template_lapack_lapy3.h

Go to the documentation of this file.
00001 /* Ergo, version 3.2, a program for linear scaling electronic structure
00002  * calculations.
00003  * Copyright (C) 2012 Elias Rudberg, Emanuel H. Rubensson, and Pawel Salek.
00004  * 
00005  * This program is free software: you can redistribute it and/or modify
00006  * it under the terms of the GNU General Public License as published by
00007  * the Free Software Foundation, either version 3 of the License, or
00008  * (at your option) any later version.
00009  * 
00010  * This program is distributed in the hope that it will be useful,
00011  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00012  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00013  * GNU General Public License for more details.
00014  * 
00015  * You should have received a copy of the GNU General Public License
00016  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
00017  * 
00018  * Primary academic reference:
00019  * Kohn−Sham Density Functional Theory Electronic Structure Calculations 
00020  * with Linearly Scaling Computational Time and Memory Usage,
00021  * Elias Rudberg, Emanuel H. Rubensson, and Pawel Salek,
00022  * J. Chem. Theory Comput. 7, 340 (2011),
00023  * <http://dx.doi.org/10.1021/ct100611z>
00024  * 
00025  * For further information about Ergo, see <http://www.ergoscf.org>.
00026  */
00027  
00028  /* This file belongs to the template_lapack part of the Ergo source 
00029   * code. The source files in the template_lapack directory are modified
00030   * versions of files originally distributed as CLAPACK, see the
00031   * Copyright/license notice in the file template_lapack/COPYING.
00032   */
00033  
00034 
00035 #ifndef TEMPLATE_LAPACK_LAPY3_HEADER
00036 #define TEMPLATE_LAPACK_LAPY3_HEADER
00037 
00038 
00039 template<class Treal>
00040 Treal template_lapack_lapy3(Treal *x, Treal *y, Treal *z__)
00041 {
00042 /*  -- LAPACK auxiliary routine (version 3.0) --   
00043        Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,   
00044        Courant Institute, Argonne National Lab, and Rice University   
00045        October 31, 1992   
00046 
00047 
00048     Purpose   
00049     =======   
00050 
00051     DLAPY3 returns sqrt(x**2+y**2+z**2), taking care not to cause   
00052     unnecessary overflow.   
00053 
00054     Arguments   
00055     =========   
00056 
00057     X       (input) DOUBLE PRECISION   
00058     Y       (input) DOUBLE PRECISION   
00059     Z       (input) DOUBLE PRECISION   
00060             X, Y and Z specify the values x, y and z.   
00061 
00062     ===================================================================== */
00063     /* System generated locals */
00064     Treal ret_val, d__1, d__2, d__3;
00065     /* Local variables */
00066      Treal xabs, yabs, zabs, w;
00067 
00068 
00069 
00070     xabs = absMACRO(*x);
00071     yabs = absMACRO(*y);
00072     zabs = absMACRO(*z__);
00073 /* Computing MAX */
00074     d__1 = maxMACRO(xabs,yabs);
00075     w = maxMACRO(d__1,zabs);
00076     if (w == 0.) {
00077         ret_val = 0.;
00078     } else {
00079 /* Computing 2nd power */
00080         d__1 = xabs / w;
00081 /* Computing 2nd power */
00082         d__2 = yabs / w;
00083 /* Computing 2nd power */
00084         d__3 = zabs / w;
00085         ret_val = w * template_blas_sqrt(d__1 * d__1 + d__2 * d__2 + d__3 * d__3);
00086     }
00087     return ret_val;
00088 
00089 /*     End of DLAPY3 */
00090 
00091 } /* dlapy3_ */
00092 
00093 #endif

Generated on Mon Sep 17 14:30:40 2012 for ergo by  doxygen 1.4.7