/* 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 3 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;

}