include/gsl/gsl_dht.h

0001 /* dht/gsl_dht.h
0002  *
0003  * Copyright (C) 1996, 1997, 1998, 1999, 2000 Gerard Jungman
0004  *
0005  * This program is free software; you can redistribute it and/or modify
0006  * it under the terms of the GNU General Public License as published by
0007  * the Free Software Foundation; either version 3 of the License, or (at
0008  * your option) any later version.
0009  *
0010  * This program is distributed in the hope that it will be useful, but
0011  * WITHOUT ANY WARRANTY; without even the implied warranty of
0012  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
0013  * General Public License for more details.
0014  *
0015  * You should have received a copy of the GNU General Public License
0016  * along with this program; if not, write to the Free Software
0017  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
0018  */
0019
0020 /* Author:  G. Jungman
0021  */
0022 #ifndef __GSL_DHT_H__
0023 #define __GSL_DHT_H__
0024
0025 #include <stdlib.h>
0026
0027 #undef __BEGIN_DECLS
0028 #undef __END_DECLS
0029 #ifdef __cplusplus
0030 # define __BEGIN_DECLS extern "C" {
0031 # define __END_DECLS }
0032 #else
0033 # define __BEGIN_DECLS /* empty */
0034 # define __END_DECLS /* empty */
0035 #endif
0036
0037 __BEGIN_DECLS
0038
0039
0040 struct gsl_dht_struct {
0041   size_t    size;  /* size of the sample arrays to be transformed    */
0042   double    nu;    /* Bessel function order                          */
0043   double    xmax;  /* the upper limit to the x-sampling domain       */
0044   double    kmax;  /* the upper limit to the k-sampling domain       */
0045   double *  j;     /* array of computed J_nu zeros, j_{nu,s} = j[s]  */
0046   double *  Jjj;   /* transform numerator, J_nu(j_i j_m / j_N)       */
0047   double *  J2;    /* transform denominator, J_{nu+1}^2(j_m)         */
0048 };
0049 typedef struct gsl_dht_struct gsl_dht;
0050
0051
0052 /* Create a new transform object for a given size
0053  * sampling array on the domain [0, xmax].
0054  */
0055 gsl_dht * gsl_dht_alloc(size_t size);
0056 gsl_dht * gsl_dht_new(size_t size, double nu, double xmax);
0057
0058 /* Recalculate a transform object for given values of nu, xmax.
0059  * You cannot change the size of the object since the internal
0060  * allocation is reused.
0061  */
0062 int gsl_dht_init(gsl_dht * t, double nu, double xmax);
0063
0064 /* The n'th computed x sample point for a given transform.
0065  * 0 <= n <= size-1
0066  */
0067 double gsl_dht_x_sample(const gsl_dht * t, int n);
0068
0069
0070 /* The n'th computed k sample point for a given transform.
0071  * 0 <= n <= size-1
0072  */
0073 double gsl_dht_k_sample(const gsl_dht * t, int n);
0074
0075
0076 /* Free a transform object.
0077  */
0078 void gsl_dht_free(gsl_dht * t);
0079
0080
0081 /* Perform a transform on a sampled array.
0082  * f_in[0] ... f_in[size-1] and similarly for f_out[]
0083  */
0084 int gsl_dht_apply(const gsl_dht * t, double * f_in, double * f_out);
0085
0086
0087 __END_DECLS
0088
0089 #endif /* __GSL_DHT_H__ */