553 lines
24 KiB
PHP
Executable File
553 lines
24 KiB
PHP
Executable File
<?php
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/**
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* Zend Framework
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*
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* LICENSE
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*
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* This source file is subject to the new BSD license that is bundled
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* with this package in the file LICENSE.txt.
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* It is also available through the world-wide-web at this URL:
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* http://framework.zend.com/license/new-bsd
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* If you did not receive a copy of the license and are unable to
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* obtain it through the world-wide-web, please send an email
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* to license@zend.com so we can send you a copy immediately.
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*
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* @category Zend
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* @package Zend_Search_Lucene
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* @subpackage Search
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* @copyright Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)
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* @license http://framework.zend.com/license/new-bsd New BSD License
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* @version $Id: Similarity.php 20096 2010-01-06 02:05:09Z bkarwin $
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*/
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/**
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* @category Zend
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* @package Zend_Search_Lucene
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* @subpackage Search
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* @copyright Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)
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* @license http://framework.zend.com/license/new-bsd New BSD License
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*/
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abstract class Zend_Search_Lucene_Search_Similarity
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{
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/**
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* The Similarity implementation used by default.
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*
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* @var Zend_Search_Lucene_Search_Similarity
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*/
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private static $_defaultImpl;
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/**
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* Cache of decoded bytes.
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* Array of floats
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*
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* @var array
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*/
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private static $_normTable = array( 0 => 0.0,
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1 => 5.820766E-10,
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2 => 6.9849193E-10,
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3 => 8.1490725E-10,
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4 => 9.313226E-10,
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5 => 1.1641532E-9,
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6 => 1.3969839E-9,
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7 => 1.6298145E-9,
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8 => 1.8626451E-9,
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9 => 2.3283064E-9,
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10 => 2.7939677E-9,
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11 => 3.259629E-9,
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12 => 3.7252903E-9,
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13 => 4.656613E-9,
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14 => 5.5879354E-9,
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15 => 6.519258E-9,
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16 => 7.4505806E-9,
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17 => 9.313226E-9,
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18 => 1.1175871E-8,
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19 => 1.3038516E-8,
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20 => 1.4901161E-8,
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21 => 1.8626451E-8,
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22 => 2.2351742E-8,
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23 => 2.6077032E-8,
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24 => 2.9802322E-8,
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25 => 3.7252903E-8,
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26 => 4.4703484E-8,
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27 => 5.2154064E-8,
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28 => 5.9604645E-8,
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29 => 7.4505806E-8,
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30 => 8.940697E-8,
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31 => 1.0430813E-7,
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32 => 1.1920929E-7,
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33 => 1.4901161E-7,
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34 => 1.7881393E-7,
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35 => 2.0861626E-7,
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36 => 2.3841858E-7,
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37 => 2.9802322E-7,
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38 => 3.5762787E-7,
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39 => 4.172325E-7,
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40 => 4.7683716E-7,
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41 => 5.9604645E-7,
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42 => 7.1525574E-7,
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43 => 8.34465E-7,
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44 => 9.536743E-7,
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45 => 1.1920929E-6,
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46 => 1.4305115E-6,
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47 => 1.66893E-6,
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48 => 1.9073486E-6,
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49 => 2.3841858E-6,
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50 => 2.861023E-6,
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51 => 3.33786E-6,
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52 => 3.8146973E-6,
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53 => 4.7683716E-6,
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54 => 5.722046E-6,
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55 => 6.67572E-6,
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56 => 7.6293945E-6,
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57 => 9.536743E-6,
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58 => 1.1444092E-5,
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59 => 1.335144E-5,
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60 => 1.5258789E-5,
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61 => 1.9073486E-5,
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62 => 2.2888184E-5,
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63 => 2.670288E-5,
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64 => 3.0517578E-5,
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65 => 3.8146973E-5,
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66 => 4.5776367E-5,
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67 => 5.340576E-5,
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68 => 6.1035156E-5,
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69 => 7.6293945E-5,
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70 => 9.1552734E-5,
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71 => 1.0681152E-4,
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72 => 1.2207031E-4,
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73 => 1.5258789E-4,
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74 => 1.8310547E-4,
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75 => 2.1362305E-4,
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76 => 2.4414062E-4,
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77 => 3.0517578E-4,
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78 => 3.6621094E-4,
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79 => 4.272461E-4,
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80 => 4.8828125E-4,
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81 => 6.1035156E-4,
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82 => 7.324219E-4,
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83 => 8.544922E-4,
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84 => 9.765625E-4,
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85 => 0.0012207031,
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86 => 0.0014648438,
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87 => 0.0017089844,
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88 => 0.001953125,
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89 => 0.0024414062,
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90 => 0.0029296875,
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91 => 0.0034179688,
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92 => 0.00390625,
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93 => 0.0048828125,
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94 => 0.005859375,
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95 => 0.0068359375,
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96 => 0.0078125,
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97 => 0.009765625,
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98 => 0.01171875,
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99 => 0.013671875,
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100 => 0.015625,
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101 => 0.01953125,
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102 => 0.0234375,
