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/* solvps.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 "ccmath.h"
int solvps(double *a, double *b, int n)
{
double *p, *q, *r, *s, t;
int j, k;
for (j = 0, p = a; j < n; ++j, p += n + 1) {
for (q = a + j * n; q < p; ++q)
*p -= *q * *q;
if (*p <= 0.)
return -1;
*p = sqrt(*p);
for (k = j + 1, q = p + n; k < n; ++k, q += n) {
for (r = a + j * n, s = a + k * n, t = 0.; r < p;)
t += *r++ * *s++;
*q -= t;
*q /= *p;
}
}
for (j = 0, p = a; j < n; ++j, p += n + 1) {
for (k = 0, q = a + j * n; k < j;)
b[j] -= b[k++] * *q++;
b[j] /= *p;
}
for (j = n - 1, p = a + n * n - 1; j >= 0; --j, p -= n + 1) {
for (k = j + 1, q = p + n; k < n; q += n)
b[j] -= b[k++] * *q;
b[j] /= *p;
}
return 0;
}
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