a == b) return 0;
+  if (a > b) return 1;
+  QPMS_WTF; // NaN or similar
+} 
+
+booster_t *qpms_scatsys_translation_booster_create(
+    const qpms_scatsys_t *ss) {
+  const qpms_ss_pi_t np = ss->p_count;
+  booster_t *b;
+  QPMS_CRASHING_MALLOC(b, sizeof(*b));
+
+  QPMS_CRASHING_MALLOC(b->r, sizeof(double) * uopairarr_len(np));
+  QPMS_CRASHING_MALLOC(b->theta, sizeof(double) * pairarr_len(np)); // TODO only one theta per pair
+  QPMS_CRASHING_MALLOC(b->phi, sizeof(double) * pairarr_len(np)); // TODO only one theta per pair
+  for(qpms_ss_pi_t di = 0; di < np; ++di)
+    for(qpms_ss_pi_t si = 0; si < np; ++si) {
+      const ppid_t opid = pairid(np, di, si);
+      if (si != di) {
+        const sph_t dlj = cart2sph(cart3_substract(ss->p[di].pos, ss->p[si].pos));
+        b->r[uopairid(np, di, si)] = dlj.r;
+        b->theta[opid] = dlj.theta;
+        b->phi[opid] = dlj.phi;
+      }
+      else {  // NOT USED IN ACTUAL CALCULATIONS, but must be valid doubles for sorting (infinities might be ok as well)
+        b->theta[opid] = M_PI_2;
+        b->phi[opid] = 0;
+      }
+    }
+
+  b->r_count = sort_and_eliminate(b->r, uopairarr_len(np), sizeof(*b->r), cmp_double);
+  QPMS_CRASHING_REALLOC(b->r, b->r_count * sizeof(*b->r));
+  b->theta_count = sort_and_eliminate(b->theta, pairarr_len(np), sizeof(*b->theta), cmp_double);
+  QPMS_CRASHING_REALLOC(b->theta, b->theta_count * sizeof(*b->theta));
+  b->phi_count = sort_and_eliminate(b->phi, pairarr_len(np), sizeof(*b->phi), cmp_double);
+  QPMS_CRASHING_REALLOC(b->phi, b->phi_count * sizeof(*b->phi));
+
+  QPMS_CRASHING_CALLOC(b->lMax_r, b->r_count, sizeof(*b->lMax_r));
+  QPMS_CRASHING_MALLOC(b->r_map, uopairarr_len(np) * sizeof(*b->r_map));
+  
+  QPMS_CRASHING_CALLOC(b->lMax_theta, b->theta_count, sizeof(*b->lMax_theta));
+  QPMS_CRASHING_MALLOC(b->theta_map, pairarr_len(np) * sizeof(*b->theta_map));
+  
+  QPMS_CRASHING_CALLOC(b->lMax_phi, b->phi_count, sizeof(*b->lMax_phi));
+  QPMS_CRASHING_MALLOC(b->phi_map, pairarr_len(np) * sizeof(*b->phi_map));
+  
+  for(qpms_ss_pi_t di = 0; di < np; ++di)
+    for(qpms_ss_pi_t si = 0; si < np; ++si) {
+      if (si != di) {
+        const ppid_t opid = pairid(np, di, si);
+        const uoppid_t uopid = uopairid(np, di, si);
+        const sph_t dlj = cart2sph(cart3_substract(ss->p[di].pos, ss->p[si].pos));
+        
+        double *hit = bsearch(&dlj.r, b->r, b->r_count, sizeof(*b->r), cmp_double);
+        QPMS_ASSERT(hit != NULL);
+        QPMS_ASSERT(hit >= b->r);
+        const size_t ri = b->r_map[uopid] = hit - b->r;
+        b->lMax_r[ri] = MAX(b->lMax_r[ri], 
+            MAX(qpms_ss_bspec_pi(ss, di)->lMax, qpms_ss_bspec_pi(ss, si)->lMax));
+
+        hit = bsearch(&dlj.theta, b->theta, b->theta_count, sizeof(*b->theta), cmp_double);
+        QPMS_ASSERT(hit != NULL);
+        QPMS_ASSERT(hit >= b->theta);
+        const size_t thi = b->theta_map[opid] = hit - b->theta;
+        b->lMax_theta[thi] = MAX(b->lMax_theta[thi], 
+            MAX(qpms_ss_bspec_pi(ss, di)->lMax, qpms_ss_bspec_pi(ss, si)->lMax));
+
+        hit = bsearch(&dlj.phi, b->phi, b->phi_count, sizeof(*b->phi), cmp_double);
+        QPMS_ASSERT(hit != NULL);
+        QPMS_ASSERT(hit >= b->phi);
+        const size_t phj = b->phi_map[opid] = hit - b->phi;
+        b->lMax_phi[phj] = MAX(b->lMax_phi[phj], 
+            MAX(qpms_ss_bspec_pi(ss, di)->lMax, qpms_ss_bspec_pi(ss, si)->lMax));
+
+        // TODO ri, thi, phj (+bspec?) -tuples here
+      }
+    }
+
+  { // Bessel offsets
+    QPMS_CRASHING_MALLOC(b->bessel_offsets_r, (b->r_count + 1) * sizeof(*b->bessel_offsets_r));
+    size_t bessel_offset = 0;
+    for(size_t ri = 0; ri < b->r_count; ++ri) {
+      b->bessel_offsets_r[ri] = bessel_offset;
+      bessel_offset += 2 * b->lMax_r[ri] + 2;
+    }
+    b->bessel_offsets_r[b->r_count] = bessel_offset;
+  }
+  
+  { // Legendres
+    QPMS_CRASHING_MALLOC(b->legendre_offsets_theta, (b->theta_count + 1) * sizeof(*b->legendre_offsets_theta));
+    size_t legendre_offset = 0;
+    for(size_t thi = 0; thi < b->theta_count; ++thi) {
+      b->legendre_offsets_theta[thi] = legendre_offset;
+      legendre_offset += gsl_sf_legendre_array_n(2*b->lMax_theta[thi] + 1);
+    }
+    b->legendre_offsets_theta[b->theta_count] = legendre_offset;
+    QPMS_CRASHING_MALLOC(b->legendre_base, legendre_offset * sizeof(*b->legendre_base));
+    for(size_t thi = 0; thi < b->theta_count; ++thi) {
+      const double costheta = cos(b->theta[thi]);
+      double *legendre_buf = b->legendre_base + b->legendre_offsets_theta[thi];
+      QPMS_ENSURE_SUCCESS(gsl_sf_legendre_array_e(GSL_SF_LEGENDRE_NONE,
+            2*b->lMax_theta[thi]+1, costheta, -1, legendre_buf));
+    }
+  }
+
+  return b;
+}
+
+void qpms_scatsys_translation_booster_free(booster_t *b) {
+  if (b) {
+    free(b->bessel_offsets_r);
+    free(b->lMax_r);
+    free(b->r);
+    free(b->r_map);
+    free(b->legendre_base);
+    free(b->legendre_offsets_theta);
+    free(b->lMax_theta);
+    free(b->theta);
+    free(b->theta_map);
+    free(b->lMax_phi);
+    free(b->phi);
+    free(b->phi_map);
+    free(b);
+  }
+}
+
+int qpms_ss_create_translation_cache(qpms_scatsys_t *ss, qpms_ss_caching_mode_t m) {
+  QPMS_ASSERT(ss);
+  if (ss->tbooster) {
+    QPMS_WARN("Translation cache already created?");
+    return 0;
+  }
+  switch(m) {
+    case QPMS_SS_CACHE_NEVER:
+      return 0;
+    case QPMS_SS_CACHE_AUTO:
+      QPMS_WARN("Translation operator cache heuristics not implemented, creating the cache");
+    case QPMS_SS_CACHE_ALWAYS:
+      ss->tbooster = qpms_scatsys_translation_booster_create(ss);
+      if (ss->tbooster) return 0;
+      else {
+        QPMS_WARN("Failed to create tranlation operator cache");
+        return -1;
+      }
+    default:
+      QPMS_WTF;
+  }
+  QPMS_WTF;
+}
+
+static qpms_errno_t qpms_scatsys_translation_booster_eval_bessels(
+    const booster_t *b, complex double *target, complex double k // includes ref. ind. effect
+    ) {
+  for(size_t ri = 0; ri < b->r_count; ++ri) {
+    QPMS_ENSURE_SUCCESS(qpms_sph_bessel_fill(QPMS_HANKEL_PLUS, // Is there a case for different J?
+          2*b->lMax_r[ri]+1, k * b->r[ri], 
+          target + b->bessel_offsets_r[ri]));
+  }
+  return QPMS_SUCCESS;
+}
+
+typedef struct qpms_scatsysw_translation_booster {
+  // _Bool owned_by_ssw; // if False, this is not deallocated by parent ssw
+  const booster_t *b;
+  complex double *bessels;
+} boosterw_t;
+
+boosterw_t *qpms_scatsysw_translation_booster_create(
+    const qpms_scatsys_at_omega_t *ssw) {
+  QPMS_PARANOID_ASSERT(ssw->ss);
+  const booster_t *const b = ssw->ss->tbooster;
+  QPMS_ASSERT(b);
+  boosterw_t *bw;
+  QPMS_CRASHING_MALLOC(bw, sizeof(*bw));
+
+  // Evaluate bessel functions
+  QPMS_CRASHING_MALLOC(bw->bessels, b->bessel_offsets_r[b->r_count] * sizeof(*bw->bessels));
