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/* dht/gsl_dht.h
*
* Copyright (C) 1996, 1997, 1998, 1999, 2000 Gerard Jungman
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
/* Author: G. Jungman
*/
#ifndef __GSL_DHT_H__
#define __GSL_DHT_H__
#undef __BEGIN_DECLS
#undef __END_DECLS
#ifdef __cplusplus
# define __BEGIN_DECLS extern "C" {
# define __END_DECLS }
#else
# define __BEGIN_DECLS /* empty */
# define __END_DECLS /* empty */
#endif
__BEGIN_DECLS
struct gsl_dht_struct {
size_t size; /* size of the sample arrays to be transformed */
double nu; /* Bessel function order */
double xmax; /* the upper limit to the x-sampling domain */
double kmax; /* the upper limit to the k-sampling domain */
double * j; /* array of computed J_nu zeros, j_{nu,s} = j[s] */
double * Jjj; /* transform numerator, J_nu(j_i j_m / j_N) */
double * J2; /* transform denominator, J_{nu+1}^2(j_m) */
};
typedef struct gsl_dht_struct gsl_dht;
/* Create a new transform object for a given size
* sampling array on the domain [0, xmax].
*/
gsl_dht * gsl_dht_alloc(size_t size);
gsl_dht * gsl_dht_new(size_t size, double nu, double xmax);
/* Recalculate a transform object for given values of nu, xmax.
* You cannot change the size of the object since the internal
* allocation is reused.
*/
int gsl_dht_init(gsl_dht * t, double nu, double xmax);
/* The n'th computed x sample point for a given transform.
* 0 <= n <= size-1
*/
double gsl_dht_x_sample(const gsl_dht * t, int n);
/* The n'th computed k sample point for a given transform.
* 0 <= n <= size-1
*/
double gsl_dht_k_sample(const gsl_dht * t, int n);
/* Free a transform object.
*/
void gsl_dht_free(gsl_dht * t);
/* Perform a transform on a sampled array.
* f_in[0] ... f_in[size-1] and similarly for f_out[]
*/
int gsl_dht_apply(const gsl_dht * t, double * f_in, double * f_out);
__END_DECLS
#endif /* __GSL_DHT_H__ */
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