00001 /* Ergo, version 3.7, a program for linear scaling electronic structure 00002 * calculations. 00003 * Copyright (C) 2018 Elias Rudberg, Emanuel H. Rubensson, Pawel Salek, 00004 * and Anastasia Kruchinina. 00005 * 00006 * This program is free software: you can redistribute it and/or modify 00007 * it under the terms of the GNU General Public License as published by 00008 * the Free Software Foundation, either version 3 of the License, or 00009 * (at your option) any later version. 00010 * 00011 * This program is distributed in the hope that it will be useful, 00012 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 * GNU General Public License for more details. 00015 * 00016 * You should have received a copy of the GNU General Public License 00017 * along with this program. If not, see <http://www.gnu.org/licenses/>. 00018 * 00019 * Primary academic reference: 00020 * Ergo: An open-source program for linear-scaling electronic structure 00021 * calculations, 00022 * Elias Rudberg, Emanuel H. Rubensson, Pawel Salek, and Anastasia 00023 * Kruchinina, 00024 * SoftwareX 7, 107 (2018), 00025 * <http://dx.doi.org/10.1016/j.softx.2018.03.005> 00026 * 00027 * For further information about Ergo, see <http://www.ergoscf.org>. 00028 */ 00029 00030 /* This file belongs to the template_lapack part of the Ergo source 00031 * code. The source files in the template_lapack directory are modified 00032 * versions of files originally distributed as CLAPACK, see the 00033 * Copyright/license notice in the file template_lapack/COPYING. 00034 */ 00035 00036 00037 #ifndef TEMPLATE_LAPACK_LAPY2_HEADER 00038 #define TEMPLATE_LAPACK_LAPY2_HEADER 00039 00040 00041 template<class Treal> 00042 Treal template_lapack_lapy2(Treal *x, Treal *y) 00043 { 00044 /* -- LAPACK auxiliary routine (version 3.0) -- 00045 Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., 00046 Courant Institute, Argonne National Lab, and Rice University 00047 October 31, 1992 00048 00049 00050 Purpose 00051 ======= 00052 00053 DLAPY2 returns sqrt(x**2+y**2), taking care not to cause unnecessary 00054 overflow. 00055 00056 Arguments 00057 ========= 00058 00059 X (input) DOUBLE PRECISION 00060 Y (input) DOUBLE PRECISION 00061 X and Y specify the values x and y. 00062 00063 ===================================================================== */ 00064 /* System generated locals */ 00065 Treal ret_val, d__1; 00066 /* Local variables */ 00067 Treal xabs, yabs, w, z__; 00068 00069 00070 00071 xabs = absMACRO(*x); 00072 yabs = absMACRO(*y); 00073 w = maxMACRO(xabs,yabs); 00074 z__ = minMACRO(xabs,yabs); 00075 if (z__ == 0.) { 00076 ret_val = w; 00077 } else { 00078 /* Computing 2nd power */ 00079 d__1 = z__ / w; 00080 ret_val = w * template_blas_sqrt(d__1 * d__1 + 1.); 00081 } 00082 return ret_val; 00083 00084 /* End of DLAPY2 */ 00085 00086 } /* dlapy2_ */ 00087 00088 #endif