+  for(size_t ri = 0; ri < b->r_count; ++ri) {
+    QPMS_ENSURE_SUCCESS(qpms_sph_bessel_fill(QPMS_HANKEL_PLUS, // is there a case for other J?
+          b->bessel_offsets_r[ri+1]-b->bessel_offsets_r[ri]-1,
+          b->r[ri] * ssw->wavenumber,
+          bw->bessels + b->bessel_offsets_r[ri]));
+  }
+
+  bw->b = b;
+  return bw;
+}
+
+void qpms_scatsysw_translation_booster_free(boosterw_t *bw) {
+  if (bw) {
+    free (bw->bessels);
+  }
+  free (bw);
+}
+
+complex double *qpms_scatsysw_build_modeproblem_matrix_full_boosted(
+    /// Target memory with capacity for ss->fecv_size**2 elements. If NULL, new will be allocated.
+    complex double *target,
+    const qpms_scatsys_at_omega_t *ssw) 
+{
+  QPMS_ASSERT(ssw->translation_cache && ssw->ss->tbooster);
+  const qpms_scatsys_t *const ss = ssw->ss;
+  const booster_t *const b = ss->tbooster;
+  const boosterw_t *const bw = ssw->translation_cache;
+  const qpms_trans_calculator *const c = ss->c;
+
+  const complex double k = ssw->wavenumber;
+  const size_t full_len = ss->fecv_size;
+  if(!target)
+    QPMS_CRASHING_MALLOC(target, SQ(full_len) * sizeof(complex double));
+  complex double *tmp;
+  QPMS_CRASHING_MALLOC(tmp, SQ(ss->max_bspecn) * sizeof(complex double));
+  // Workspaces for the translation operator A and B matrices
+  complex double *A, *B;
+  QPMS_CRASHING_MALLOC(A, SQ(c->nelem) * sizeof(*A));
+  QPMS_CRASHING_MALLOC(B, SQ(c->nelem) * sizeof(*B));
+  memset(target, 0, SQ(full_len) * sizeof(complex double)); //unnecessary?
+  double legendre_buf[gsl_sf_legendre_array_n(2*c->lMax + 1)]; //VLA, workspace for legendre arrays
+  const complex double zero = 0, minusone = -1;
+  { // Non-diagonal part; M[piR, piC] = -T[piR] S(piR<-piC)
+    size_t fullvec_offsetR = 0;
+    for(qpms_ss_pi_t piR = 0; piR < ss->p_count; ++piR) {
+      const qpms_vswf_set_spec_t *bspecR = ssw->tm[ss->p[piR].tmatrix_id]->spec;
+      const cart3_t posR = ss->p[piR].pos;
+      size_t fullvec_offsetC = 0;
+      // dest particle T-matrix
+      const complex double *tmmR = ssw->tm[ss->p[piR].tmatrix_id]->m;
+      for(qpms_ss_pi_t piC = 0; piC < ss->p_count; ++piC) {
+        const qpms_vswf_set_spec_t *bspecC = ssw->tm[ss->p[piC].tmatrix_id]->spec;
+        if(piC != piR) { // The diagonal will be dealt with later.
+          const cart3_t posC = ss->p[piC].pos;
+#if 0
+          QPMS_ENSURE_SUCCESS(qpms_trans_calculator_get_trans_array_lc3p(ss->c,
+                tmp, // tmp is S(piR<-piC)
+                bspecR, bspecC->n, bspecC, 1,
+                k, posR, posC, QPMS_HANKEL_PLUS));
+#else
+          { // this replaces qpms_trans_calculator_get_trans_array():
+            // R is dest, C is src
+            const sph_t dlj = cart2sph(cart3_substract(posR, posC));
+            const uoppid_t pid = uopairid(ss->p_count, piR, piC);
+            const size_t ri = b->r_map[pid];
+            QPMS_PARANOID_ASSERT(dlj.r == b->r[ri]);
+            const qpms_l_t pair_lMax = b->lMax_r[ri];
+            const qpms_y_t pair_nelem = qpms_lMax2nelem(pair_lMax);
+            QPMS_PARANOID_ASSERT(c->normalisation == bspecC->norm && c->normalisation == bspecR->norm);
+            QPMS_PARANOID_ASSERT(c->lMax >= bspecC->lMax && c->lMax >= bspecR->lMax);
+            QPMS_PARANOID_ASSERT(bspecC->lMax_L < 0 && bspecR->lMax_L < 0);
+            { // this replaces qpms_trans_calculator_get_AB_arrays() and ..._buf()
+              const double costheta = cos(dlj.theta);
+              QPMS_ENSURE_SUCCESS(gsl_sf_legendre_array_e(GSL_SF_LEGENDRE_NONE,
+                    2*pair_lMax+1, costheta, -1, legendre_buf));
+              const double * const legendres = legendre_buf;
+              const complex double * const bessels = bw->bessels + b->bessel_offsets_r[ri];
+              qpms_trans_calculator_get_AB_arrays_precalcbuf(c, pair_lMax, A, B,
+                  /*deststride*/ pair_nelem, /*srcstride*/ 1, dlj.phi, bessels, legendres);
+              qpms_trans_array_from_AB(tmp,// tmp is S(piR<-piC) 
+                  bspecR, bspecC->n, bspecC, 1, A, B, pair_lMax);
+            }
+          }
+#endif
+          cblas_zgemm(CblasRowMajor, CblasNoTrans, CblasNoTrans,
+              bspecR->n /*m*/, bspecC->n /*n*/, bspecR->n /*k*/,
+              &minusone/*alpha*/, tmmR/*a*/, bspecR->n/*lda*/,
+              tmp/*b*/, bspecC->n/*ldb*/, &zero/*beta*/,
+              target + fullvec_offsetR*full_len + fullvec_offsetC /*c*/,
+              full_len /*ldc*/);
+        }
+        fullvec_offsetC += bspecC->n;
+      }
+      fullvec_offsetR += bspecR->n;
+    }
+  }
+  // diagonal part M[pi,pi] = +1
+  for (size_t i = 0; i < full_len; ++i) target[full_len * i + i] = +1;
+
+  free(tmp);
+  free(A);
+  free(B);
+  return target;
+}
+
+void *qpms_scatsysw_build_modeproblem_matrix_irrep_packed_parallelR_thread_boosted(void *arg)
+{
+  const struct qpms_scatsysw_build_modeproblem_matrix_irrep_packed_parallelR_thread_arg 
+    *a = arg;
+  const qpms_scatsys_at_omega_t *ssw = a->ssw;
+  QPMS_ASSERT(ssw->translation_cache && ssw->ss->tbooster);
+  const qpms_scatsys_t * const ss = ssw->ss;
+  const qpms_trans_calculator *const c = ss->c;
+  const booster_t *const b = ss->tbooster;
+  const boosterw_t *const bw = ssw->translation_cache;
+  const complex double k = ssw->wavenumber;
+  const qpms_iri_t iri = a->iri;
+  const size_t packedlen = ss->saecv_sizes[iri];
+
+  // some of the following workspaces are probably redundant; TODO optimize later.
+
+  // workspaces for the uncompressed particle<-particle tranlation matrix block
+  // and the result of multiplying with a T-matrix (times -1)
+  complex double *Sblock, *TSblock;
+  QPMS_CRASHING_MALLOC(Sblock, sizeof(complex double)*SQ(ss->max_bspecn));
+  QPMS_CRASHING_MALLOC(TSblock, sizeof(complex double)*SQ(ss->max_bspecn));
+
+  // Workspace for the intermediate particle-orbit matrix result
+  complex double *tmp;
+  QPMS_CRASHING_MALLOC(tmp, sizeof(complex double) * SQ(ss->max_bspecn) * ss->sym->order);
+  // Workspace for A, B arrays
+  complex double *A, *B;
+  QPMS_CRASHING_MALLOC(A, SQ(c->nelem) * sizeof(*A));
+  QPMS_CRASHING_MALLOC(B, SQ(c->nelem) * sizeof(*B));
+  double legendre_buf[gsl_sf_legendre_array_n(2*c->lMax + 1)]; //VLA, workspace for legendre arrays
+
+  const complex double one = 1, zero = 0, minusone = -1;
+
+  while(1) {
+    // In the beginning, pick a target (row) orbit for this thread
+    QPMS_ENSURE_SUCCESS(pthread_mutex_lock(a->opistartR_mutex));
+    if(*(a->opistartR_ptr) >= ss->p_count) {// Everything is already done, end
+      QPMS_ENSURE_SUCCESS(pthread_mutex_unlock(a->opistartR_mutex));
+      break; 
+    }
+    const qpms_ss_pi_t opistartR = *(a->opistartR_ptr);
+    // Now increment it for another thread:
+    *(a->opistartR_ptr) += ss->orbit_types[ss->p_orbitinfo[ss->p_by_orbit[opistartR]].t].size;