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103 => 0.02734375,
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104 => 0.03125,
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105 => 0.0390625,
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106 => 0.046875,
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107 => 0.0546875,
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108 => 0.0625,
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109 => 0.078125,
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110 => 0.09375,
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111 => 0.109375,
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112 => 0.125,
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113 => 0.15625,
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114 => 0.1875,
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115 => 0.21875,
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116 => 0.25,
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117 => 0.3125,
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118 => 0.375,
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119 => 0.4375,
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120 => 0.5,
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121 => 0.625,
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122 => 0.75,
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123 => 0.875,
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124 => 1.0,
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125 => 1.25,
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126 => 1.5,
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127 => 1.75,
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128 => 2.0,
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129 => 2.5,
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130 => 3.0,
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131 => 3.5,
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132 => 4.0,
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133 => 5.0,
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134 => 6.0,
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135 => 7.0,
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136 => 8.0,
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137 => 10.0,
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138 => 12.0,
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139 => 14.0,
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140 => 16.0,
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141 => 20.0,
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142 => 24.0,
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143 => 28.0,
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144 => 32.0,
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145 => 40.0,
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146 => 48.0,
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147 => 56.0,
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148 => 64.0,
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149 => 80.0,
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150 => 96.0,
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151 => 112.0,
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152 => 128.0,
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153 => 160.0,
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154 => 192.0,
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155 => 224.0,
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156 => 256.0,
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157 => 320.0,
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158 => 384.0,
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159 => 448.0,
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160 => 512.0,
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161 => 640.0,
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162 => 768.0,
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163 => 896.0,
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164 => 1024.0,
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165 => 1280.0,
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166 => 1536.0,
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167 => 1792.0,
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168 => 2048.0,
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169 => 2560.0,
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170 => 3072.0,
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171 => 3584.0,
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172 => 4096.0,
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173 => 5120.0,
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174 => 6144.0,
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175 => 7168.0,
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176 => 8192.0,
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177 => 10240.0,
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178 => 12288.0,
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179 => 14336.0,
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180 => 16384.0,
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181 => 20480.0,
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182 => 24576.0,
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183 => 28672.0,
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184 => 32768.0,
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185 => 40960.0,
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186 => 49152.0,
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187 => 57344.0,
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188 => 65536.0,
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189 => 81920.0,
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190 => 98304.0,
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191 => 114688.0,
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192 => 131072.0,
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193 => 163840.0,
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194 => 196608.0,
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195 => 229376.0,
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196 => 262144.0,
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197 => 327680.0,
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198 => 393216.0,
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199 => 458752.0,
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200 => 524288.0,
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201 => 655360.0,
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202 => 786432.0,
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203 => 917504.0,
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204 => 1048576.0,
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205 => 1310720.0,
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206 => 1572864.0,
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207 => 1835008.0,
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208 => 2097152.0,
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209 => 2621440.0,
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210 => 3145728.0,
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211 => 3670016.0,
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212 => 4194304.0,
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213 => 5242880.0,
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214 => 6291456.0,
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215 => 7340032.0,
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216 => 8388608.0,
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217 => 1.048576E7,
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218 => 1.2582912E7,
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219 => 1.4680064E7,
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220 => 1.6777216E7,
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221 => 2.097152E7,
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222 => 2.5165824E7,
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223 => 2.9360128E7,
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224 => 3.3554432E7,
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225 => 4.194304E7,
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226 => 5.0331648E7,
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227 => 5.8720256E7,
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228 => 6.7108864E7,
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229 => 8.388608E7,
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230 => 1.00663296E8,
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231 => 1.17440512E8,
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232 => 1.34217728E8,
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233 => 1.6777216E8,
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234 => 2.01326592E8,
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235 => 2.34881024E8,
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236 => 2.68435456E8,
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237 => 3.3554432E8,
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238 => 4.02653184E8,
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239 => 4.69762048E8,
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240 => 5.3687091E8,
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241 => 6.7108864E8,
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242 => 8.0530637E8,
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243 => 9.395241E8,
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244 => 1.07374182E9,
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245 => 1.34217728E9,
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246 => 1.61061274E9,
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247 => 1.87904819E9,
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248 => 2.14748365E9,
|
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249 => 2.68435456E9,
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250 => 3.22122547E9,
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251 => 3.75809638E9,
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252 => 4.2949673E9,
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253 => 5.3687091E9,
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254 => 6.4424509E9,
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255 => 7.5161928E9 );
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/**
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* Set the default Similarity implementation used by indexing and search
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* code.
