159 lines
8.4 KiB
C
159 lines
8.4 KiB
C
#include "qpms_specfunc.h"
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#include "qpms_types.h"
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#include <gsl/gsl_sf_legendre.h>
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#include <gsl/gsl_math.h>
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#include <stdlib.h>
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#include "indexing.h"
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#include <string.h>
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// Legendre functions also for negative m, see DLMF 14.9.3
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qpms_errno_t qpms_legendre_deriv_y_fill(double *target, double *target_deriv, double x, qpms_l_t lMax,
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gsl_sf_legendre_t lnorm, double csphase)
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{
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size_t n = gsl_sf_legendre_array_n(lMax);
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double *legendre_tmp = malloc(n * sizeof(double));
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double *legendre_deriv_tmp = malloc(n * sizeof(double));
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int gsl_errno = gsl_sf_legendre_deriv_array_e(
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lnorm, (size_t)lMax, x, csphase, legendre_tmp,legendre_deriv_tmp);
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for (qpms_l_t l = 1; l <= lMax; ++l)
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for (qpms_m_t m = 0; m <= l; ++m) {
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qpms_y_t y = qpms_mn2y(m,l);
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size_t i = gsl_sf_legendre_array_index(l,m);
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target[y] = legendre_tmp[i];
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target_deriv[y] = legendre_deriv_tmp[i];
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}
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switch(lnorm) {
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case GSL_SF_LEGENDRE_NONE:
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for (qpms_l_t l = 1; l <= lMax; ++l)
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for (qpms_m_t m = 1; m <= l; ++m) {
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qpms_y_t y = qpms_mn2y(-m,l);
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size_t i = gsl_sf_legendre_array_index(l,m);
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// viz DLMF 14.9.3, čert ví, jak je to s cs fasí.
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double factor = exp(lgamma(l-m+1)-lgamma(l+m+1))*((m%2)?-1:1);
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target[y] = factor * legendre_tmp[i];
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target_deriv[y] = factor * legendre_deriv_tmp[i];
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}
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break;
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case GSL_SF_LEGENDRE_SCHMIDT:
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case GSL_SF_LEGENDRE_SPHARM:
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case GSL_SF_LEGENDRE_FULL:
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for (qpms_l_t l = 1; l <= lMax; ++l)
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for (qpms_m_t m = 1; m <= l; ++m) {
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qpms_y_t y = qpms_mn2y(-m,l);
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size_t i = gsl_sf_legendre_array_index(l,m);
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// viz DLMF 14.9.3, čert ví, jak je to s cs fasí.
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double factor = ((m%2)?-1:1); // this is the difference from the unnormalised case
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target[y] = factor * legendre_tmp[i];
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target_deriv[y] = factor * legendre_deriv_tmp[i];
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}
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break;
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default:
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abort(); //NI
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break;
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}
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free(legendre_tmp);
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free(legendre_deriv_tmp);
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return QPMS_SUCCESS;
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}
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qpms_errno_t qpms_legendre_deriv_y_get(double **target, double **dtarget, double x, qpms_l_t lMax, gsl_sf_legendre_t lnorm,
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double csphase)
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{
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*target = malloc(sizeof(double)*qpms_lMax2nelem(lMax));
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*dtarget = malloc(sizeof(double)*qpms_lMax2nelem(lMax));
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return qpms_legendre_deriv_y_fill(*target, *dtarget, x, lMax, lnorm, csphase);
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}
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qpms_pitau_t qpms_pitau_get(double theta, qpms_l_t lMax, qpms_normalisation_t norm)
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{
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const double csphase = qpms_normalisation_t_csphase(norm);
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norm = qpms_normalisation_t_normonly(norm);
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qpms_pitau_t res;
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qpms_y_t nelem = qpms_lMax2nelem(lMax);
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res.pi = malloc(nelem * sizeof(double));
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res.tau = malloc(nelem * sizeof(double));
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double ct = cos(theta), st = sin(theta);
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if (1 == fabs(ct)) { // singular case, use DLMF 14.8.2
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memset(res.pi, 0, nelem*sizeof(double));
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memset(res.tau, 0, nelem*sizeof(double));