+    QPMS_ENSURE_SUCCESS(pthread_mutex_unlock(a->opistartR_mutex));
+    
+    // Orbit picked (defined by opistartR), do the work.
+    const qpms_ss_pi_t orbitstartpiR = ss->p_by_orbit[opistartR];
+    const qpms_ss_oti_t otiR = ss->p_orbitinfo[orbitstartpiR].t;
+    const qpms_ss_osn_t osnR = ss->p_orbitinfo[orbitstartpiR].osn;
+    const qpms_ss_orbit_type_t *const otR = ss->orbit_types + otiR;
+    const qpms_ss_orbit_pi_t orbit_p_countR = otR->size;
+    const size_t orbit_packedsizeR = otR->irbase_sizes[iri];
+
+    if(orbit_packedsizeR) { // avoid zgemm crash on empty irrep
+      const size_t particle_fullsizeR = otR->bspecn; // == bspecR->n
+      const qpms_vswf_set_spec_t *bspecR = ssw->tm[ss->p[orbitstartpiR].tmatrix_id]->spec;
+      // This is the orbit-level matrix projecting the whole orbit onto the irrep.
+      const complex double *omR = otR->irbases + otR->irbase_offsets[iri];
+      // Orbit coeff vector's full size:
+      const size_t orbit_fullsizeR = otR->size * otR->bspecn;
+      // This is where the orbit starts in the "packed" vector:
+      const size_t packed_orbit_offsetR =
+        ss->saecv_ot_offsets[iri*ss->orbit_type_count + otiR] 
+        + osnR * otR->irbase_sizes[iri];
+      for(qpms_ss_orbit_pi_t opiR = 0; opiR < orbit_p_countR; ++opiR) {
+        qpms_ss_pi_t piR = ss->p_by_orbit[opistartR + opiR];
+        assert(opiR == ss->p_orbitinfo[piR].p);
+        assert(otiR == ss->p_orbitinfo[piR].t);
+        assert(ss->p_orbitinfo[piR].osn == osnR);
+        const cart3_t posR = ss->p[piR].pos;
+        // dest particle T-matrix
+        const complex double *tmmR = ssw->tm[ss->p[piR].tmatrix_id]->m;
+        for(qpms_ss_pi_t piC = 0; piC < ss->p_count; ++piC) { //Column loop
+          const qpms_ss_oti_t otiC = ss->p_orbitinfo[piC].t;
+          const qpms_ss_orbit_type_t *const otC = ss->orbit_types + otiC;
+          const qpms_ss_osn_t osnC = ss->p_orbitinfo[piC].osn;
+          const qpms_ss_orbit_pi_t opiC = ss->p_orbitinfo[piC].p;
+          // This is where the particle's orbit starts in the "packed" vector:
+          const size_t packed_orbit_offsetC = 
+            ss->saecv_ot_offsets[iri*ss->orbit_type_count + otiC]
+            + osnC * otC->irbase_sizes[iri];
+          const qpms_vswf_set_spec_t *bspecC = ssw->tm[ss->p[piC].tmatrix_id]->spec;
+          // Orbit coeff vector's full size:
+          const size_t orbit_fullsizeC = otC->size * otC->bspecn;
+          const size_t particle_fullsizeC = otC->bspecn; // == bspecC->n
+          const size_t orbit_packedsizeC = otC->irbase_sizes[iri];
+          // This is the orbit-level matrix projecting the whole orbit onto the irrep.
+          const complex double *omC = otC->irbases + otC->irbase_offsets[iri];
+
+          if(orbit_packedsizeC) { // avoid zgemm crash on empty irrep
+            if(piC != piR) { // non-diagonal, calculate TS
+              const cart3_t posC = ss->p[piC].pos;
+#if 0
+              QPMS_ENSURE_SUCCESS(qpms_trans_calculator_get_trans_array_lc3p(ss->c,
+                    Sblock, // Sblock is S(piR->piC)
+                    bspecR, bspecC->n, bspecC, 1,
+                    k, posR, posC, QPMS_HANKEL_PLUS));
+#else
+              { // this block replaces qpms_trans_calculator_get_trans_array():
+                // R is dest, C is src
+                const sph_t dlj = cart2sph(cart3_substract(posR, posC));
+                const uoppid_t uopid = uopairid(ss->p_count, piR, piC);
+                const ppid_t opid = pairid(ss->p_count, piR, piC);
+                const size_t ri  = b->r_map[uopid];
+                const size_t thi = b->theta_map[opid];
+                QPMS_PARANOID_ASSERT(dlj.r == b->r[ri]);
+                QPMS_PARANOID_ASSERT(dlj.theta == b->theta[thi]);
+                const qpms_l_t pair_lMax = b->lMax_r[ri];
+                const qpms_y_t pair_nelem = qpms_lMax2nelem(pair_lMax);
+                QPMS_PARANOID_ASSERT(c->normalisation == bspecC->norm && c->normalisation == bspecR->norm);
+                QPMS_PARANOID_ASSERT(c->lMax >= bspecC->lMax && c->lMax >= bspecR->lMax);
+                QPMS_PARANOID_ASSERT(bspecC->lMax_L < 0 && bspecR->lMax_L < 0);
+                { // this replaces qpms_trans_calculator_get_AB_arrays() and _buf()
+#if 0
+                  const double costheta = cos(dlj.theta);
+                  QPMS_ENSURE_SUCCESS(gsl_sf_legendre_array_e(GSL_SF_LEGENDRE_NONE,
+                        2*pair_lMax+1, costheta, -1, legendre_buf));
+                  const double * const legendres = legendre_buf;
+#else
+                  const double * const legendres = b->legendre_base + b->legendre_offsets_theta[thi];
+#endif
+                  const complex double * const bessels = bw->bessels + b->bessel_offsets_r[ri];
+                  qpms_trans_calculator_get_AB_arrays_precalcbuf(c, pair_lMax, A, B,
+                      /*deststride*/ pair_nelem, /*srcstride*/ 1, dlj.phi, bessels, legendres);
+                }
+                qpms_trans_array_from_AB(Sblock, // Sblock is S(piR->piC)
+                    bspecR, bspecC->n, bspecC, 1, A, B, pair_lMax);
+              }
+
+#endif
+
+              SERIAL_ZGEMM(CblasRowMajor, CblasNoTrans, CblasNoTrans,
+                  bspecR->n /*m*/, bspecC->n /*n*/, bspecR->n /*k*/,
+                  &minusone/*alpha*/, tmmR/*a*/, bspecR->n/*lda*/,
+                  Sblock/*b*/, bspecC->n/*ldb*/, &zero/*beta*/,
+                  TSblock /*c*/, bspecC->n /*ldc*/);
+            } else { // diagonal, fill with diagonal +1
+              for (size_t row = 0; row < bspecR->n; ++row)
+                for (size_t col = 0; col < bspecC->n; ++col)
+                  TSblock[row * bspecC->n + col] = (row == col)? +1 : 0;
+            }
+
+            // tmp[oiR|piR,piC] = ∑_K M[piR,K] U*[K,piC]
+            SERIAL_ZGEMM(CblasRowMajor, CblasNoTrans, CblasConjTrans,
+                particle_fullsizeR /*M*/, orbit_packedsizeC /*N*/, particle_fullsizeC /*K*/,
+                &one /*alpha*/, TSblock/*A*/, particle_fullsizeC/*ldA*/, 
+                omC + opiC*particle_fullsizeC /*B*/,
+                orbit_fullsizeC/*ldB*/, &zero /*beta*/,
+                tmp /*C*/, orbit_packedsizeC /*LDC*/);
+
+            // target[oiR|piR,oiC|piC] += U[...] tmp[...]
+            SERIAL_ZGEMM(CblasRowMajor, CblasNoTrans, CblasNoTrans,
+                orbit_packedsizeR /*M*/, orbit_packedsizeC /*N*/, particle_fullsizeR /*K*/,
+                &one /*alpha*/, omR + opiR*particle_fullsizeR/*A*/, orbit_fullsizeR/*ldA*/,
+                tmp /*B*/, orbit_packedsizeC /*ldB*/, &one /*beta*/,
+                a->target_packed + packedlen*packed_orbit_offsetR + packed_orbit_offsetC /*C*/,
+                packedlen /*ldC*/);
+          }
+        }
+      }
+    }
+  }
+  free(A);
+  free(B);
+  free(tmp);
+  free(Sblock);
+  free(TSblock);
+  return NULL;
+}
+
+
+

