GRASS GIS 8 Programmer's Manual 8.3.2(2024)-exported
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hevmax.c
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1/* hevmax.c CCMATH mathematics library source code.
2 *
3 * Copyright (C) 2000 Daniel A. Atkinson All rights reserved.
4 * This code may be redistributed under the terms of the GNU library
5 * public license (LGPL). ( See the lgpl.license file for details.)
6 * ------------------------------------------------------------------------
7 */
8
9#include <stdlib.h>
10#include "ccmath.h"
11
12double hevmax(Cpx *a, Cpx *u, int n)
13{
14 Cpx *x, *p, h;
15
16 double e, ep, s, t, te = 1.e-12;
17
18 int k, j;
19
20 x = (Cpx *)calloc(n, sizeof(Cpx));
21 x[0].re = 1.;
22 e = 0.;
23 do {
24 for (k = 0, p = a, s = t = 0.; k < n; ++k) {
25 for (j = 0, h.re = h.im = 0.; j < n; ++j, ++p) {
26 h.re += p->re * x[j].re - p->im * x[j].im;
27 h.im += p->im * x[j].re + p->re * x[j].im;
28 }
29 s += h.re * h.re + h.im * h.im;
30 t += h.re * x[k].re + h.im * x[k].im;
31 u[k] = h;
32 }
33 ep = e;
34 e = s / t;
35 s = 1. / sqrt(s);
36 for (k = 0; k < n; ++k) {
37 u[k].re *= s;
38 u[k].im *= s;
39 x[k] = u[k];
40 }
41 } while (fabs(e - ep) > fabs(te * e));
42 free(x);
43 return e;
44}
double t
double hevmax(Cpx *a, Cpx *u, int n)
Definition hevmax.c:12
double re
Definition ccmath.h:39
double im
Definition ccmath.h:39
#define x