| 0 | 1 <html> | 
|  | 2 <head> | 
|  | 3 <title>MayaChemTools:Code:MathUtil.pm</title> | 
|  | 4 <meta http-equiv="content-type" content="text/html;charset=utf-8"> | 
|  | 5 <link rel="stylesheet" type="text/css" href="../../../css/MayaChemToolsCode.css"> | 
|  | 6 </head> | 
|  | 7 <body leftmargin="20" rightmargin="20" topmargin="10" bottommargin="10"> | 
|  | 8 <br/> | 
|  | 9 <center> | 
|  | 10 <a href="http://www.mayachemtools.org" title="MayaChemTools Home"><img src="../../../images/MayaChemToolsLogo.gif" border="0" alt="MayaChemTools"></a> | 
|  | 11 </center> | 
|  | 12 <br/> | 
|  | 13 <pre> | 
|  | 14 <a name="package-MathUtil-"></a>   1 <span class="k">package </span><span class="i">MathUtil</span><span class="sc">;</span> | 
|  | 15    2 <span class="c">#</span> | 
|  | 16    3 <span class="c"># $RCSfile: MathUtil.pm,v $</span> | 
|  | 17    4 <span class="c"># $Date: 2015/02/28 20:47:17 $</span> | 
|  | 18    5 <span class="c"># $Revision: 1.28 $</span> | 
|  | 19    6 <span class="c">#</span> | 
|  | 20    7 <span class="c"># Author: Manish Sud <msud@san.rr.com></span> | 
|  | 21    8 <span class="c">#</span> | 
|  | 22    9 <span class="c"># Copyright (C) 2015 Manish Sud. All rights reserved.</span> | 
|  | 23   10 <span class="c">#</span> | 
|  | 24   11 <span class="c"># This file is part of MayaChemTools.</span> | 
|  | 25   12 <span class="c">#</span> | 
|  | 26   13 <span class="c"># MayaChemTools is free software; you can redistribute it and/or modify it under</span> | 
|  | 27   14 <span class="c"># the terms of the GNU Lesser General Public License as published by the Free</span> | 
|  | 28   15 <span class="c"># Software Foundation; either version 3 of the License, or (at your option) any</span> | 
|  | 29   16 <span class="c"># later version.</span> | 
|  | 30   17 <span class="c">#</span> | 
|  | 31   18 <span class="c"># MayaChemTools is distributed in the hope that it will be useful, but without</span> | 
|  | 32   19 <span class="c"># any warranty; without even the implied warranty of merchantability of fitness</span> | 
|  | 33   20 <span class="c"># for a particular purpose.  See the GNU Lesser General Public License for more</span> | 
|  | 34   21 <span class="c"># details.</span> | 
|  | 35   22 <span class="c">#</span> | 
|  | 36   23 <span class="c"># You should have received a copy of the GNU Lesser General Public License</span> | 
|  | 37   24 <span class="c"># along with MayaChemTools; if not, see <http://www.gnu.org/licenses/> or</span> | 
|  | 38   25 <span class="c"># write to the Free Software Foundation Inc., 59 Temple Place, Suite 330,</span> | 
|  | 39   26 <span class="c"># Boston, MA, 02111-1307, USA.</span> | 
|  | 40   27 <span class="c">#</span> | 
|  | 41   28 | 
|  | 42   29 <span class="k">use</span> <span class="w">strict</span><span class="sc">;</span> | 
|  | 43   30 <span class="k">use</span> <span class="w">Exporter</span><span class="sc">;</span> | 
|  | 44   31 <span class="k">use</span> <span class="w">Constants</span><span class="sc">;</span> | 
|  | 45   32 <span class="k">use</span> <span class="w">Math::Trig</span> <span class="s">(</span><span class="s">)</span><span class="sc">;</span> | 
|  | 46   33 <span class="k">use</span> <span class="w">POSIX</span> <span class="s">(</span><span class="s">)</span><span class="sc">;</span> | 
|  | 47   34 | 
|  | 48   35 <span class="k">use</span> <span class="w">vars</span> <span class="q">qw(@ISA @EXPORT @EXPORT_OK %EXPORT_TAGS)</span><span class="sc">;</span> | 
|  | 49   36 | 