qpms/scatsystem.c

@@ -6,7 +6,7 @@
 #include <lapacke.h>
 #include <cblas.h>
 #include <lapacke.h>
-#include "scatsystem.h"
+#include "scatsys_private.h"
 #include "indexing.h"
 #include "vswf.h"
 #include "groups.h"
@@ -22,6 +22,7 @@
 #include <pthread.h>
 #include "kahansum.h"
 #include "tolerances.h"
+#include "beyn.h"
 
 #ifdef QPMS_SCATSYSTEM_USE_OWN_BLAS
 #include "qpmsblas.h"
@@ -133,8 +134,7 @@ static void add_orbit_type(qpms_scatsys_t *ss, const qpms_ss_orbit_type_t *ot_cu
     bs_cumsum += lastbs;
     ot_new->irbase_cumsizes[iri] = bs_cumsum;
   }
-  if(bs_cumsum != ot_new->size * bspecn)
-    qpms_pr_error_at_flf(__FILE__, __LINE__, __func__,
+  QPMS_ENSURE(bs_cumsum == ot_new->size * bspecn,
         "The cumulative size of the symmetry-adapted bases is wrong; "
         "expected %d = %d * %d, got %d.",
         ot_new->size * bspecn, ot_new->size, bspecn, bs_cumsum);
@@ -142,7 +142,6 @@ static void add_orbit_type(qpms_scatsys_t *ss, const qpms_ss_orbit_type_t *ot_cu
   ss->orbit_type_count++;
 }
 
-
 // Almost 200 lines. This whole thing deserves a rewrite!
 qpms_scatsys_at_omega_t *qpms_scatsys_apply_symmetry(const qpms_scatsys_t *orig,
     const qpms_finite_group_t *sym, complex double omega, 
@@ -181,6 +180,7 @@ qpms_scatsys_at_omega_t *qpms_scatsys_apply_symmetry(const qpms_scatsys_t *orig,
   ss->lenscale = lenscale;
   ss->sym = sym;
   ss->medium = orig->medium;
+  ss->tbooster = NULL;
 
   // Copy the qpms_tmatrix_fuction_t from orig
   ss->tmg_count = orig->tmg_count;
@@ -209,6 +209,7 @@ qpms_scatsys_at_omega_t *qpms_scatsys_apply_symmetry(const qpms_scatsys_t *orig,
   QPMS_CRASHING_MALLOC(ssw, sizeof(*ssw)); // returned
   ssw->ss = ss;
   ssw->omega = omega;
+  ssw->translation_cache = NULL;
   ssw->medium = qpms_epsmu_generator_eval(ss->medium, omega);
   ssw->wavenumber = qpms_wavenumber(omega, ssw->medium);
   // we will be using ss->tm_capacity also for ssw->tm
@@ -275,15 +276,17 @@ qpms_scatsys_at_omega_t *qpms_scatsys_apply_symmetry(const qpms_scatsys_t *orig,
       if (tmj < ss->tm_count) { // HIT, transformed T-matrix already exists
         //TODO some "rounding error cleanup" symmetrisation could be performed here?
         qpms_tmatrix_free(transformed);
+        free(m);
       } else { // MISS, save the matrix (also the "abstract" one)
         ssw->tm[ss->tm_count] = transformed;
 	ss->tm[ss->tm_count].tmgi = ss->tm[tmi].tmgi;
-        qpms_tmatrix_operation_compose_chain_init(&(ss->tm[ss->tm_count].op), 2, 1);
+        qpms_tmatrix_operation_compose_chain_init(&(ss->tm[ss->tm_count].op), 2, 1); // FIXME MEMLEAK
         struct qpms_tmatrix_operation_compose_chain * const o = &(ss->tm[ss->tm_count].op.op.compose_chain);
         o->ops[0] = & ss->tm[tmi].op; // Let's just borrow this
         o->ops_owned[0] = false;
         o->opmem[0].typ = QPMS_TMATRIX_OPERATION_LRMATRIX;
         o->opmem[0].op.lrmatrix.m = m;
+        o->opmem[0].op.lrmatrix.owns_m = true;
         o->opmem[0].op.lrmatrix.m_size = d * d;
         o->ops[1] = o->opmem;
         o->ops_owned[1] = true;
@@ -462,6 +465,9 @@ qpms_scatsys_at_omega_t *qpms_scatsys_apply_symmetry(const qpms_scatsys_t *orig,
 
 void qpms_scatsys_free(qpms_scatsys_t *ss) {
   if(ss) {
+    QPMS_ASSERT(ss->tm);
+    for(qpms_ss_tmi_t tmi = 0; tmi < ss->tm_count; ++tmi) 
+        qpms_tmatrix_operation_clear(&ss->tm[tmi].op); 
     free(ss->tm);
     free(ss->tmg);
     free(ss->p);
@@ -471,8 +477,11 @@ void qpms_scatsys_free(qpms_scatsys_t *ss) {
     free(ss->otspace);
     free(ss->p_orbitinfo);
     free(ss->orbit_types);
+    free(ss->saecv_ot_offsets);
     free(ss->saecv_sizes);
     free(ss->p_by_orbit);
+    if(ss->tbooster)
+      qpms_scatsys_translation_booster_free(ss->tbooster);
     qpms_trans_calculator_free(ss->c);
   }
   free(ss);
@@ -519,15 +528,26 @@ qpms_scatsys_at_omega_t *qpms_scatsys_at_omega(const qpms_scatsys_t *ss,
   for (qpms_ss_tmgi_t tmgi = 0; tmgi < ss->tmg_count; ++tmgi)
     qpms_tmatrix_free(tmatrices_preop[tmgi]);
   free(tmatrices_preop);
+  ssw->translation_cache= NULL;
   return ssw;
 }
 
