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/* ruinv.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.)
* ------------------------------------------------------------------------
*/
int ruinv(double *a, int n)
{
int j;
double fabs(double);
double tt, z, *p, *q, *r, *s, *t;
for (j = 0, tt = 0., p = a; j < n; ++j, p += n + 1)
if ((z = fabs(*p)) > tt)
tt = z;
tt *= 1.e-16;
for (j = 0, p = a; j < n; ++j, p += n + 1) {
if (fabs(*p) < tt)
return -1;
*p = 1. / *p;
for (q = a + j, t = a; q < p; t += n + 1, q += n) {
for (s = q, r = t, z = 0.; s < p; s += n)
z -= *s * *r++;
*q = z * *p;
}
}
return 0;
}
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