|  | 50   37 <span class="i">@ISA</span> = <span class="q">qw(Exporter)</span><span class="sc">;</span> | 
|  | 51   38 <span class="i">@EXPORT</span> = <span class="q">qw(acos asin atan tan ceil floor log10 min max srandom random round GeneratePrimeNumbersUpToLimit GeneratePrimeNumbersUpToCount)</span><span class="sc">;</span> | 
|  | 52   39 <span class="i">@EXPORT_OK</span> = <span class="q">qw()</span><span class="sc">;</span> | 
|  | 53   40 | 
|  | 54   41 <span class="i">%EXPORT_TAGS</span> = <span class="s">(</span><span class="w">all</span>  <span class="cm">=></span> <span class="s">[</span><span class="i">@EXPORT</span><span class="cm">,</span> <span class="i">@EXPORT_OK</span><span class="s">]</span> | 
|  | 55   42                <span class="s">)</span><span class="sc">;</span> | 
|  | 56   43 | 
|  | 57   44 | 
|  | 58   45 <span class="c"># Return next largest integer...</span> | 
|  | 59 <a name="ceil-"></a>  46 <span class="k">sub </span><span class="m">ceil ($)</span> <span class="s">{</span> | 
|  | 60   47   <span class="k">my</span><span class="s">(</span><span class="i">$Value</span><span class="s">)</span> = <span class="i">@_</span><span class="sc">;</span> | 
|  | 61   48 | 
|  | 62   49   <span class="k">return</span> <span class="i">POSIX::ceil</span><span class="s">(</span><span class="i">$Value</span><span class="s">)</span><span class="sc">;</span> | 
|  | 63   50 <span class="s">}</span> | 
|  | 64   51 | 
|  | 65   52 <span class="c"># Return previous smallest integer...</span> | 
|  | 66 <a name="floor-"></a>  53 <span class="k">sub </span><span class="m">floor ($)</span> <span class="s">{</span> | 
|  | 67   54   <span class="k">my</span><span class="s">(</span><span class="i">$Value</span><span class="s">)</span> = <span class="i">@_</span><span class="sc">;</span> | 
|  | 68   55 | 
|  | 69   56   <span class="k">return</span> <span class="i">POSIX::floor</span><span class="s">(</span><span class="i">$Value</span><span class="s">)</span><span class="sc">;</span> | 
|  | 70   57 <span class="s">}</span> | 
|  | 71   58 | 
|  | 72   59 <span class="c"># Calculate log value using base 10...</span> | 
|  | 73 <a name="log10-"></a>  60 <span class="k">sub </span><span class="m">log10 ($)</span> <span class="s">{</span> | 
|  | 74   61   <span class="k">my</span><span class="s">(</span><span class="i">$Value</span><span class="s">)</span> = <span class="i">@_</span><span class="sc">;</span> | 
|  | 75   62 | 
|  | 76   63   <span class="k">return</span> <span class="i">CORE::</span><span class="k">log</span><span class="s">(</span><span class="i">$Value</span><span class="s">)</span>/<span class="i">CORE::</span><span class="k">log</span><span class="s">(</span><span class="n">10</span><span class="s">)</span><span class="sc">;</span> | 
|  | 77   64 <span class="s">}</span> | 
|  | 78   65 | 
|  | 79   66 <span class="c"># Return the smaller of two numbers...</span> | 
|  | 80 <a name="min-"></a>  67 <span class="k">sub </span><span class="m">min ($$)</span> <span class="s">{</span> | 
|  | 81   68   <span class="k">my</span><span class="s">(</span><span class="i">$Value1</span><span class="cm">,</span> <span class="i">$Value2</span><span class="s">)</span> = <span class="i">@_</span><span class="sc">;</span> | 
|  | 82   69 | 
|  | 83   70   <span class="k">return</span> <span class="s">(</span><span class="i">$Value1</span> <= <span class="i">$Value2</span><span class="s">)</span> ? <span class="i">$Value1</span> <span class="co">:</span> <span class="i">$Value2</span><span class="sc">;</span> | 
