template_blas_idamax.h

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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_BLAS_IDAMAX_HEADER
00036 #define TEMPLATE_BLAS_IDAMAX_HEADER
00037 
00038 
00039 template<class Treal>
00040 integer template_blas_idamax(const integer *n, const Treal *dx, const integer *incx)
00041 {
00042     /* System generated locals */
00043     integer ret_val, i__1;
00044     Treal d__1;
00045     /* Local variables */
00046      Treal dmax__;
00047      integer i__, ix;
00048 /*     finds the index of element having max. absolute value.   
00049        jack dongarra, linpack, 3/11/78.   
00050        modified 3/93 to return if incx .le. 0.   
00051        modified 12/3/93, array(1) declarations changed to array(*)   
00052        Parameter adjustments */
00053     --dx;
00054     /* Function Body */
00055     ret_val = 0;
00056     if (*n < 1 || *incx <= 0) {
00057         return ret_val;
00058     }
00059     ret_val = 1;
00060     if (*n == 1) {
00061         return ret_val;
00062     }
00063     if (*incx == 1) {
00064         goto L20;
00065     }
00066 /*        code for increment not equal to 1 */
00067     ix = 1;
00068     dmax__ = absMACRO(dx[1]);
00069     ix += *incx;
00070     i__1 = *n;
00071     for (i__ = 2; i__ <= i__1; ++i__) {
00072         if ((d__1 = dx[ix], absMACRO(d__1)) <= dmax__) {
00073             goto L5;
00074         }
00075         ret_val = i__;
00076         dmax__ = (d__1 = dx[ix], absMACRO(d__1));
00077 L5:
00078         ix += *incx;
00079 /* L10: */
00080     }
00081     return ret_val;
00082 /*        code for increment equal to 1 */
00083 L20:
00084     dmax__ = absMACRO(dx[1]);
00085     i__1 = *n;
00086     for (i__ = 2; i__ <= i__1; ++i__) {
00087         if ((d__1 = dx[i__], absMACRO(d__1)) <= dmax__) {
00088             goto L30;
00089         }
00090         ret_val = i__;
00091         dmax__ = (d__1 = dx[i__], absMACRO(d__1));
00092 L30:
00093         ;
00094     }
00095     return ret_val;
00096 } /* idamax_ */
00097 
00098 #endif

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