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*
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* @param Zend_Search_Lucene_Search_Similarity $similarity
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*/
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public static function setDefault(Zend_Search_Lucene_Search_Similarity $similarity)
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{
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self::$_defaultImpl = $similarity;
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}
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/**
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* Return the default Similarity implementation used by indexing and search
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* code.
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*
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* @return Zend_Search_Lucene_Search_Similarity
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*/
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public static function getDefault()
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{
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if (!self::$_defaultImpl instanceof Zend_Search_Lucene_Search_Similarity) {
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include_once 'Zend/Search/Lucene/Search/Similarity/Default.php';
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self::$_defaultImpl = new Zend_Search_Lucene_Search_Similarity_Default();
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}
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return self::$_defaultImpl;
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}
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/**
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* Computes the normalization value for a field given the total number of
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* terms contained in a field. These values, together with field boosts, are
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* stored in an index and multipled into scores for hits on each field by the
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* search code.
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*
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* Matches in longer fields are less precise, so implemenations of this
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* method usually return smaller values when 'numTokens' is large,
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* and larger values when 'numTokens' is small.
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*
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* That these values are computed under
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* IndexWriter::addDocument(Document) and stored then using
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* encodeNorm(float). Thus they have limited precision, and documents
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* must be re-indexed if this method is altered.
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*
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* fieldName - name of field
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* numTokens - the total number of tokens contained in fields named
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* 'fieldName' of 'doc'.
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* Returns a normalization factor for hits on this field of this document
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*
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* @param string $fieldName
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* @param integer $numTokens
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* @return float
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*/
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abstract public function lengthNorm($fieldName, $numTokens);
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/**
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* Computes the normalization value for a query given the sum of the squared
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* weights of each of the query terms. This value is then multipled into the
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* weight of each query term.
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*
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* This does not affect ranking, but rather just attempts to make scores
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* from different queries comparable.
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*
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* sumOfSquaredWeights - the sum of the squares of query term weights
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* Returns a normalization factor for query weights
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*
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* @param float $sumOfSquaredWeights
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* @return float
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*/
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abstract public function queryNorm($sumOfSquaredWeights);
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/**
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* Decodes a normalization factor stored in an index.
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*
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* @param integer $byte
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* @return float
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*/
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public static function decodeNorm($byte)
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{
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return self::$_normTable[$byte & 0xFF];
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}
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/**
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* Encodes a normalization factor for storage in an index.
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*
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* The encoding uses a five-bit exponent and three-bit mantissa, thus
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* representing values from around 7x10^9 to 2x10^-9 with about one
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* significant decimal digit of accuracy. Zero is also represented.
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* Negative numbers are rounded up to zero. Values too large to represent
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* are rounded down to the largest representable value. Positive values too
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* small to represent are rounded up to the smallest positive representable
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* value.
