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/* blas/source_rotg.h
*
* Copyright (C) 1996, 1997, 1998, 1999, 2000 Gerard Jungman
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
{
const BASE roe = (fabs(*a) > fabs(*b) ? *a : *b);
const BASE scale = fabs(*a) + fabs(*b);
BASE r, z;
if (scale != 0.0) {
const BASE aos = *a / scale;
const BASE bos = *b / scale;
r = scale * sqrt(aos * aos + bos * bos);
r = GSL_SIGN(roe) * r;
*c = *a / r;
*s = *b / r;
z = 1.0;
if (fabs(*a) > fabs(*b))
z = *s;
if (fabs(*b) >= fabs(*a) && *c != 0.0)
z = 1.0 / (*c);
} else {
*c = 1.0;
*s = 0.0;
r = 0.0;
z = 0.0;
}
*a = r;
*b = z;
}
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