+int qpms_ssw_create_translation_cache(qpms_scatsys_at_omega_t *ssw) {
+  if(!ssw->translation_cache)
+    if(ssw->ss->tbooster) 
+      ssw->translation_cache = qpms_scatsysw_translation_booster_create(ssw);
+  QPMS_ASSERT(ssw->translation_cache);
+  return 0;
+}
+
 void qpms_scatsys_at_omega_free(qpms_scatsys_at_omega_t *ssw) {
   if (ssw) {
     if(ssw->tm) 
      for(qpms_ss_tmi_t i = 0; i < ssw->ss->tm_count; ++i) 
       qpms_tmatrix_free(ssw->tm[i]); 
     free(ssw->tm);
+    if(ssw->translation_cache)
+      qpms_scatsysw_translation_booster_free(ssw->translation_cache);
   }
   free(ssw);
 }
@@ -667,25 +687,16 @@ complex double *qpms_orbit_irrep_basis(size_t *basis_size,
   complex double *U; QPMS_CRASHING_MALLOC(U, n*n*N*N*sizeof(complex double));
   double *s; QPMS_CRASHING_MALLOC(s, n*N*sizeof(double)); 
 
-  int info = LAPACKE_zgesdd(LAPACK_ROW_MAJOR,
+  QPMS_ENSURE_SUCCESS(LAPACKE_zgesdd(LAPACK_ROW_MAJOR,
       'A', // jobz; overwrite projector with left sg.vec. and write right into V_H
       n*N /* m */, n*N /* n */, projector /* a */, n*N /* lda */,
       s /* s */, U /* u */, n*N /* ldu, irrelev. */, V_H /* vt */,
-      n*N /* ldvt */);
-  if (info) qpms_pr_error_at_flf(__FILE__, __LINE__, __func__,
-        "Something went wrong with the SVD.");
-
+      n*N /* ldvt */));
 
   size_t bs;
   for(bs = 0; bs < n*N; ++bs) {
-#if 0
-    qpms_pr_debug_at_flf(__FILE__, __LINE__, __func__,
-        "%d. irrep, %zd. SV: %.16lf", (int) iri, bs, s[bs]);
-#endif
-    if(s[bs] > 1 + SVD_ATOL) qpms_pr_error_at_flf(__FILE__, __LINE__, __func__,
-        "%zd. SV too large: %.16lf", bs, s[bs]);
-    if(s[bs] > SVD_ATOL && fabs(1-s[bs]) > SVD_ATOL) 
-      qpms_pr_error_at_flf(__FILE__, __LINE__, __func__,
+    QPMS_ENSURE(s[bs] <= 1 + SVD_ATOL, "%zd. SV too large: %.16lf", bs, s[bs]);
+    QPMS_ENSURE(!(s[bs] > SVD_ATOL && fabs(1-s[bs]) > SVD_ATOL),
         "%zd. SV in the 'wrong' interval: %.16lf", bs, s[bs]);
     if(s[bs] < SVD_ATOL) break;
   }
@@ -694,6 +705,7 @@ complex double *qpms_orbit_irrep_basis(size_t *basis_size,
   if(newtarget) QPMS_CRASHING_REALLOC(target, bs*N*n*sizeof(complex double));
   if(basis_size) *basis_size = bs;
 
+  free(s);
   free(U);
   free(V_H);
   free(projector);
@@ -1110,6 +1122,8 @@ complex double *qpms_scatsysw_build_modeproblem_matrix_full(
     const qpms_scatsys_at_omega_t *ssw
     )
 {
+  if (ssw->translation_cache)
+    return qpms_scatsysw_build_modeproblem_matrix_full_boosted(target, ssw);
   const complex double k = ssw->wavenumber;
   const qpms_scatsys_t *ss = ssw->ss;
   const size_t full_len = ss->fecv_size;
@@ -1386,14 +1400,6 @@ complex double *qpms_scatsysw_build_modeproblem_matrix_irrep_packed_orbitorderR(
   return target_packed;
 }
 
-struct qpms_scatsysw_build_modeproblem_matrix_irrep_packed_parallelR_thread_arg{
-  const qpms_scatsys_at_omega_t *ssw;
-  qpms_ss_pi_t *opistartR_ptr;
-  pthread_mutex_t *opistartR_mutex;
-  qpms_iri_t iri;
-  complex double *target_packed;
-};
-
 static void *qpms_scatsysw_build_modeproblem_matrix_irrep_packed_parallelR_thread(void *arg)
 {
   const struct qpms_scatsysw_build_modeproblem_matrix_irrep_packed_parallelR_thread_arg 
@@ -1512,9 +1518,6 @@ static void *qpms_scatsysw_build_modeproblem_matrix_irrep_packed_parallelR_threa
         }
       }
     }
-
-
-
   }
   free(tmp);
   free(Sblock);
@@ -1644,9 +1647,6 @@ static void *qpms_scatsys_build_translation_matrix_e_irrep_packed_parallelR_thre
         }
       }
     }
-
-
-
   }
   free(tmp);
   free(Sblock);
@@ -1716,6 +1716,7 @@ complex double *qpms_scatsysw_build_modeproblem_matrix_irrep_packed(
     const qpms_scatsys_at_omega_t *ssw, qpms_iri_t iri
     )
 {
+  const _Bool use_translation_cache = (ssw->translation_cache != NULL);
   const size_t packedlen = ssw->ss->saecv_sizes[iri];
   if (!packedlen) // THIS IS A BIT PROBLEMATIC, TODO how to deal with empty irreps?
     return target_packed; 
@@ -1748,7 +1749,9 @@ complex double *qpms_scatsysw_build_modeproblem_matrix_irrep_packed(
   pthread_t thread_ids[nthreads];
   for(long thi = 0; thi < nthreads; ++thi)
     QPMS_ENSURE_SUCCESS(pthread_create(thread_ids + thi, NULL,
-      qpms_scatsysw_build_modeproblem_matrix_irrep_packed_parallelR_thread,
+      use_translation_cache 
+        ? qpms_scatsysw_build_modeproblem_matrix_irrep_packed_parallelR_thread_boosted
+        : qpms_scatsysw_build_modeproblem_matrix_irrep_packed_parallelR_thread,
       (void *) &arg));
   for(long thi = 0; thi < nthreads; ++thi) {
     void *retval;
@@ -1804,7 +1807,6 @@ complex double *qpms_scatsysw_apply_Tmatrices_full(
 }
 
 
-
 ccart3_t qpms_scatsys_eval_E(const qpms_scatsys_t *ss, 
     const complex double *cvf, const cart3_t where,
     const complex double k) {
@@ -1897,3 +1899,55 @@ complex double *qpms_scatsys_scatter_solve(
   return f;
 }
 
+struct qpms_scatsys_finite_eval_Beyn_ImTS_param {
+  const qpms_scatsys_t *ss;
+  qpms_iri_t iri;
+};
+
+/// Wrapper for Beyn algorithm (non-periodic system)
+static int qpms_scatsys_finite_eval_Beyn_ImTS(complex double *target,
+    size_t m, complex double omega, void *params) {
+  const struct qpms_scatsys_finite_eval_Beyn_ImTS_param *p = params;
+  qpms_scatsys_at_omega_t *ssw = qpms_scatsys_at_omega(p->ss, omega);
+  QPMS_ENSURE(ssw != NULL, "qpms_scatsys_at_omega() returned NULL");
+  if(p->ss->tbooster) qpms_ssw_create_translation_cache(ssw);
+  if (p->iri == QPMS_NO_IRREP) {
+    QPMS_ASSERT(m == p->ss->fecv_size);
+    QPMS_ENSURE(NULL != qpms_scatsysw_build_modeproblem_matrix_full(
+          target, ssw),
+      "qpms_scatsysw_build_modeproblem_matrix_full() returned NULL");
+  } else {
+    QPMS_ASSERT(m == p->ss->saecv_sizes[p->iri]);
+    QPMS_ENSURE(NULL != qpms_scatsysw_build_modeproblem_matrix_irrep_packed(
+          target, ssw, p->iri),
+      "qpms_scatsysw_build_modeproblem_matrix_irrep_packed() returned NULL");
+  }
+  qpms_scatsys_at_omega_free(ssw);
+  return QPMS_SUCCESS;
+}
+
+beyn_result_t *qpms_scatsys_finite_find_eigenmodes(
+    const qpms_scatsys_t * const ss, const qpms_iri_t iri,
+    complex double omega_centre, double omega_rr, double omega_ri, 
+    size_t contour_npoints, 
+    double rank_tol, size_t rank_sel_min, double res_tol) {
+  size_t n; // matrix dimension
+  if (qpms_iri_is_valid(ss->sym, iri)) {
+    n = ss->saecv_sizes[iri];
+  } else if (iri == QPMS_NO_IRREP) {
+    n = ss->fecv_size;
+  } else QPMS_WTF;
+
+  beyn_contour_t *contour = beyn_contour_ellipse(omega_centre,
+      omega_rr, omega_ri, contour_npoints);
+  
+  struct qpms_scatsys_finite_eval_Beyn_ImTS_param p = {ss, iri};
+  beyn_result_t *result = beyn_solve(n, n /* possibly make smaller? */,
+      qpms_scatsys_finite_eval_Beyn_ImTS, NULL, (void *) &p,
+      contour, rank_tol, rank_sel_min, res_tol);
+  QPMS_ENSURE(result != NULL, "beyn_solve() returned NULL");
+
+  free(contour);
+  return result;
+}
+

