00001 /* ***************************************************** */ 00002 /* Compute the time mean and variance of a 2D field */ 00003 /* time_mean_variance_field_2d.c */ 00004 /* ***************************************************** */ 00005 /* Author: Christian Page, CERFACS, Toulouse, France. */ 00006 /* ***************************************************** */ 00011 /* LICENSE BEGIN 00012 00013 Copyright Cerfacs (Christian Page) (2015) 00014 00015 christian.page@cerfacs.fr 00016 00017 This software is a computer program whose purpose is to downscale climate 00018 scenarios using a statistical methodology based on weather regimes. 00019 00020 This software is governed by the CeCILL license under French law and 00021 abiding by the rules of distribution of free software. You can use, 00022 modify and/ or redistribute the software under the terms of the CeCILL 00023 license as circulated by CEA, CNRS and INRIA at the following URL 00024 "http://www.cecill.info". 00025 00026 As a counterpart to the access to the source code and rights to copy, 00027 modify and redistribute granted by the license, users are provided only 00028 with a limited warranty and the software's author, the holder of the 00029 economic rights, and the successive licensors have only limited 00030 liability. 00031 00032 In this respect, the user's attention is drawn to the risks associated 00033 with loading, using, modifying and/or developing or reproducing the 00034 software by the user in light of its specific status of free software, 00035 that may mean that it is complicated to manipulate, and that also 00036 therefore means that it is reserved for developers and experienced 00037 professionals having in-depth computer knowledge. Users are therefore 00038 encouraged to load and test the software's suitability as regards their 00039 requirements in conditions enabling the security of their systems and/or 00040 data to be ensured and, more generally, to use and operate it in the 00041 same conditions as regards security. 00042 00043 The fact that you are presently reading this means that you have had 00044 knowledge of the CeCILL license and that you accept its terms. 00045 00046 LICENSE END */ 00047 00048 00049 00050 00051 00052 00053 00054 #include <utils.h> 00055 00057 void 00058 time_mean_variance_field_2d(double *bufmean, double *bufvar, double *buf, int ni, int nj, int nt) { 00059 00069 int i; /* Loop counter */ 00070 int j; /* Loop counter */ 00071 int t; /* Loop counter */ 00072 00073 double sum; /* Temporary sum for buf */ 00074 double diff; /* Temporary difference for variance calculation */ 00075 00076 /* First calculate mean over time of a 2D field */ 00077 for (j=0; j<nj; j++) 00078 for (i=0; i<ni; i++) { 00079 sum = 0.0; 00080 for (t=0; t<nt; t++) 00081 sum += buf[i+j*ni+t*ni*nj]; 00082 bufmean[i+j*ni] = sum / (double) nt; 00083 } 00084 00085 /* Then calculate variance over time of a 2D field */ 00086 for (j=0; j<nj; j++) 00087 for (i=0; i<ni; i++) { 00088 sum = 0.0; 00089 for (t=0; t<nt; t++) { 00090 diff = buf[i+j*ni+t*ni*nj] - bufmean[i+j*ni]; 00091 sum += (diff * diff); 00092 bufvar[i+j*ni] = sqrtf(sum / (double) (nt-1)); 00093 } 00094 } 00095 } 00096