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4349 | Serge | 1 | /* |
2 | * linear least squares model |
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3 | * |
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4 | * Copyright (c) 2006 Michael Niedermayer |
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5 | * |
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6 | * This file is part of FFmpeg. |
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7 | * |
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8 | * FFmpeg is free software; you can redistribute it and/or |
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9 | * modify it under the terms of the GNU Lesser General Public |
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10 | * License as published by the Free Software Foundation; either |
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11 | * version 2.1 of the License, or (at your option) any later version. |
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12 | * |
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13 | * FFmpeg is distributed in the hope that it will be useful, |
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14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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16 | * Lesser General Public License for more details. |
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17 | * |
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18 | * You should have received a copy of the GNU Lesser General Public |
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19 | * License along with FFmpeg; if not, write to the Free Software |
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20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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21 | */ |
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22 | |||
23 | /** |
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24 | * @file |
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25 | * linear least squares model |
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26 | */ |
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27 | |||
28 | #include |
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29 | #include |
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30 | |||
31 | #include "attributes.h" |
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32 | #include "version.h" |
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33 | #include "lls1.h" |
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34 | |||
35 | #if FF_API_LLS1 |
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36 | |||
37 | av_cold void avpriv_init_lls(LLSModel *m, int indep_count) |
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38 | { |
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39 | memset(m, 0, sizeof(LLSModel)); |
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40 | m->indep_count = indep_count; |
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41 | } |
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42 | |||
43 | void avpriv_update_lls(LLSModel *m, double *var, double decay) |
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44 | { |
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45 | int i, j; |
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46 | |||
47 | for (i = 0; i <= m->indep_count; i++) { |
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48 | for (j = i; j <= m->indep_count; j++) { |
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49 | m->covariance[i][j] *= decay; |
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50 | m->covariance[i][j] += var[i] * var[j]; |
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51 | } |
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52 | } |
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53 | } |
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54 | |||
55 | void avpriv_solve_lls(LLSModel *m, double threshold, unsigned short min_order) |
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56 | { |
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57 | int i, j, k; |
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58 | double (*factor)[MAX_VARS + 1] = (void *) &m->covariance[1][0]; |
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59 | double (*covar) [MAX_VARS + 1] = (void *) &m->covariance[1][1]; |
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60 | double *covar_y = m->covariance[0]; |
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61 | int count = m->indep_count; |
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62 | |||
63 | for (i = 0; i < count; i++) { |
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64 | for (j = i; j < count; j++) { |
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65 | double sum = covar[i][j]; |
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66 | |||
67 | for (k = i - 1; k >= 0; k--) |
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68 | sum -= factor[i][k] * factor[j][k]; |
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69 | |||
70 | if (i == j) { |
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71 | if (sum < threshold) |
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72 | sum = 1.0; |
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73 | factor[i][i] = sqrt(sum); |
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74 | } else { |
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75 | factor[j][i] = sum / factor[i][i]; |
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76 | } |
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77 | } |
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78 | } |
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79 | |||
80 | for (i = 0; i < count; i++) { |
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81 | double sum = covar_y[i + 1]; |
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82 | |||
83 | for (k = i - 1; k >= 0; k--) |
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84 | sum -= factor[i][k] * m->coeff[0][k]; |
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85 | |||
86 | m->coeff[0][i] = sum / factor[i][i]; |
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87 | } |
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88 | |||
89 | for (j = count - 1; j >= min_order; j--) { |
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90 | for (i = j; i >= 0; i--) { |
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91 | double sum = m->coeff[0][i]; |
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92 | |||
93 | for (k = i + 1; k <= j; k++) |
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94 | sum -= factor[k][i] * m->coeff[j][k]; |
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95 | |||
96 | m->coeff[j][i] = sum / factor[i][i]; |
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97 | } |
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98 | |||
99 | m->variance[j] = covar_y[0]; |
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100 | |||
101 | for (i = 0; i <= j; i++) { |
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102 | double sum = m->coeff[j][i] * covar[i][i] - 2 * covar_y[i + 1]; |
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103 | |||
104 | for (k = 0; k < i; k++) |
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105 | sum += 2 * m->coeff[j][k] * covar[k][i]; |
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106 | |||
107 | m->variance[j] += m->coeff[j][i] * sum; |
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108 | } |
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109 | } |
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110 | } |
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111 | |||
112 | double avpriv_evaluate_lls(LLSModel *m, double *param, int order) |
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113 | { |
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114 | int i; |
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115 | double out = 0; |
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116 | |||
117 | for (i = 0; i <= order; i++) |
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118 | out += param[i] * m->coeff[order][i]; |
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119 | |||
120 | return out; |
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121 | } |
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122 | |||
123 | #if FF_API_LLS_PRIVATE |
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124 | av_cold void av_init_lls(LLSModel *m, int indep_count) |
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125 | { |
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126 | avpriv_init_lls(m, indep_count); |
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127 | } |
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128 | void av_update_lls(LLSModel *m, double *param, double decay) |
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129 | { |
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130 | avpriv_update_lls(m, param, decay); |
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131 | } |
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132 | void av_solve_lls(LLSModel *m, double threshold, int min_order) |
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133 | { |
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134 | avpriv_solve_lls(m, threshold, min_order); |
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135 | } |
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136 | double av_evaluate_lls(LLSModel *m, double *param, int order) |
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137 | { |
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138 | return avpriv_evaluate_lls(m, param, order); |
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139 | } |
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140 | #endif /* FF_API_LLS_PRIVATE */ |
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141 | |||
142 | #endif /* FF_API_LLS1 */ |
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143 | |||
144 | #ifdef TEST |
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145 | |||
146 | #include |
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147 | #include |
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148 | #include "lfg.h" |
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149 | |||
150 | int main(void) |
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151 | { |
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152 | LLSModel m; |
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153 | int i, order; |
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154 | AVLFG lfg; |
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155 | |||
156 | av_lfg_init(&lfg, 1); |
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157 | avpriv_init_lls(&m, 3); |
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158 | |||
159 | for (i = 0; i < 100; i++) { |
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160 | double var[4]; |
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161 | double eval; |
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162 | |||
163 | var[0] = (av_lfg_get(&lfg) / (double) UINT_MAX - 0.5) * 2; |
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164 | var[1] = var[0] + av_lfg_get(&lfg) / (double) UINT_MAX - 0.5; |
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165 | var[2] = var[1] + av_lfg_get(&lfg) / (double) UINT_MAX - 0.5; |
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166 | var[3] = var[2] + av_lfg_get(&lfg) / (double) UINT_MAX - 0.5; |
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167 | avpriv_update_lls(&m, var, 0.99); |
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168 | avpriv_solve_lls(&m, 0.001, 0); |
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169 | for (order = 0; order < 3; order++) { |
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170 | eval = avpriv_evaluate_lls(&m, var + 1, order); |
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171 | printf("real:%9f order:%d pred:%9f var:%f coeffs:%f %9f %9f\n", |
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172 | var[0], order, eval, sqrt(m.variance[order] / (i + 1)), |
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173 | m.coeff[order][0], m.coeff[order][1], |
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174 | m.coeff[order][2]); |
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175 | } |
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176 | } |
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177 | return 0; |
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178 | } |
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179 | |||
180 | #endif>>=>>=>=>>>>>=>=> |