qpms/scatsystem.h

@@ -133,7 +133,7 @@ typedef struct qpms_ss_derived_tmatrix_t {
 
 
 struct qpms_trans_calculator;
-struct qpms_epsmu_generator_t;
+struct qpms_scatsys_translation_booster;
 
 typedef struct qpms_scatsys_t {
 	struct qpms_epsmu_generator_t medium; ///< Optical properties of the background medium.
@@ -188,8 +188,16 @@ typedef struct qpms_scatsys_t {
 	char *otspace_end;
 	double lenscale; // radius of the array, used as a relative tolerance measure
 	struct qpms_trans_calculator *c;
+	// Internal metadata for faster translation matrix evaluation
+	struct qpms_scatsys_translation_booster *tbooster;
+
 } qpms_scatsys_t;
 
+/// Returns true if ss has the translation caching metadata populated.
+static inline _Bool qpms_scatsys_has_translation_cache(const qpms_scatsys_t *ss) {
+	return ss->tbooster != NULL;
+}
+
 /// Retrieve the bspec of \a tmi'th element of \a ss->tm.
 static inline const qpms_vswf_set_spec_t *qpms_ss_bspec_tmi(const qpms_scatsys_t *ss, qpms_ss_tmi_t tmi) {
 	return ss->tmg[ss->tm[tmi].tmgi].spec;
@@ -200,6 +208,9 @@ static inline const qpms_vswf_set_spec_t *qpms_ss_bspec_pi(const qpms_scatsys_t
 	return ss->tmg[ss->tm[ss->p[pi].tmatrix_id].tmgi].spec;
 }
 
+struct qpms_scatsysw_translation_booster;
+void qpms_scatsysw_translation_booster_free(struct qpms_scatsysw_translation_booster *);
+
 typedef struct qpms_scatsys_at_omega_t {
 	const qpms_scatsys_t *ss; ///< Parent scattering system.
 	/// T-matrices from \a ss, evaluated at \a omega.
@@ -210,8 +221,11 @@ typedef struct qpms_scatsys_at_omega_t {
 	complex double omega; ///< Angular frequency
 	qpms_epsmu_t medium; ///< Background medium optical properties at the given frequency
 	complex double wavenumber; ///< Background medium wavenumber
+
+	struct qpms_scatsysw_translation_booster *translation_cache; ///< (private) cache to speedup translations
 } qpms_scatsys_at_omega_t;
 
+
 /// Creates a new scatsys by applying a symmetry group onto a "proto-scatsys", copying particles if needed.
 /** In fact, it copies everything except the vswf set specs and qpms_abstract_tmatrix_t instances,
  * so keep them alive until scatsys is destroyed.
@@ -261,6 +275,34 @@ void qpms_scatsys_at_omega_free(qpms_scatsys_at_omega_t *ssw);
 qpms_scatsys_at_omega_t *qpms_scatsys_at_omega(const qpms_scatsys_t *ss,
 		complex double omega);
 
+/// Determines behaviour of qpms_ss_create_translation_cache().
+typedef enum qpms_ss_caching_mode {
+	/// Don't create the translation operator cache.
+	/** Use this if the particle positions are random. */
+	QPMS_SS_CACHE_NEVER, 
+	/// Always create the translation operator cache.
+	/** Use this for highly regular large finite structures. */
+	QPMS_SS_CACHE_ALWAYS, 
+	/// Evaluate the need of caching automatically.
+	QPMS_SS_CACHE_AUTO, 
+	QPMS_SS_CACHE_DEFAULT = QPMS_SS_CACHE_AUTO
+} qpms_ss_caching_mode_t;
+
+/// Returns true if ssw has the translation operator cache populated.
+static inline _Bool qpms_scatsysw_has_translation_cache(const qpms_scatsys_at_omega_t *ssw) {
+	return ssw->translation_cache != NULL;
+}
+
+/// Creates some data structures for speeding up translation operator calculations.
+/** This is mostly useful for "finite lattices", where many pairs of nanoparticles
+ * share the same relative positions.
+ */
+int qpms_ss_create_translation_cache(qpms_scatsys_t *ss, qpms_ss_caching_mode_t m);
+
+/// Pre-calculates the "translation cache" of a qpms_scatsys_at_omega_t.
+/** If ssw->ss->tbooster is NULL, does nothing. */
+int qpms_ssw_create_translation_cache(qpms_scatsys_at_omega_t *ssw);
+
 /// Creates a "full" transformation matrix U that takes a full vector and projects it onto an symmetry adapted basis.
 /** Mostly as a reference and a debugging tool, as multiplicating these big matrices would be inefficient.
  * 
@@ -343,31 +385,43 @@ complex double *qpms_scatsys_build_translation_matrix_e_irrep_packed(
 		);
 
 /// Creates the full \f$ (I - TS) \f$ matrix of the scattering system.
+/**
+ * \returns \a target on success, NULL on error.
+ */
 complex double *qpms_scatsysw_build_modeproblem_matrix_full(
 		/// Target memory with capacity for ss->fecv_size**2 elements. If NULL, new will be allocated.
 		complex double *target,
 		const qpms_scatsys_at_omega_t *ssw
 		);
 /// Creates the mode problem matrix \f$ (I - TS) \f$ directly in the irrep-packed form.
+/**
+ * \returns \a target on success, NULL on error.
+ */
 complex double *qpms_scatsysw_build_modeproblem_matrix_irrep_packed(
 		/// Target memory with capacity for ss->fecv_size**2 elements. If NULL, new will be allocated.
 		complex double *target,
 		const qpms_scatsys_at_omega_t *ssw,
-		qpms_iri_t iri
+		qpms_iri_t iri ///< Index of the irreducible representation in ssw->ss->sym
 		);
 /// Alternative implementation of qpms_scatsysw_build_modeproblem_matrix_irrep_packed().
+/**
+ * \returns \a target on success, NULL on error.
+ */
 complex double *qpms_scatsysw_build_modeproblem_matrix_irrep_packed_orbitorderR(
 		/// Target memory with capacity for ss->fecv_size**2 elements. If NULL, new will be allocated.
 		complex double *target,
 		const qpms_scatsys_at_omega_t *ssw,
-		qpms_iri_t iri
+		qpms_iri_t iri ///< Index of the irreducible representation in ssw->ss->sym
 		);
 /// Alternative (serial reference) implementation of qpms_scatsysw_build_modeproblem_matrix_irrep_packed().
+/**
+ * \returns \a target on success, NULL on error.
+ */
 complex double *qpms_scatsysw_build_modeproblem_matrix_irrep_packed_serial(
 		/// Target memory with capacity for ss->fecv_size**2 elements. If NULL, new will be allocated.
 		complex double *target,
 		const qpms_scatsys_at_omega_t *ssw,
-		qpms_iri_t iri
+		qpms_iri_t iri ///< Index of the irreducible representation in ssw->ss->sym
 		);
 
 /// LU factorisation (LAPACKE_zgetrf) result holder.
@@ -504,6 +558,55 @@ complex double *qpms_scatsysw_apply_Tmatrices_full(
 		const qpms_scatsys_at_omega_t *ssw
 		);
 
