File: template_lapack_lapy3.h

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/* Ergo, version 3.8.2, a program for linear scaling electronic structure
 * calculations.
 * Copyright (C) 2023 Elias Rudberg, Emanuel H. Rubensson, Pawel Salek,
 * and Anastasia Kruchinina.
 * 
 * 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, see <http://www.gnu.org/licenses/>.
 * 
 * Primary academic reference:
 * Ergo: An open-source program for linear-scaling electronic structure
 * calculations,
 * Elias Rudberg, Emanuel H. Rubensson, Pawel Salek, and Anastasia
 * Kruchinina,
 * SoftwareX 7, 107 (2018),
 * <http://dx.doi.org/10.1016/j.softx.2018.03.005>
 * 
 * For further information about Ergo, see <http://www.ergoscf.org>.
 */
 
 /* This file belongs to the template_lapack part of the Ergo source 
  * code. The source files in the template_lapack directory are modified
  * versions of files originally distributed as CLAPACK, see the
  * Copyright/license notice in the file template_lapack/COPYING.
  */
 

#ifndef TEMPLATE_LAPACK_LAPY3_HEADER
#define TEMPLATE_LAPACK_LAPY3_HEADER


template<class Treal>
Treal template_lapack_lapy3(Treal *x, Treal *y, Treal *z__)
{
/*  -- LAPACK auxiliary routine (version 3.0) --   
       Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,   
       Courant Institute, Argonne National Lab, and Rice University   
       October 31, 1992   


    Purpose   
    =======   

    DLAPY3 returns sqrt(x**2+y**2+z**2), taking care not to cause   
    unnecessary overflow.   

    Arguments   
    =========   

    X       (input) DOUBLE PRECISION   
    Y       (input) DOUBLE PRECISION   
    Z       (input) DOUBLE PRECISION   
            X, Y and Z specify the values x, y and z.   

    ===================================================================== */
    /* System generated locals */
    Treal ret_val, d__1, d__2, d__3;
    /* Local variables */
     Treal xabs, yabs, zabs, w;



    xabs = absMACRO(*x);
    yabs = absMACRO(*y);
    zabs = absMACRO(*z__);
/* Computing MAX */
    d__1 = maxMACRO(xabs,yabs);
    w = maxMACRO(d__1,zabs);
    if (w == 0.) {
	ret_val = 0.;
    } else {
/* Computing 2nd power */
	d__1 = xabs / w;
/* Computing 2nd power */
	d__2 = yabs / w;
/* Computing 2nd power */
	d__3 = zabs / w;
	ret_val = w * template_blas_sqrt(d__1 * d__1 + d__2 * d__2 + d__3 * d__3);
    }
    return ret_val;

/*     End of DLAPY3 */

} /* dlapy3_ */

#endif