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/* Copyright (C) 2002 Joseph A. Sarlo
**
** 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 2
** 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
**
** jsarlo@mambo.peabody.jhu.edu
*/
#include <stdlib.h>
#include <math.h>
#include <stdio.h>
#ifdef NT
#define M_PI 3.14159265358979323846
#endif
/* modified bessel function of zeroth order */
double i0(double x);
void fillHanning(float *vec, int n) {
int i;
float xShift = (float)n / 2;
float x;
for (i = 0; i < n; i++) {
x = (i - xShift) / xShift;
vec[i] = (float)(0.5 * (1 + cos(M_PI * x)));
}
}
void fillHamming(float *vec, int n) {
int i;
float xShift = (float)n / 2;
float x;
for (i = 0; i < n; i++) {
x = (i - xShift) / xShift;
vec[i] = (float)(0.54 + 0.46 * cos(M_PI * x));
}
}
void fillBlackman(float *vec, int n) {
int i;
float xShift = (float)n / 2;
float x;
for (i = 0; i < n; i++) {
x = (i - xShift) / xShift;
vec[i] = (float)(0.42 + (0.5 * cos(M_PI * x)) + (0.08 * cos (2 * M_PI * x)));
}
}
void fillConnes(float *vec, int n) {
int i;
float xShift = (float)n / 2;
float x;
for (i = 0; i < n; i++) {
x = (i - xShift) / xShift;
vec[i] = (float)((1 - (x * x)) * (1 - (x * x)));
}
}
void fillCosine(float *vec, int n) {
int i;
float xShift = (float)n / 2;
float x;
for (i = 0; i < n; i++) {
x = (i - xShift) / xShift;
vec[i] = (float)cos(M_PI * x / 2);
}
}
void fillWelch(float *vec, int n) {
int i;
float xShift = (float)n / 2;
float x;
for (i = 0; i < n; i++) {
x = (i - xShift) / xShift;
vec[i] = 1 - (x * x);
}
}
void fillBartlett(float *vec, int n) {
int i;
float xShift = (float)n / 2;
float x;
for (i = 0; i < n; i++) {
x = (i - xShift) / xShift;
vec[i] = (float)(1 - fabs(x));
}
}
void fillLanczos(float *vec, int n) {
int i;
float xShift = (float)n / 2;
float x;
for (i = 0; i < n; i++) {
x = (i - xShift) / xShift;
if (x == 0) {
vec[i] = 1;
}
else {
vec[i] = (float)(sin(M_PI * x) / (M_PI * x));
}
}
}
void fillGaussian(float *vec, int n, float delta) {
int i;
float xShift = (float)n / 2;
float x;
if (delta == 0) {
delta = 1;
}
for (i = 0; i < n; i++) {
x = (i - xShift) / xShift;
vec[i] = (float)(pow(2, (-1 * (x / delta) * (x / delta))));
}
}
void fillKaiser(float *vec, int n, float alpha) {
int i;
float xShift = (float)n / 2;
float x;
for (i = 0; i < n; i++) {
x = (i - xShift) / xShift;
vec[i] = (float)(i0(alpha * sqrt(1 - (x * x))) / i0(alpha));
}
}
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