|  | 84   71 <span class="s">}</span> | 
|  | 85   72 | 
|  | 86   73 <span class="c"># Return the larger of two numbers...</span> | 
|  | 87 <a name="max-"></a>  74 <span class="k">sub </span><span class="m">max ($$)</span> <span class="s">{</span> | 
|  | 88   75   <span class="k">my</span><span class="s">(</span><span class="i">$Value1</span><span class="cm">,</span> <span class="i">$Value2</span><span class="s">)</span> = <span class="i">@_</span><span class="sc">;</span> | 
|  | 89   76 | 
|  | 90   77   <span class="k">return</span> <span class="s">(</span><span class="i">$Value1</span> >= <span class="i">$Value2</span><span class="s">)</span> ? <span class="i">$Value1</span> <span class="co">:</span> <span class="i">$Value2</span><span class="sc">;</span> | 
|  | 91   78 <span class="s">}</span> | 
|  | 92   79 | 
|  | 93   80 <span class="c"># The random number generator implemented in MayaChemTools is a variant of linear</span> | 
|  | 94   81 <span class="c"># congruential generator (LCG) as described by Miller et al. [ Ref 120 ]. It is</span> | 
|  | 95   82 <span class="c"># also referred to as Lehmer random number generator or Park-Miller random number</span> | 
|  | 96   83 <span class="c"># generator.</span> | 
|  | 97   84 <span class="c">#</span> | 
|  | 98   85 <span class="c"># Unlike Perl's core random number generator function rand, the random number</span> | 
|  | 99   86 <span class="c"># generator implemented in MayaChemTools generates consistent random values</span> | 
|  | 100   87 <span class="c"># across different platforms - Windows, CygWin, Linux, Unix - for a specific random</span> | 
|  | 101   88 <span class="c"># seed.</span> | 
|  | 102   89 <span class="c">#</span> | 
|  | 103   90 | 
|  | 104   91 <span class="c"># $RandomModulus = 2**31 - 1;</span> | 
|  | 105   92 <span class="c"># $RandomMultiplier = 16807;</span> | 
|  | 106   93 <span class="c"># $RandomQuotient = $RandomModulus / $RandomMultiplier;</span> | 
|  | 107   94 <span class="c"># $RandomRemainder = $RandomModulus % $RandomMultiplier</span> | 
|  | 108   95 <span class="c">#</span> | 
|  | 109   96 <span class="c"># $MaxRandomSeed = 2*31 -2</span> | 
|  | 110   97 <span class="c">#</span> | 
|  | 111   98 <span class="k">my</span><span class="s">(</span><span class="i">$MaxRandomSeed</span><span class="cm">,</span> <span class="i">$RandomSeed</span><span class="cm">,</span> <span class="i">$RandomModulus</span><span class="cm">,</span> <span class="i">$RandomMultiplier</span><span class="cm">,</span> <span class="i">$RandomQuotient</span><span class="cm">,</span> <span class="i">$RandomRemainder</span><span class="s">)</span><span class="sc">;</span> | 
|  | 112   99 | 
|  | 113  100 <span class="i">$MaxRandomSeed</span> = <span class="n">2147483646</span><span class="sc">;</span> | 
|  | 114  101 <span class="i">$RandomSeed</span> = <span class="n">123456789</span><span class="sc">;</span> | 
|  | 115  102 | 
|  | 116  103 <span class="i">$RandomModulus</span> = <span class="n">2147483647</span><span class="sc">;</span> | 
|  | 117  104 <span class="i">$RandomMultiplier</span> = <span class="n">16807</span><span class="sc">;</span> | 
|  | 118  105 <span class="i">$RandomQuotient</span> = <span class="n">127773</span><span class="sc">;</span> | 
|  | 119  106 <span class="i">$RandomRemainder</span> = <span class="n">2836</span><span class="sc">;</span> | 
|  | 120  107 | 
|  | 121  108 <span class="c"># Set random number seed...</span> | 
|  | 122  109 <span class="c">#</span> | 
