diff --git a/qpms/lattices.py b/qpms/lattices.py
index 4595c27..80f1c12 100644
--- a/qpms/lattices.py
+++ b/qpms/lattices.py
@@ -55,8 +55,8 @@ class Scattering(object):
         self.N = self.positions.shape[0]
         self.k_0 = k_0
         self.lMax = lMax if lMax else nelem2lMax(TMatrices.shape[-1])
-        self.tc = trans_calculator(lMax)
-        nelem = lMax * (lMax + 2) #!
+        self.tc = trans_calculator(self.lMax)
+        nelem = self.lMax * (self.lMax + 2) #!
         self.nelem = nelem #!
         self.prepared = False
         self.TMatrices = np.broadcast_to(TMatrices, (self.N,2,nelem,2,nelem))
@@ -159,6 +159,7 @@ class Scattering(object):
         _time_e(btime, verbose)
         return ab
 
+"""
 class Scattering_2D_lattice_rectcells(Scattering):
     def __init__(self, rectcell_dims, rectcell_elem_positions, cellspec, k_0, rectcell_TMatrices = None, TMatrices = None, lMax = None, verbose=False, J_scat=3):
         '''
@@ -177,6 +178,7 @@ class Scattering_2D_lattice_rectcells(Scattering):
         self.nelem = nelem #!
         self.prepared = False
         self.TMatrices = np.broadcast_to(TMatrices, (self.N,2,nelem,2,nelem))   
+"""
 
 class Scattering_2D_zsym(Scattering):
     def __init__(self, positions, TMatrices, k_0, lMax = None, verbose=False, J_scat=3):
@@ -187,7 +189,7 @@ class Scattering_2D_zsym(Scattering):
         self.my, self.ny = get_mn_y(self.lMax)
         self.TE_NMz = (self.my + self.ny) % 2
         self.TM_NMz = 1 - self.TE_NMz
-        self.tc = trans_calculator(lMax)
+        self.tc = trans_calculator(self.lMax)
         # TODO možnost zadávat T-matice rovnou ve zhuštěné podobě
         TMatrices_TE = TMatrices[...,self.TE_NMz[:,nx],self.TE_yz[:,nx],self.TE_NMz[nx,:],self.TE_yz[nx,:]]
         TMatrices_TM = TMatrices[...,self.TM_NMz[:,nx],self.TM_yz[:,nx],self.TM_NMz[nx,:],self.TM_yz[nx,:]]
@@ -239,7 +241,7 @@ class Scattering_2D_zsym(Scattering):
         elif (TE_or_TM is None):
             EoMl = (0,1)
         sbtime = _time_b(verbose, step = 'Calculating interparticle translation coefficients')
-        kdji = cart2sph(self.positions[:,nx,:] - self.positions[nx,:,:])
+        kdji = cart2sph(self.positions[:,nx,:] - self.positions[nx,:,:], allow2d=True)
         kdji[:,:,0] *= self.k_0
         # get_AB array structure: [j,yj,i,yi]
         # FIXME I could save some memory by calculating only half of these coefficients
diff --git a/qpms/qpms_c.pyx b/qpms/qpms_c.pyx
index d2d9a8a..9915b81 100644
--- a/qpms/qpms_c.pyx
+++ b/qpms/qpms_c.pyx
@@ -482,9 +482,15 @@ cdef class trans_calculator:
         object get_A, get_B, get_AB
 
     def __cinit__(self, int lMax, int normalization = 1):
+        if (lMax <= 0):
+            raise ValueError('lMax has to be greater than 0.')
         self.c = qpms_trans_calculator_init(lMax, normalization)
+        if self.c is NULL:
+            raise MemoryError
 
     def __init__(self, int lMax, int normalization = 1):
+        if self.c is NULL:
+            raise MemoryError()
         self.get_A_data[0].c = self.c
         self.get_A_data[0].cmethod = <void *>qpms_trans_calculator_get_A_ext
         self.get_A_data_p[0] = &(self.get_A_data[0])
@@ -537,7 +543,8 @@ cdef class trans_calculator:
                 0 # unused
                 )
     def __dealloc__(self):
-        qpms_trans_calculator_free(self.c)
+        if self.c is not NULL:
+            qpms_trans_calculator_free(self.c)
         # TODO Reference counts to get_A, get_B, get_AB?
 
     def lMax(self):
diff --git a/qpms/qpms_p.py b/qpms/qpms_p.py
index 3e46173..f08e36a 100644
--- a/qpms/qpms_p.py
+++ b/qpms/qpms_p.py
@@ -48,14 +48,22 @@ def ujit(f):
 
 # Coordinate transforms for arrays of "arbitrary" shape
 #@ujit
-def cart2sph(cart,axis=-1):
-    if (cart.shape[axis] != 3):
-        raise ValueError("The converted array has to have dimension 3"
-                         " along the given axis")
-    [x, y, z] = np.split(cart,3,axis=axis)
-    r = np.linalg.norm(cart,axis=axis,keepdims=True)
-    r_zero = np.logical_not(r)
-    θ = np.arccos(z/(r+r_zero))
+def cart2sph(cart,axis=-1, allow2d=False):
+    if cart.shape[axis] == 3:
+        [x, y, z] = np.split(cart,3,axis=axis)    
+        r = np.linalg.norm(cart,axis=axis,keepdims=True)
+        r_zero = np.logical_not(r)
+        θ = np.arccos(z/(r+r_zero))
+    elif cart.shape[axis] == 2 and allow2d:
+        [x, y] = np.split(cart,2,axis=axis)
+        r = np.linalg.norm(cart,axis=axis,keepdims=True)
+        r_zero = np.logical_not(r)
+        θ = np.broadcast_to(np.pi/2, x.shape)
+    else:
+        raise ValueError("The converted array has to have dimension 3 "
+                         "(or 2 if allow2d==True)"
+                         " along the given axis, not %d" % cart.shape[axis])
+
     φ = np.arctan2(y,x) # arctan2 handles zeroes correctly itself
     return np.concatenate((r,θ,φ),axis=axis)
 
diff --git a/qpms/translations.c b/qpms/translations.c
index 82b95b4..07c493e 100644
--- a/qpms/translations.c
+++ b/qpms/translations.c
@@ -353,6 +353,7 @@ int qpms_trans_calculator_multipliers_B(qpms_normalization_t norm, complex doubl
 
 qpms_trans_calculator
 *qpms_trans_calculator_init (int lMax, qpms_normalization_t normalization) {
+	assert(lMax > 0);
 	qpms_trans_calculator *c = malloc(sizeof(qpms_trans_calculator));
 	c->lMax = lMax;
 	c->nelem = lMax * (lMax+2);