+struct beyn_result_t; // See beyn.h for full definition
+
+/// Searches for finite scattering system's eigenmodes using Beyn's algorithm.
+/**
+ * Currently, elliptical contour is used.
+ *
+ * TODO In the future, this will probably support irrep decomposition as well,
+ * but it does not make much sense for periodic / small systems, as in their
+ * case the bottleneck is the T-matrix and translation matrix evaluation
+ * rather than the linear algebra.
+ */
+struct beyn_result_t *qpms_scatsys_finite_find_eigenmodes(
+		const qpms_scatsys_t *ss, 
+		/// A valid irrep index to search only in one irrep, or QPMS_NO_IRREP for solving the full system.
+		qpms_iri_t iri,
+		complex double omega_centre, ///< Center of the ellipse inside which the eigenfreqs are searched for.
+		double omega_rr, ///< Real half-axis of the ellipse inside which the eigenfreqs are searched for.
+		double omega_ri, ///< Imaginary half-axis of the ellipse inside which the eigenfreqs are searched for.
+		size_t contour_npoints, ///< Number of elliptic contour discretisation points (preferably even number)
+		double rank_tol, ///< (default: `1e-4`) TODO DOC.
+		size_t rank_sel_min, ///< Minimum number of eigenvalue candidates, even if they don't pass \a rank_tol.
+		double res_tol ///< (default: `0.0`) TODO DOC.
+		);
+
+
+#if 0
+/// Searches for scattering system's eigenmodes using Beyn's algorithm.
+/**
+ * Currently, elliptical contour is used.
+ *
+ * TODO In the future, this will probably support irrep decomposition as well,
+ * but it does not make much sense for periodic / small systems, as in their
+ * case the bottleneck is the T-matrix and translation matrix evaluation
+ * rather than the linear algebra.
+ */
+struct beyn_result_t *qpms_scatsys_find_eigenmodes(
+		const qpms_scatsys_t *ss,
+		double eta, ///< Ewald sum parameter
+		const double *beta_, ///< k-vector of corresponding dimensionality, NULL/ignored for finite system.
+		complex double omega_centre, ///< Center of the ellipse inside which the eigenfreqs are searched for.
+		double omega_rr, ///< Real half-axis of the ellipse inside which the eigenfreqs are searched for.
+		double omega_ri, ///< Imaginary half-axis of the ellipse inside which the eigenfreqs are searched for.
+		size_t contour_npoints, ///< Number of elliptic contour discretisation points (preferably even number)
+		double rank_tol, ///< (default: `1e-4`) TODO DOC.
+		size_t rank_sel_min, ///< Minimum number of eigenvalue candidates, even if they don't pass \a rank_tol.
+		double res_tol ///< (default: `0.0`) TODO DOC.
+		);
+#endif
+
 
 #if 0
 /// Creates a (partial) incident field vector in the symmetry-adapted basis, given a function that evaluates the field expansions at points.

qpms/tmatrices.c

@@ -429,12 +429,12 @@ qpms_errno_t qpms_read_scuff_tmatrix(
     switch(PAlpha) {
       case 0: TAlpha = QPMS_VSWF_MAGNETIC; break;
       case 1: TAlpha = QPMS_VSWF_ELECTRIC; break;
-      default: assert(0);
+      default: QPMS_WTF;
     }
     switch(PBeta) {
       case 0: TBeta = QPMS_VSWF_MAGNETIC; break;
       case 1: TBeta = QPMS_VSWF_ELECTRIC; break;
-      default: assert(0);
+      default: QPMS_WTF;
     }
     qpms_uvswfi_t srcui = qpms_tmn2uvswfi(TAlpha, MAlpha, LAlpha),
                   destui = qpms_tmn2uvswfi(TBeta, MBeta, LBeta);

qpms/translations.c

@@ -13,6 +13,7 @@
 #include <gsl/gsl_sf_coupling.h>
 #include "qpms_error.h"
 #include "normalisation.h"
+#include "translations_inlines.h"
 
 /*
  * Define macros with additional factors that "should not be there" according
@@ -289,8 +290,8 @@ void qpms_trans_calculator_free(qpms_trans_calculator *c) {
   free(c->A_multipliers);
   free(c->B_multipliers[0]);
   free(c->B_multipliers);
-#ifdef LATTICESUMS
-  qpms_ewald3_constants_free(e3c);
+#ifdef LATTICESUMS32
+  qpms_ewald3_constants_free(c->e3c);
 #endif
   free(c->legendre0);
   free(c);
@@ -509,8 +510,7 @@ qpms_trans_calculator
 }
 
 static inline complex double qpms_trans_calculator_get_A_precalcbuf(const qpms_trans_calculator *c,
-    int m, int n, int mu, int nu, csph_t kdlj,
-    bool r_ge_d, qpms_bessel_t J,
+    int m, int n, int mu, int nu, double kdlj_phi,
     const complex double *bessel_buf, const double *legendre_buf) {
   TROPS_ONLY_EIMF_IMPLEMENTED(c->normalisation);
   size_t i = qpms_trans_calculator_index_mnmunu(c, m, n, mu, nu);
@@ -523,9 +523,9 @@ static inline complex double qpms_trans_calculator_get_A_precalcbuf(const qpms_t
     double Pp = legendre_buf[gsl_sf_legendre_array_index(p, abs(mu-m))];
     complex double zp = bessel_buf[p];
     complex double multiplier = c->A_multipliers[i][q];
-    ckahanadd(&sum, &kahanc, Pp * zp *  multiplier);
+    ckahanadd(&sum, &kahanc, Pp * zp * multiplier);
   }
-  complex double eimf =  cexp(I*(mu-m)*kdlj.phi);
+  complex double eimf =  cexp(I*(mu-m)*kdlj_phi);
   return sum * eimf;
 }
 
@@ -545,12 +545,11 @@ complex double qpms_trans_calculator_get_A_buf(const qpms_trans_calculator *c,
         costheta,csphase,legendre_buf));
   QPMS_ENSURE_SUCCESS(qpms_sph_bessel_fill(J, n+nu+1, kdlj.r, bessel_buf));
   return qpms_trans_calculator_get_A_precalcbuf(c,m,n,mu,nu,
-      kdlj,r_ge_d,J,bessel_buf,legendre_buf);
+      kdlj.phi,bessel_buf,legendre_buf);
 }
 
 static inline complex double qpms_trans_calculator_get_B_precalcbuf(const qpms_trans_calculator *c,
-    int m, int n, int mu, int nu, csph_t kdlj,
-    bool r_ge_d, qpms_bessel_t J,
+    int m, int n, int mu, int nu, double kdlj_phi,
     const complex double *bessel_buf, const double *legendre_buf) {
   TROPS_ONLY_EIMF_IMPLEMENTED(c->normalisation);
   size_t i = qpms_trans_calculator_index_mnmunu(c, m, n, mu, nu);
@@ -565,7 +564,7 @@ static inline complex double qpms_trans_calculator_get_B_precalcbuf(const qpms_t
     complex double multiplier = c->B_multipliers[i][q-BQ_OFFSET];
     ckahanadd(&sum, &kahanc, Pp_ * zp_ * multiplier);
   }
-  complex double eimf =  cexp(I*(mu-m)*kdlj.phi);
+  complex double eimf =  cexp(I*(mu-m)*kdlj_phi);
   return sum * eimf;
 }
 
@@ -584,7 +583,7 @@ complex double qpms_trans_calculator_get_B_buf(const qpms_trans_calculator *c,
         costheta,csphase,legendre_buf));
   QPMS_ENSURE_SUCCESS(qpms_sph_bessel_fill(J, n+nu+1, kdlj.r, bessel_buf));
   return qpms_trans_calculator_get_B_precalcbuf(c,m,n,mu,nu,
-      kdlj,r_ge_d,J,bessel_buf,legendre_buf);
+      kdlj.phi,bessel_buf,legendre_buf);
 }
 
 int qpms_trans_calculator_get_AB_buf_p(const qpms_trans_calculator *c,
@@ -604,12 +603,38 @@ int qpms_trans_calculator_get_AB_buf_p(const qpms_trans_calculator *c,
         costheta,-1,legendre_buf));
   QPMS_ENSURE_SUCCESS(qpms_sph_bessel_fill(J, n+nu+1, kdlj.r, bessel_buf));
   *Adest = qpms_trans_calculator_get_A_precalcbuf(c,m,n,mu,nu,
-      kdlj,r_ge_d,J,bessel_buf,legendre_buf);
+      kdlj.phi,bessel_buf,legendre_buf);
   *Bdest = qpms_trans_calculator_get_B_precalcbuf(c,m,n,mu,nu,
-      kdlj,r_ge_d,J,bessel_buf,legendre_buf);
+      kdlj.phi,bessel_buf,legendre_buf);
   return 0;
 }
 