|  | 123  110 <span class="c"># The intial value of random number seed is recommeded to be an integer between 1</span> | 
|  | 124  111 <span class="c"># and 2**31 - 2 [Ref 120] which translates to be 1 and 2147483646</span> | 
|  | 125  112 <span class="c">#</span> | 
|  | 126 <a name="srandom-"></a> 113 <span class="k">sub </span><span class="m">srandom ($)</span> <span class="s">{</span> | 
|  | 127  114   <span class="k">my</span><span class="s">(</span><span class="i">$Seed</span><span class="s">)</span> = <span class="i">@_</span><span class="sc">;</span> | 
|  | 128  115 | 
|  | 129  116   <span class="k">if</span> <span class="s">(</span><span class="i">$Seed</span> <= <span class="n">0</span> <span class="s">)</span> <span class="s">{</span> | 
|  | 130  117     <span class="k">die</span> <span class="q">"Error: srandom: Specified seed value must be greater than 0..."</span><span class="sc">;</span> | 
|  | 131  118   <span class="s">}</span> | 
|  | 132  119 | 
|  | 133  120   <span class="i">$RandomSeed</span> = <span class="s">(</span><span class="i">$Seed</span> > <span class="i">$MaxRandomSeed</span><span class="s">)</span> ? <span class="s">(</span><span class="i">$Seed</span> % <span class="i">$MaxRandomSeed</span><span class="s">)</span> <span class="co">:</span> <span class="i">$Seed</span><span class="sc">;</span> | 
|  | 134  121 | 
|  | 135  122   <span class="k">return</span> <span class="i">$RandomSeed</span><span class="sc">;</span> | 
|  | 136  123 <span class="s">}</span> | 
|  | 137  124 | 
|  | 138  125 <span class="c"># Retrun a random number between 0 and less than 1 or specified size...</span> | 
|  | 139  126 <span class="c">#</span> | 
|  | 140 <a name="random-"></a> 127 <span class="k">sub </span><span class="m">random (;$)</span> <span class="s">{</span> | 
|  | 141  128   <span class="k">my</span><span class="s">(</span><span class="i">$Size</span><span class="s">)</span> = <span class="i">@_</span><span class="sc">;</span> | 
|  | 142  129   <span class="k">my</span><span class="s">(</span><span class="i">$Value</span><span class="cm">,</span> <span class="i">$LowValue</span><span class="cm">,</span> <span class="i">$HighValue</span><span class="s">)</span><span class="sc">;</span> | 
|  | 143  130 | 
|  | 144  131   <span class="i">$Size</span> = <span class="k">defined</span> <span class="i">$Size</span> ? <span class="i">$Size</span> <span class="co">:</span> <span class="n">1.0</span><span class="sc">;</span> | 
|  | 145  132 | 
|  | 146  133   <span class="i">$HighValue</span> = <span class="i">$RandomSeed</span> / <span class="i">$RandomQuotient</span><span class="sc">;</span> | 
|  | 147  134   <span class="i">$LowValue</span> = <span class="i">$RandomSeed</span> % <span class="i">$RandomQuotient</span><span class="sc">;</span> | 
|  | 148  135 | 
|  | 149  136   <span class="i">$Value</span> = <span class="i">$RandomMultiplier</span> * <span class="i">$LowValue</span> - <span class="i">$RandomRemainder</span> * <span class="i">$HighValue</span><span class="sc">;</span> | 
|  | 150  137 | 
|  | 151  138   <span class="i">$RandomSeed</span> = <span class="s">(</span><span class="i">$Value</span> > <span class="n">0</span><span class="s">)</span> ? <span class="i">$Value</span> <span class="co">:</span> <span class="s">(</span><span class="i">$Value</span> + <span class="i">$RandomModulus</span><span class="s">)</span><span class="sc">;</span> | 
|  | 152  139 | 
|  | 153  140   <span class="k">return</span> <span class="s">(</span><span class="i">$RandomSeed</span> / <span class="i">$RandomModulus</span><span class="s">)</span> * <span class="i">$Size</span><span class="sc">;</span> | 
