corrade-vassal – Blame information for rev 1
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1 | vero | 1 | /* |
2 | * CVS identifier: |
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3 | * |
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4 | * $Id: MathUtil.java,v 1.15 2001/09/14 08:48:51 grosbois Exp $ |
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5 | * |
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6 | * Class: MathUtil |
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7 | * |
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8 | * Description: Utility mathematical methods |
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9 | * |
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10 | * |
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11 | * |
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12 | * COPYRIGHT: |
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13 | * |
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14 | * This software module was originally developed by Raphaël Grosbois and |
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15 | * Diego Santa Cruz (Swiss Federal Institute of Technology-EPFL); Joel |
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16 | * Askelöf (Ericsson Radio Systems AB); and Bertrand Berthelot, David |
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17 | * Bouchard, Félix Henry, Gerard Mozelle and Patrice Onno (Canon Research |
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18 | * Centre France S.A) in the course of development of the JPEG2000 |
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19 | * standard as specified by ISO/IEC 15444 (JPEG 2000 Standard). This |
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20 | * software module is an implementation of a part of the JPEG 2000 |
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21 | * Standard. Swiss Federal Institute of Technology-EPFL, Ericsson Radio |
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22 | * Systems AB and Canon Research Centre France S.A (collectively JJ2000 |
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23 | * Partners) agree not to assert against ISO/IEC and users of the JPEG |
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24 | * 2000 Standard (Users) any of their rights under the copyright, not |
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25 | * including other intellectual property rights, for this software module |
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26 | * with respect to the usage by ISO/IEC and Users of this software module |
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27 | * or modifications thereof for use in hardware or software products |
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28 | * claiming conformance to the JPEG 2000 Standard. Those intending to use |
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29 | * this software module in hardware or software products are advised that |
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30 | * their use may infringe existing patents. The original developers of |
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31 | * this software module, JJ2000 Partners and ISO/IEC assume no liability |
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32 | * for use of this software module or modifications thereof. No license |
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33 | * or right to this software module is granted for non JPEG 2000 Standard |
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34 | * conforming products. JJ2000 Partners have full right to use this |
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35 | * software module for his/her own purpose, assign or donate this |
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36 | * software module to any third party and to inhibit third parties from |
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37 | * using this software module for non JPEG 2000 Standard conforming |
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38 | * products. This copyright notice must be included in all copies or |
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39 | * derivative works of this software module. |
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40 | * |
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41 | * Copyright (c) 1999/2000 JJ2000 Partners. |
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42 | * */ |
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43 | using System; |
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44 | namespace CSJ2K.j2k.util |
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45 | { |
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46 | |||
47 | /// <summary> This class contains a collection of utility methods fro mathematical |
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48 | /// operations. All methods are static. |
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49 | /// |
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50 | /// </summary> |
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51 | public class MathUtil |
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52 | { |
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53 | |||
54 | /// <summary> Method that calculates the floor of the log, base 2, of 'x'. The |
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55 | /// calculation is performed in integer arithmetic, therefore, it is exact. |
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56 | /// |
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57 | /// </summary> |
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58 | /// <param name="x">The value to calculate log2 on. |
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59 | /// |
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60 | /// </param> |
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61 | /// <returns> floor(log(x)/log(2)), calculated in an exact way. |
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62 | /// |
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63 | /// </returns> |
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64 | public static int log2(int x) |
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65 | { |
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66 | int y, v; |
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67 | // No log of 0 or negative |
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68 | if (x <= 0) |
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69 | { |
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70 | throw new System.ArgumentException("" + x + " <= 0"); |
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71 | } |
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72 | // Calculate log2 (it's actually floor log2) |
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73 | v = x; |
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74 | y = - 1; |
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75 | while (v > 0) |
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76 | { |
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77 | v >>= 1; |
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78 | y++; |
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79 | } |
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80 | return y; |
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81 | } |
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82 | |||
83 | /// <summary> Method that calculates the Least Common Multiple (LCM) of two strictly |
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84 | /// positive integer numbers. |
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85 | /// |
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86 | /// </summary> |
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87 | /// <param name="x1">First number |
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88 | /// |
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89 | /// </param> |
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90 | /// <param name="x2">Second number |
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91 | /// |
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92 | /// </param> |
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93 | public static int lcm(int x1, int x2) |
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94 | { |
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95 | if (x1 <= 0 || x2 <= 0) |
