[37] | 1 | /* file: whistc.c |
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| 2 | ** description: MEX weighted histc function. |
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| 3 | ** author: Andrea Vedaldi |
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| 4 | **/ |
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| 5 | |
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| 6 | /* AUTORIGHTS |
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| 7 | Copyright (C) 2006 Andrea Vedaldi |
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| 8 | |
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| 9 | This file is part of VLUtil. |
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| 10 | |
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| 11 | VLUtil is free software; you can redistribute it and/or modify |
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| 12 | it under the terms of the GNU General Public License as published by |
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| 13 | the Free Software Foundation; either version 2, or (at your option) |
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| 14 | any later version. |
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| 15 | |
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| 16 | This program is distributed in the hope that it will be useful, |
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| 17 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 18 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 19 | GNU General Public License for more details. |
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| 20 | |
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| 21 | You should have received a copy of the GNU General Public License |
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| 22 | along with this program; if not, write to the Free Software Foundation, |
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| 23 | Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
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| 24 | */ |
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| 25 | |
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| 26 | /* 2006-2-17 NaN entries are correctly handled. See m-file for |
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| 27 | further infos. |
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| 28 | */ |
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| 29 | |
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| 30 | /** @file |
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| 31 | ** @brief HISTC MEX function implementation. |
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| 32 | **/ |
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| 33 | |
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| 34 | #include"mex.h" |
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| 35 | #include<stdlib.h> |
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| 36 | #include<math.h> |
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| 37 | |
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| 38 | /** WHISTC(X,W,EDGES) |
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| 39 | **/ |
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| 40 | #define min(a,b) ((a<b)?a:b) |
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| 41 | #define max(a,b) ((a<b)?b:a) |
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| 42 | |
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| 43 | typedef struct |
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| 44 | { |
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| 45 | double x ; |
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| 46 | double w ; |
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| 47 | } pairs_t ; |
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| 48 | |
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| 49 | /** Compares pairs of values. For natural ordering (ascending), it |
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| 50 | ** returns |
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| 51 | ** |
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| 52 | ** - < 0 if a < b |
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| 53 | ** - = 0 if a == b |
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| 54 | ** - > 0 if a > b |
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| 55 | ** |
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| 56 | ** We move NaNs to the end of the sorted sequence. In this way, they |
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| 57 | ** will be scanned when filling the tail of the histogram and |
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| 58 | ** skipped. |
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| 59 | **/ |
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| 60 | int |
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| 61 | cmp_pairs(const void* a, const void* b) |
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| 62 | { |
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| 63 | pairs_t* pa = (pairs_t*) a; |
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| 64 | pairs_t* pb = (pairs_t*) b; |
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| 65 | bool nana = isnan(pa->x) ; |
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| 66 | bool nanb = isnan(pb->x) ; |
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| 67 | if(!nana && !nanb) { |
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| 68 | double diff = pa->x - pb->x ; |
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| 69 | if(diff < 0) return -1 ; |
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| 70 | else if(diff > 0) return +1 ; |
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| 71 | else return 0 ; |
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| 72 | } else { |
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| 73 | /* consider nans to be bigger than any */ |
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| 74 | if(nana && nanb) return 0 ; /* both NaNs are euqal */ |
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| 75 | if(nanb) return -1 ; /* only b is NaN and thus it is bigger */ |
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| 76 | return 1 ; /* only a is NaN and this it is bigger */ |
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| 77 | } |
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| 78 | } |
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| 79 | |
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| 80 | /** @brief MEX driver. |
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| 81 | ** @param nout number of MATLAB output arguments. |
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| 82 | ** @param out MATLAB output arguments. |
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| 83 | ** @param nin number of MATLAB input arguments. |
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| 84 | ** @param in MATLAB input arguments. |
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| 85 | **/ |
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| 86 | void |
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| 87 | mexFunction(int nout, mxArray *out[], |
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| 88 | int nin, const mxArray *in[]) |
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| 89 | { |
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| 90 | int M, N, NE ; |
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| 91 | double* Xpt ; |
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| 92 | double* Wpt ; |
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| 93 | double* EDGESpt ; |
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| 94 | double* RESpt ; |
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| 95 | enum {X=0, W, EDGES} ; |
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| 96 | |
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| 97 | /** ----------------------------------------------------------------- |
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| 98 | ** Check the arguments |
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| 99 | ** -------------------------------------------------------------- */ |
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| 100 | if (nin != 3) { |
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| 101 | mexErrMsgTxt("Three arguments required."); |