|  | 154  141 <span class="s">}</span> | 
|  | 155  142 | 
|  | 156  143 <span class="c"># Round a integer/real number to:</span> | 
|  | 157  144 <span class="c"># . A nearest integer</span> | 
|  | 158  145 <span class="c"># . Specified number of decimal places</span> | 
|  | 159  146 <span class="c">#</span> | 
|  | 160 <a name="round-"></a> 147 <span class="k">sub </span><span class="m">round ($;$)</span> <span class="s">{</span> | 
|  | 161  148   <span class="k">my</span><span class="s">(</span><span class="i">$Value</span><span class="cm">,</span> <span class="i">$DecimalPlaces</span><span class="s">)</span> = <span class="i">@_</span><span class="sc">;</span> | 
|  | 162  149   <span class="k">my</span><span class="s">(</span><span class="i">$RoundedValue</span><span class="s">)</span><span class="sc">;</span> | 
|  | 163  150 | 
|  | 164  151   <span class="k">if</span> <span class="s">(</span><span class="k">defined</span><span class="s">(</span><span class="i">$DecimalPlaces</span><span class="s">)</span> && <span class="i">$DecimalPlaces</span> > <span class="n">0</span><span class="s">)</span> <span class="s">{</span> | 
|  | 165  152     <span class="i">$RoundedValue</span> = <span class="k">sprintf</span> <span class="q">"%.${DecimalPlaces}f"</span><span class="cm">,</span> <span class="i">$Value</span><span class="sc">;</span> | 
|  | 166  153   <span class="s">}</span> | 
|  | 167  154   <span class="k">else</span> <span class="s">{</span> | 
|  | 168  155     <span class="k">if</span> <span class="s">(</span><span class="i">$Value</span> < <span class="n">0</span><span class="s">)</span> <span class="s">{</span> | 
|  | 169  156       <span class="i">$RoundedValue</span> = <span class="k">int</span><span class="s">(</span><span class="i">$Value</span> - <span class="n">0.5</span><span class="s">)</span><span class="sc">;</span> | 
|  | 170  157     <span class="s">}</span> | 
|  | 171  158     <span class="k">else</span> <span class="s">{</span> | 
|  | 172  159       <span class="i">$RoundedValue</span> = <span class="k">int</span><span class="s">(</span><span class="i">$Value</span> + <span class="n">0.5</span><span class="s">)</span><span class="sc">;</span> | 
|  | 173  160     <span class="s">}</span> | 
|  | 174  161   <span class="s">}</span> | 
|  | 175  162   <span class="k">return</span> <span class="i">$RoundedValue</span><span class="sc">;</span> | 
|  | 176  163 <span class="s">}</span> | 
|  | 177  164 | 
|  | 178  165 <span class="c"># Return tangent of an angle expressed in radians.</span> | 
|  | 179 <a name="tan-"></a> 166 <span class="k">sub </span><span class="m">tan</span> <span class="s">{</span> | 
|  | 180  167   <span class="k">my</span><span class="s">(</span><span class="i">$Value</span><span class="s">)</span> = <span class="i">@_</span><span class="sc">;</span> | 
|  | 181  168 | 
|  | 182  169   <span class="k">return</span> <span class="s">(</span><span class="i">CORE::</span><span class="k">sin</span><span class="s">(</span><span class="i">$Value</span><span class="s">)</span>/<span class="i">CORE::</span><span class="k">cos</span><span class="s">(</span><span class="i">$Value</span><span class="s">)</span><span class="s">)</span><span class="sc">;</span> | 
|  | 183  170 <span class="s">}</span> | 
|  | 184  171 | 
|  | 185  172 <span class="c"># Return inverse sine of an angle expressed in radians.</span> | 
|  | 186  173 <span class="c">#</span> | 