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96 | { |
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97 | throw new System.ArgumentException("Cannot compute the least " + "common multiple of two " + "numbers if one, at least," + "is negative."); |
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98 | } |
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99 | int max, min; |
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100 | if (x1 > x2) |
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101 | { |
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102 | max = x1; |
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103 | min = x2; |
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104 | } |
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105 | else |
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106 | { |
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107 | max = x2; |
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108 | min = x1; |
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109 | } |
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110 | for (int i = 1; i <= min; i++) |
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111 | { |
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112 | if ((max * i) % min == 0) |
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113 | { |
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114 | return i * max; |
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115 | } |
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116 | } |
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117 | throw new System.ApplicationException("Cannot find the least common multiple of numbers " + x1 + " and " + x2); |
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118 | } |
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119 | |||
120 | /// <summary> Method that calculates the Least Common Multiple (LCM) of several |
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121 | /// positive integer numbers. |
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122 | /// |
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123 | /// </summary> |
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124 | /// <param name="x">Array containing the numbers. |
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125 | /// |
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126 | /// </param> |
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127 | public static int lcm(int[] x) |
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128 | { |
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129 | if (x.Length < 2) |
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130 | { |
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131 | throw new System.ApplicationException("Do not use this method if there are less than" + " two numbers."); |
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132 | } |
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133 | int tmp = lcm(x[x.Length - 1], x[x.Length - 2]); |
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134 | for (int i = x.Length - 3; i >= 0; i--) |
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135 | { |
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136 | if (x[i] <= 0) |
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137 | { |
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138 | throw new System.ArgumentException("Cannot compute the least " + "common multiple of " + "several numbers where " + "one, at least," + "is negative."); |
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139 | } |
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140 | tmp = lcm(tmp, x[i]); |
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141 | } |
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142 | return tmp; |
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143 | } |
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144 | |||
145 | /// <summary> Method that calculates the Greatest Common Divisor (GCD) of two |
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146 | /// positive integer numbers. |
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147 | /// |
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148 | /// </summary> |
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149 | public static int gcd(int x1, int x2) |
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150 | { |
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151 | if (x1 < 0 || x2 < 0) |
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152 | { |
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153 | throw new System.ArgumentException("Cannot compute the GCD " + "if one integer is negative."); |
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154 | } |
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155 | int a, b, g, z; |
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156 | |||
157 | if (x1 > x2) |
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158 | { |
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159 | a = x1; |
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160 | b = x2; |
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161 | } |
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162 | else |
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163 | { |
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164 | a = x2; |
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165 | b = x1; |
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166 | } |
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167 | |||
168 | if (b == 0) |
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169 | return 0; |
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170 | |||
171 | g = b; |
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172 | |||
173 | while (g != 0) |
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174 | { |
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175 | z = a % g; |
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176 | a = g; |
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177 | g = z; |
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178 | } |
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179 | return a; |
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180 | } |
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181 | |||
182 | /// <summary> Method that calculates the Greatest Common Divisor (GCD) of several |
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183 | /// positive integer numbers. |
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184 | /// |
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185 | /// </summary> |
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186 | /// <param name="x">Array containing the numbers. |
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187 | /// |
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188 | /// </param> |
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189 | public static int gcd(int[] x) |
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190 | { |
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191 | if (x.Length < 2) |
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192 | { |
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193 | throw new System.ApplicationException("Do not use this method if there are less than" + " two numbers."); |
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194 | } |
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195 | int tmp = gcd(x[x.Length - 1], x[x.Length - 2]); |
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196 | for (int i = x.Length - 3; i >= 0; i--) |
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197 | { |
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198 | if (x[i] < 0) |
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199 | { |
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200 | throw new System.ArgumentException("Cannot compute the least " + "common multiple of " + "several numbers where " + "one, at least," + "is negative."); |
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201 | } |
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202 | tmp = gcd(tmp, x[i]); |
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203 | } |
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204 | return tmp; |
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205 | } |
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206 | } |
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207 | } |