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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