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*
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* @param float $f
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* @return integer
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*/
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static function encodeNorm($f)
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{
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return self::_floatToByte($f);
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}
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/**
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* Float to byte conversion
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*
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* @param integer $b
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* @return float
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*/
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private static function _floatToByte($f)
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{
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// round negatives up to zero
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if ($f <= 0.0) {
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return 0;
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}
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// search for appropriate value
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$lowIndex = 0;
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$highIndex = 255;
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while ($highIndex >= $lowIndex) {
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// $mid = ($highIndex - $lowIndex)/2;
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$mid = ($highIndex + $lowIndex) >> 1;
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$delta = $f - self::$_normTable[$mid];
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if ($delta < 0) {
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$highIndex = $mid-1;
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} elseif ($delta > 0) {
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$lowIndex = $mid+1;
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} else {
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return $mid; // We got it!
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}
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}
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// round to closest value
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if ($highIndex != 255
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&& $f - self::$_normTable[$highIndex] > self::$_normTable[$highIndex+1] - $f
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) {
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return $highIndex + 1;
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} else {
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return $highIndex;
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}
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}
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/**
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* Computes a score factor based on a term or phrase's frequency in a
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* document. This value is multiplied by the idf(Term, Searcher)
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* factor for each term in the query and these products are then summed to
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* form the initial score for a document.
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*
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* Terms and phrases repeated in a document indicate the topic of the
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* document, so implementations of this method usually return larger values
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* when 'freq' is large, and smaller values when 'freq'
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* is small.
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*
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* freq - the frequency of a term within a document
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* Returns a score factor based on a term's within-document frequency
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*
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* @param float $freq
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* @return float
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*/
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abstract public function tf($freq);
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/**
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* Computes the amount of a sloppy phrase match, based on an edit distance.
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* This value is summed for each sloppy phrase match in a document to form
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* the frequency that is passed to tf(float).
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*
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* A phrase match with a small edit distance to a document passage more
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* closely matches the document, so implementations of this method usually
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* return larger values when the edit distance is small and smaller values
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* when it is large.
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*
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* distance - the edit distance of this sloppy phrase match
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* Returns the frequency increment for this match
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*
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* @param integer $distance
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* @return float
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*/
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abstract public function sloppyFreq($distance);
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/**
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* Computes a score factor for a simple term or a phrase.
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*
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* The default implementation is:
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* return idfFreq(searcher.docFreq(term), searcher.maxDoc());
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*
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* input - the term in question or array of terms
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* reader - reader the document collection being searched
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* Returns a score factor for the term
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*
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* @param mixed $input
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* @param Zend_Search_Lucene_Interface $reader
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* @return a score factor for the term
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*/
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public function idf($input, Zend_Search_Lucene_Interface $reader)
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{
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if (!is_array($input)) {
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return $this->idfFreq($reader->docFreq($input), $reader->count());
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} else {
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$idf = 0.0;
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foreach ($input as $term) {
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$idf += $this->idfFreq($reader->docFreq($term), $reader->count());
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}
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return $idf;
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}
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}
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|
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/**
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* Computes a score factor based on a term's document frequency (the number
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* of documents which contain the term). This value is multiplied by the
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* tf(int) factor for each term in the query and these products are
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* then summed to form the initial score for a document.
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*
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* Terms that occur in fewer documents are better indicators of topic, so
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* implemenations of this method usually return larger values for rare terms,
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* and smaller values for common terms.
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*
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* docFreq - the number of documents which contain the term
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* numDocs - the total number of documents in the collection
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* Returns a score factor based on the term's document frequency
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*
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* @param integer $docFreq
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* @param integer $numDocs
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* @return float
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*/
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abstract public function idfFreq($docFreq, $numDocs);
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/**
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* Computes a score factor based on the fraction of all query terms that a
|
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* document contains. This value is multiplied into scores.
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*
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|
* The presence of a large portion of the query terms indicates a better
|
|
* match with the query, so implemenations of this method usually return
|
|
* larger values when the ratio between these parameters is large and smaller
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|
* values when the ratio between them is small.
|
|
*
|
|
* overlap - the number of query terms matched in the document
|
|
* maxOverlap - the total number of terms in the query
|
|
* Returns a score factor based on term overlap with the query
|
|
*
|
|
* @param integer $overlap
|
|
* @param integer $maxOverlap
|
|
* @return float
|
|
*/
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|
abstract public function coord($overlap, $maxOverlap);
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|
}
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|