+int qpms_trans_calculator_get_AB_arrays_precalcbuf(const qpms_trans_calculator *c,
+    qpms_y_t lMax, complex double *Adest, complex double *Bdest,
+    size_t deststride, size_t srcstride, double kdlj_phi,
+    const complex double *bessel_buf, const double *legendre_buf) {
+  if(lMax == 0) lMax = c->lMax;
+  QPMS_ASSERT(lMax <= c->lMax);
+  size_t desti = 0, srci = 0;
+  for (int n = 1; n <= lMax; ++n) for (int m = -n; m <= n; ++m) {
+    for (int nu = 1; nu <= lMax; ++nu) for (int mu = -nu; mu <= nu; ++mu) {
+#ifndef NDEBUG
+      size_t assertindex = qpms_trans_calculator_index_mnmunu(c,m,n,mu,nu);
+#endif
+      assert(assertindex == desti*c->nelem + srci);
+      *(Adest + deststride * desti + srcstride * srci) = 
+        qpms_trans_calculator_get_A_precalcbuf(c,m,n,mu,nu,
+            kdlj_phi, bessel_buf, legendre_buf);
+      *(Bdest + deststride * desti + srcstride * srci) = 
+        qpms_trans_calculator_get_B_precalcbuf(c,m,n,mu,nu,
+            kdlj_phi,bessel_buf,legendre_buf);
+      ++srci;
+    }
+    ++desti;
+    srci = 0;
+  }
+  return 0;
+}
 
 int qpms_trans_calculator_get_AB_arrays_buf(const qpms_trans_calculator *c,
     complex double *Adest, complex double *Bdest,
@@ -631,26 +656,9 @@ int qpms_trans_calculator_get_AB_arrays_buf(const qpms_trans_calculator *c,
     QPMS_ENSURE_SUCCESS(gsl_sf_legendre_array_e(GSL_SF_LEGENDRE_NONE,2*c->lMax+1,
           costheta,-1,legendre_buf));
     QPMS_ENSURE_SUCCESS(qpms_sph_bessel_fill(J, 2*c->lMax+1, kdlj.r, bessel_buf));
-    size_t desti = 0, srci = 0;
-    for (int n = 1; n <= c->lMax; ++n) for (int m = -n; m <= n; ++m) {
-      for (int nu = 1; nu <= c->lMax; ++nu) for (int mu = -nu; mu <= nu; ++mu) {
-#ifndef NDEBUG
-        size_t assertindex = qpms_trans_calculator_index_mnmunu(c,m,n,mu,nu);
-#endif
-        assert(assertindex == desti*c->nelem + srci);
-        *(Adest + deststride * desti + srcstride * srci) = 
-          qpms_trans_calculator_get_A_precalcbuf(c,m,n,mu,nu,
-              kdlj,r_ge_d,J,bessel_buf,legendre_buf);
-        *(Bdest + deststride * desti + srcstride * srci) = 
-          qpms_trans_calculator_get_B_precalcbuf(c,m,n,mu,nu,
-              kdlj,r_ge_d,J,bessel_buf,legendre_buf);
-        ++srci;
-      }
-      ++desti;
-      srci = 0;
-    }
-    return 0;
   }
+  return qpms_trans_calculator_get_AB_arrays_precalcbuf(c, c->lMax, Adest, Bdest,
+      deststride, srcstride, kdlj.phi, bessel_buf, legendre_buf);
 }
 
 complex double qpms_trans_calculator_get_A(const qpms_trans_calculator *c,
@@ -712,20 +720,8 @@ qpms_errno_t qpms_trans_calculator_get_trans_array(const qpms_trans_calculator *
   qpms_errno_t retval = qpms_trans_calculator_get_AB_arrays(c,
       A[0], B[0], c->nelem, 1,
       kdlj, r_ge_d, J);
-  for (size_t desti = 0; desti < destspec->n; ++desti) {
-    qpms_y_t desty; qpms_vswf_type_t destt;
-    if(QPMS_SUCCESS != qpms_uvswfi2ty(destspec->ilist[desti], &destt, &desty))
-        qpms_pr_error_at_flf(__FILE__,__LINE__,__func__,
-          "Invalid u. vswf index %llx.", destspec->ilist[desti]);
-    for (size_t srci = 0; srci < srcspec->n; ++srci){
-      qpms_y_t srcy; qpms_vswf_type_t srct;
-      if(QPMS_SUCCESS != qpms_uvswfi2ty(srcspec->ilist[srci], &srct, &srcy))
-          qpms_pr_error_at_flf(__FILE__,__LINE__,__func__,
-            "Invalid u. vswf index %llx.", srcspec->ilist[srci]);
-      target[srci * srcstride + desti * deststride]
-        = (srct == destt) ? A[desty][srcy] : B[desty][srcy];
-    }
-  }
+  qpms_trans_array_from_AB(target, destspec, deststride, srcspec, srcstride,
+      A[0], B[0], c->lMax);
   return retval;
 }
 
@@ -762,6 +758,7 @@ qpms_errno_t qpms_trans_calculator_get_trans_array_e32_e(const qpms_trans_calcul
       A, Aerr, B, Berr, ldAB, 1, 
       eta, k, b1, b2, beta, particle_shift, maxR, maxK, parts);
   for (size_t desti = 0; desti < destspec->n; ++desti) { 
+    // TODO replace with (modified) qpms_trans_array_from_AB()
     qpms_y_t desty; qpms_vswf_type_t destt;
     if(QPMS_SUCCESS != qpms_uvswfi2ty(destspec->ilist[desti], &destt, &desty))
         qpms_pr_error_at_flf(__FILE__,__LINE__,__func__,

qpms/translations_inlines.h

@@ -0,0 +1,42 @@
+#ifndef TRANSLATIONS_INLINES_H
+#define TRANSLATIONS_INLINES_H
+#include "translations.h"
+#include "indexing.h"
+
+/// Rearranges the default-ordered "A,B" array elements into "bspec"-defined matrix.
+// TODO DOC
+static inline void qpms_trans_array_from_AB(
+		complex double *t,
+		const qpms_vswf_set_spec_t *const t_destspec,
+		const size_t t_deststride,
+		const qpms_vswf_set_spec_t *const t_srcspec,
+		const size_t t_srcstride,
+		const complex double *const A, const complex double *const B,
+		/// A and B matrices' lMax.
+		/** This also determines their size and stride: they are assumed to
+		 * be square matrices of size `nelem * nelem` where
+		 * `nelem = qpms_lMax2nelem(lMax_AB)`
+		 */
+		const qpms_l_t lMax_AB
+		) {
+	QPMS_PARANOID_ASSERT(lMax_AB >= t_srcspec->lMax && lMax_AB >= t_destspec->lMax);
+	const qpms_y_t nelem_AB = qpms_lMax2nelem(lMax_AB);
+	for (size_t desti = 0; desti < t_destspec->n; ++desti) {
+		qpms_y_t desty; qpms_vswf_type_t destt;
+		QPMS_ENSURE_SUCCESS_M(qpms_uvswfi2ty(t_destspec->ilist[desti], &destt, &desty),
+				"Invalid u. vswf index %llx.", t_destspec->ilist[desti]);
+		for (size_t srci = 0; srci < t_srcspec->n; ++srci){
+			qpms_y_t srcy; qpms_vswf_type_t srct;
+			QPMS_ENSURE_SUCCESS_M(qpms_uvswfi2ty(t_srcspec->ilist[srci], &srct, &srcy),
+					"Invalid u. vswf index %llx.", t_srcspec->ilist[srci]);                                                                t[srci * t_srcstride + desti * t_deststride]
+				= (srct == destt) ? A[desty*nelem_AB + srcy] : B[desty*nelem_AB + srcy];
+		}
+	}
+}
+
+int qpms_trans_calculator_get_AB_arrays_precalcbuf(const qpms_trans_calculator *c,
+		qpms_y_t lMax, complex double *Adest, complex double *Bdest,
+		size_t deststride, size_t srcstride, double kdlj_phi,
+		const complex double *bessel_buf, const double *legendre_buf);
+ 
+#endif