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| 102 | } else if (nout > 1) { |
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| 103 | mexErrMsgTxt("Too many output arguments."); |
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| 104 | } |
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| 105 | |
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| 106 | if (!mxIsDouble(in[X]) || |
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| 107 | !mxIsDouble(in[W]) || |
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| 108 | !mxIsDouble(in[W])) { |
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| 109 | mexErrMsgTxt("The arguments must be real matrices.") ; |
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| 110 | } |
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| 111 | |
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| 112 | M = mxGetM(in[X]) ; |
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| 113 | N = mxGetN(in[X]) ; |
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| 114 | if( M != mxGetM(in[W]) || |
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| 115 | N != mxGetN(in[W]) ) { |
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| 116 | mexErrMsgTxt("X and W must have the same dimension.") ; |
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| 117 | } |
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| 118 | |
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| 119 | if(min( mxGetM(in[EDGES]), mxGetN(in[EDGES]) ) != 1) { |
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| 120 | mexErrMsgTxt("EDGES must be a vector.") ; |
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| 121 | } |
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| 122 | |
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| 123 | NE = max(mxGetM(in[EDGES]), mxGetN(in[EDGES])) ; |
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| 124 | |
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| 125 | if(NE < 2) { |
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| 126 | mexErrMsgTxt("At least two edges are required.\n") ; |
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| 127 | } |
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| 128 | |
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| 129 | Xpt = mxGetPr(in[X]) ; |
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| 130 | Wpt = mxGetPr(in[W]) ; |
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| 131 | EDGESpt = mxGetPr(in[EDGES]) ; |
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| 132 | |
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| 133 | { |
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| 134 | double x = EDGESpt[0] ; |
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| 135 | int j ; |
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| 136 | int ok = 1 ; |
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| 137 | for(j = 1 ; j < NE ; ++j) { |
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| 138 | ok &= (x < EDGESpt[j]) ; |
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| 139 | x = EDGESpt[j] ; |
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| 140 | } |
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| 141 | if(!ok) mexErrMsgTxt("EDGES must be increasing.") ; |
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| 142 | } |
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| 143 | |
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| 144 | /*if(nout == 0) return ;*/ |
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| 145 | |
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| 146 | /* If the input is a vector, make it a column. */ |
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| 147 | if(M == 1) { |
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| 148 | M = N ; |
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| 149 | N = 1 ; |
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| 150 | } |
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| 151 | |
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| 152 | /* Alloc the result. */ |
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| 153 | out[0] = mxCreateDoubleMatrix(NE, N, mxREAL) ; |
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| 154 | RESpt = mxGetPr(out[0]) ; |
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| 155 | |
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| 156 | /** ----------------------------------------------------------------- |
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| 157 | ** Do the job |
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| 158 | ** -------------------------------------------------------------- */ |
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| 159 | { |
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| 160 | pairs_t* pairs = mxMalloc(sizeof(pairs_t)*M) ; |
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| 161 | int e, i, j ; |
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| 162 | double c = 0 ; |
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| 163 | double* RESiterator = RESpt ; |
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| 164 | double* Xiterator = Xpt ; |
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| 165 | double* Witerator = Wpt ; |
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| 166 | |
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| 167 | for(j = 0 ; j < N ; ++j) { |
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| 168 | e = 0; |
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| 169 | |
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| 170 | for(i = 0 ; i < M ; ++i) { |
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| 171 | pairs[i].x = *Xiterator++ ; |
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| 172 | pairs[i].w = *Witerator++ ; |
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| 173 | } |
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| 174 | |
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| 175 | qsort(pairs, M, sizeof(pairs_t), cmp_pairs) ; |
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| 176 | |
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| 177 | /* Head */ |
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| 178 | for(i = 0 ; pairs[i].x < EDGESpt[e] ; ++i) ; |
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| 179 | |
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| 180 | /* Body */ |
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| 181 | while(i < M) { |
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| 182 | c = 0 ; |
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| 183 | e += 1 ; |
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| 184 | if(e == NE) break ; |
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| 185 | |
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| 186 | for( ; pairs[i].x < EDGESpt[e] && i < M ; ++i) |
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| 187 | c += pairs[i].w ; |
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| 188 | |
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| 189 | RESiterator[e-1] = c ; |
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| 190 | } |
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| 191 | |
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| 192 | /* Tail */ |
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| 193 | c = 0 ; |
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| 194 | for( ; pairs[i].x == EDGESpt[NE-1] && i < M ; ++i) |
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| 195 | c += pairs[i].w ; |
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| 196 | RESiterator[NE-1] = c ; |
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| 197 | |
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| 198 | /* Next column */ |
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| 199 | RESiterator += NE ; |
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| 200 | } |
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| 201 | |
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| 202 | mxFree(pairs) ; |
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| 203 | } |
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| 204 | return ; |
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| 205 | } |
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| 206 | |
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| 207 | |
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