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/* hevmax.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"
double hevmax(Cpx *a, Cpx *u, int n)
{
Cpx *x, *p, h;
double e, ep, s, t, te = 1.e-12;
int k, j;
x = (Cpx *)calloc(n, sizeof(Cpx));
x[0].re = 1.;
e = 0.;
do {
for (k = 0, p = a, s = t = 0.; k < n; ++k) {
for (j = 0, h.re = h.im = 0.; j < n; ++j, ++p) {
h.re += p->re * x[j].re - p->im * x[j].im;
h.im += p->im * x[j].re + p->re * x[j].im;
}
s += h.re * h.re + h.im * h.im;
t += h.re * x[k].re + h.im * x[k].im;
u[k] = h;
}
ep = e;
e = s / t;
s = 1. / sqrt(s);
for (k = 0; k < n; ++k) {
u[k].re *= s;
u[k].im *= s;
x[k] = u[k];
}
} while (fabs(e - ep) > fabs(te * e));
free(x);
return e;
}
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