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chouse.c
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/* chouse.c CCMATH mathematics library source code.
*
* Copyright (C) 2000 Daniel A. Atkinson All rights reserved.
* This code may be redistributed under the terms of the GNU library
* public license (LGPL). ( See the lgpl.license file for details.)
* ------------------------------------------------------------------------
*/
#include <stdlib.h>
#include "ccmath.h"
void chouse(Cpx *a, double *d, double *dp, int n)
{
double sc, x, y;
Cpx cc, u, *q0;
int i, j, k, m, e;
Cpx *qw, *pc, *p;
q0 = (Cpx *)calloc(2 * n, sizeof(Cpx));
for (i = 0, p = q0 + n, pc = a; i < n; ++i, pc += n + 1)
*p++ = *pc;
for (j = 0, pc = a; j < n - 2; ++j, pc += n + 1) {
m = n - j - 1;
for (i = 1, sc = 0.; i <= m; ++i)
sc += pc[i].re * pc[i].re + pc[i].im * pc[i].im;
if (sc > 0.) {
sc = sqrt(sc);
p = pc + 1;
y = sc + (x = sqrt(p->re * p->re + p->im * p->im));
if (x > 0.) {
cc.re = p->re / x;
cc.im = p->im / x;
}
else {
cc.re = 1.;
cc.im = 0.;
}
x = 1. / sqrt(2. * sc * y);
y *= x;
for (i = 0, qw = pc + 1; i < m; ++i) {
q0[i].re = q0[i].im = 0.;
if (i) {
qw[i].re *= x;
qw[i].im *= -x;
}
else {
qw[0].re = y * cc.re;
qw[0].im = -y * cc.im;
}
}
for (i = 0, e = j + 2, p = pc + n + 1, y = 0.; i < m;
++i, p += e++) {
q0[i].re +=
(u.re = qw[i].re) * p->re - (u.im = qw[i].im) * p->im;
q0[i].im += u.re * p->im + u.im * p->re;
++p;
for (k = i + 1; k < m; ++k, ++p) {
q0[i].re += qw[k].re * p->re - qw[k].im * p->im;
q0[i].im += qw[k].im * p->re + qw[k].re * p->im;
q0[k].re += u.re * p->re + u.im * p->im;
q0[k].im += u.im * p->re - u.re * p->im;
}
y += u.re * q0[i].re + u.im * q0[i].im;
}
for (i = 0; i < m; ++i) {
q0[i].re -= y * qw[i].re;
q0[i].re += q0[i].re;
q0[i].im -= y * qw[i].im;
q0[i].im += q0[i].im;
}
for (i = 0, e = j + 2, p = pc + n + 1; i < m; ++i, p += e++) {
for (k = i; k < m; ++k, ++p) {
p->re -= qw[i].re * q0[k].re + qw[i].im * q0[k].im +
q0[i].re * qw[k].re + q0[i].im * qw[k].im;
p->im -= qw[i].im * q0[k].re - qw[i].re * q0[k].im +
q0[i].im * qw[k].re - q0[i].re * qw[k].im;
}
}
}
d[j] = pc->re;
dp[j] = sc;
}
d[j] = pc->re;
d[j + 1] = (pc + n + 1)->re;
u = *(pc + 1);
dp[j] = sqrt(u.re * u.re + u.im * u.im);
for (j = 0, pc = a, qw = q0 + n; j < n; ++j, pc += n + 1) {
*pc = qw[j];
for (i = 1, p = pc + n; i < n - j; ++i, p += n) {
pc[i].re = p->re;
pc[i].im = -p->im;
}
}
free(q0);
}
ccmath.h
Cpx
struct complex Cpx
Definition ccmath.h:41
chouse
void chouse(Cpx *a, double *d, double *dp, int n)
Definition chouse.c:12
complex::re
double re
Definition ccmath.h:39
complex::im
double im
Definition ccmath.h:39
x
#define x