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res.leg = calloc(nelem, sizeof(double));
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switch(norm) {
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case QPMS_NORMALISATION_XU:
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for (qpms_l_t l = 1; l <= lMax; ++l) {
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res.leg[qpms_mn2y(0, l)] = (l%2)?ct:1.;
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double p = l*(l+1)/2;
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const double n = 0.5;
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int lpar = (l%2)?-1:1;
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res.pi [qpms_mn2y(+1, l)] = -((ct>0) ? -1 : lpar) * p * csphase;
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res.pi [qpms_mn2y(-1, l)] = -((ct>0) ? -1 : lpar) * n * csphase;
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res.tau[qpms_mn2y(+1, l)] = ((ct>0) ? +1 : lpar) * p * csphase;
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res.tau[qpms_mn2y(-1, l)] = -((ct>0) ? +1 : lpar) * n * csphase;
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}
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break;
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case QPMS_NORMALISATION_TAYLOR:
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for (qpms_l_t l = 1; l <= lMax; ++l) {
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res.leg[qpms_mn2y(0, l)] = ((l%2)?ct:1.)*sqrt((2*l+1)*0.25*M_1_PI);
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int lpar = (l%2)?-1:1;
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double fl = 0.25 * sqrt((2*l+1)*l*(l+1)*M_1_PI);
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res.pi [qpms_mn2y(+1, l)] = -((ct>0) ? -1 : lpar) * fl * csphase;
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res.pi [qpms_mn2y(-1, l)] = -((ct>0) ? -1 : lpar) * fl * csphase;
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res.tau[qpms_mn2y(+1, l)] = ((ct>0) ? +1 : lpar) * fl * csphase;
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res.tau[qpms_mn2y(-1, l)] = -((ct>0) ? +1 : lpar) * fl * csphase;
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}
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break;
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case QPMS_NORMALISATION_POWER:
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for (qpms_l_t l = 1; l <= lMax; ++l) {
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res.leg[qpms_mn2y(0, l)] = ((l%2)?ct:1.)*sqrt((2*l+1)/(4*M_PI *l*(l+1)));
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int lpar = (l%2)?-1:1;
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double fl = 0.25 * sqrt((2*l+1)*M_1_PI);
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res.pi [qpms_mn2y(+1, l)] = -((ct>0) ? -1 : lpar) * fl * csphase;
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res.pi [qpms_mn2y(-1, l)] = -((ct>0) ? -1 : lpar) * fl * csphase;
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res.tau[qpms_mn2y(+1, l)] = ((ct>0) ? +1 : lpar) * fl * csphase;
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res.tau[qpms_mn2y(-1, l)] = -((ct>0) ? +1 : lpar) * fl * csphase;
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}
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break;
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default:
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abort();
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}
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}
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else { // cos(theta) in (-1,1), use normal calculation
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double *legder = malloc(sizeof(double)*qpms_lMax2nelem(lMax));
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res.leg = malloc(sizeof(double)*qpms_lMax2nelem(lMax));
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if (qpms_legendre_deriv_y_fill(res.leg, legder, ct, lMax,
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norm == QPMS_NORMALISATION_XU ? GSL_SF_LEGENDRE_NONE
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: GSL_SF_LEGENDRE_SPHARM, csphase))
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abort();
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if (norm == QPMS_NORMALISATION_POWER)
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/* for Xu (=non-normalized) and Taylor (=sph. harm. normalized)
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* the correct normalisation is already obtained from gsl_sf_legendre_deriv_array_e().
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* However, Kristensson ("power") normalisation differs from Taylor
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* by 1/sqrt(l*(l+1)) factor.
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*/
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for (qpms_l_t l = 1; l <= lMax; ++l) {
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double prefac = 1./sqrt(l*(l+1));
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for (qpms_m_t m = -l; m <= l; ++m) {
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res.leg[qpms_mn2y(m,l)] *= prefac;
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legder[qpms_mn2y(m,l)] *= prefac;
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}
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}
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for (qpms_l_t l = 1; l <= lMax; ++l) {
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for (qpms_m_t m = -l; m <= l; ++m) {
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res.pi [qpms_mn2y(m,l)] = m / st * res.leg[qpms_mn2y(m,l)];
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res.tau[qpms_mn2y(m,l)] = - st * legder[qpms_mn2y(m,l)];
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}
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}
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free(legder);
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}
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res.lMax = lMax;
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return res;
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}
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void qpms_pitau_free(qpms_pitau_t x) {
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free(x.leg);
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free(x.pi);
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free(x.tau);
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}
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