GRASS GIS 8 Programmer's Manual 8.2.1(2023)-exported
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#include <stdlib.h>
9#include "ccmath.h"
10double hevmax(Cpx * a, Cpx * u, int n)
11{
12 Cpx *x, *p, h;
13
14 double e, ep, s, t, te = 1.e-12;
15
16 int k, j;
17
18 x = (Cpx *) calloc(n, sizeof(Cpx));
19 x[0].re = 1.;
20 e = 0.;
21 do {
22 for (k = 0, p = a, s = t = 0.; k < n; ++k) {
23 for (j = 0, h.re = h.im = 0.; j < n; ++j, ++p) {
24 h.re += p->re * x[j].re - p->im * x[j].im;
25 h.im += p->im * x[j].re + p->re * x[j].im;
26 }
27 s += h.re * h.re + h.im * h.im;
28 t += h.re * x[k].re + h.im * x[k].im;
29 u[k] = h;
30 }
31 ep = e;
32 e = s / t;
33 s = 1. / sqrt(s);
34 for (k = 0; k < n; ++k) {
35 u[k].re *= s;
36 u[k].im *= s;
37 x[k] = u[k];
38 }
39 } while (fabs(e - ep) > fabs(te * e));
40 free(x);
41 return e;
42}
double t
double hevmax(Cpx *a, Cpx *u, int n)
Definition: hevmax.c:10
Definition: ccmath.h:38
double re
Definition: ccmath.h:38
double im
Definition: ccmath.h:38
#define x