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template_lapack_larnv.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_LAPACK_LARNV_HEADER
00036 #define TEMPLATE_LAPACK_LARNV_HEADER
00037 
00038 
00039 template<class Treal>
00040 int template_lapack_larnv(const integer *idist, integer *iseed, const integer *n, 
00041         Treal *x)
00042 {
00043 /*  -- LAPACK auxiliary routine (version 3.0) --   
00044        Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,   
00045        Courant Institute, Argonne National Lab, and Rice University   
00046        September 30, 1994   
00047 
00048 
00049     Purpose   
00050     =======   
00051 
00052     DLARNV returns a vector of n random real numbers from a uniform or   
00053     normal distribution.   
00054 
00055     Arguments   
00056     =========   
00057 
00058     IDIST   (input) INTEGER   
00059             Specifies the distribution of the random numbers:   
00060             = 1:  uniform (0,1)   
00061             = 2:  uniform (-1,1)   
00062             = 3:  normal (0,1)   
00063 
00064     ISEED   (input/output) INTEGER array, dimension (4)   
00065             On entry, the seed of the random number generator; the array   
00066             elements must be between 0 and 4095, and ISEED(4) must be   
00067             odd.   
00068             On exit, the seed is updated.   
00069 
00070     N       (input) INTEGER   
00071             The number of random numbers to be generated.   
00072 
00073     X       (output) DOUBLE PRECISION array, dimension (N)   
00074             The generated random numbers.   
00075 
00076     Further Details   
00077     ===============   
00078 
00079     This routine calls the auxiliary routine DLARUV to generate random   
00080     real numbers from a uniform (0,1) distribution, in batches of up to   
00081     128 using vectorisable code. The Box-Muller method is used to   
00082     transform numbers from a uniform to a normal distribution.   
00083 
00084     =====================================================================   
00085 
00086 
00087        Parameter adjustments */
00088     /* System generated locals */
00089     integer i__1, i__2, i__3;
00090     /* Local variables */
00091      integer i__;
00092      Treal u[128];
00093      integer il, iv;
00094      integer il2;
00095 
00096     --x;
00097     --iseed;
00098 
00099     /* Function Body */
00100     i__1 = *n;
00101     for (iv = 1; iv <= i__1; iv += 64) {
00102 /* Computing MIN */
00103         i__2 = 64, i__3 = *n - iv + 1;
00104         il = minMACRO(i__2,i__3);
00105         if (*idist == 3) {
00106             il2 = il << 1;
00107         } else {
00108             il2 = il;
00109         }
00110 
00111 /*        Call DLARUV to generate IL2 numbers from a uniform (0,1)   
00112           distribution (IL2 <= LV) */
00113 
00114         dlaruv_(&iseed[1], &il2, u);
00115 
00116         if (*idist == 1) {
00117 
00118 /*           Copy generated numbers */
00119 
00120             i__2 = il;
00121             for (i__ = 1; i__ <= i__2; ++i__) {
00122                 x[iv + i__ - 1] = u[i__ - 1];
00123 /* L10: */
00124             }
00125         } else if (*idist == 2) {
00126 
00127 /*           Convert generated numbers to uniform (-1,1) distribution */
00128 
00129             i__2 = il;
00130             for (i__ = 1; i__ <= i__2; ++i__) {
00131                 x[iv + i__ - 1] = u[i__ - 1] * 2. - 1.;
00132 /* L20: */
00133             }
00134         } else if (*idist == 3) {
00135 
00136 /*           Convert generated numbers to normal (0,1) distribution */
00137 
00138             i__2 = il;
00139             for (i__ = 1; i__ <= i__2; ++i__) {
00140                 x[iv + i__ - 1] = template_blas_sqrt(template_blas_log(u[(i__ << 1) - 2]) * -2.) * cos(u[(
00141                         i__ << 1) - 1] * 6.2831853071795864769252867663);
00142 /* L30: */
00143             }
00144         }
00145 /* L40: */
00146     }
00147     return 0;
00148 
00149 /*     End of DLARNV */
00150 
00151 } /* dlarnv_ */
00152 
00153 #endif