|  | 187  174 <span class="c"># For a right angle triangle defined by sides X and Y in a unit circle, Pythagorean theorem implies</span> | 
|  | 188  175 <span class="c"># X**2 + Y**2 = 1 and sin value corresponds to Y. So asin is equivalent to atan2(Y, sqrt(1-Y**2)).</span> | 
|  | 189  176 <span class="c"># However, taking sqrt of negative numbers is problematic; Math::Trig::asin handles it using complex</span> | 
|  | 190  177 <span class="c"># numbers.</span> | 
|  | 191  178 <span class="c">#</span> | 
|  | 192 <a name="asin-"></a> 179 <span class="k">sub </span><span class="m">asin ($)</span> <span class="s">{</span> | 
|  | 193  180   <span class="k">my</span><span class="s">(</span><span class="i">$Value</span><span class="s">)</span> = <span class="i">@_</span><span class="sc">;</span> | 
|  | 194  181 | 
|  | 195  182   <span class="k">return</span> <span class="i">Math::Trig::asin</span><span class="s">(</span><span class="i">$Value</span><span class="s">)</span><span class="sc">;</span> | 
|  | 196  183 <span class="s">}</span> | 
|  | 197  184 | 
|  | 198  185 <span class="c"># Return inverse cosine of an angle expressed in radians.</span> | 
|  | 199  186 <span class="c">#</span> | 
|  | 200  187 <span class="c"># For a right angle triangle defined by sides X and Y in a unit circle, Pythagorean theorem implies</span> | 
|  | 201  188 <span class="c"># X**2 + Y**2 = 1 and cos value corresponds to X. So asin is equivalent to atan2(sqrt(1-X**2), X)</span> | 
|  | 202  189 <span class="c"># However, taking sqrt of negative numbers is problematic; Math::Trig::acos handles it using complex</span> | 
|  | 203  190 <span class="c"># numbers.</span> | 
|  | 204  191 <span class="c">#</span> | 
|  | 205 <a name="acos-"></a> 192 <span class="k">sub </span><span class="m">acos ($)</span> <span class="s">{</span> | 
|  | 206  193   <span class="k">my</span><span class="s">(</span><span class="i">$Value</span><span class="s">)</span> = <span class="i">@_</span><span class="sc">;</span> | 
|  | 207  194 | 
|  | 208  195   <span class="k">return</span> <span class="i">Math::Trig::acos</span><span class="s">(</span><span class="i">$Value</span><span class="s">)</span><span class="sc">;</span> | 
|  | 209  196 <span class="s">}</span> | 
|  | 210  197 | 
|  | 211  198 <span class="c"># Generate prime numbers up to a specified limit and return a reference to an</span> | 
|  | 212  199 <span class="c"># array containing the prime numbers.</span> | 
|  | 213  200 <span class="c">#</span> | 
|  | 214  201 <span class="c"># By default, the first 1000 prime numbers are generated. The 1000th prime</span> | 
|  | 215  202 <span class="c"># number is 7919 and that's why default limit is set to 7920.</span> | 
|  | 216  203 <span class="c">#</span> | 
|  | 217 <a name="GeneratePrimeNumbersUpToLimit-"></a> 204 <span class="k">sub </span><span class="m">GeneratePrimeNumbersUpToLimit (;$)</span> <span class="s">{</span> | 
|  | 218  205   <span class="k">my</span><span class="s">(</span><span class="i">$Limit</span><span class="s">)</span> = <span class="i">@_</span><span class="sc">;</span> | 
|  | 219  206 | 
|  | 220  207   <span class="i">$Limit</span> = <span class="k">defined</span> <span class="i">$Limit</span> ? <span class="i">$Limit</span> <span class="co">:</span> <span class="n">7920</span><span class="sc">;</span> | 
|  | 221  208 | 
|  | 222  209   <span class="k">return</span> <span class="i">_GeneratePrimeNumbers</span><span class="s">(</span><span class="q">'ByLimit'</span><span class="cm">,</span> <span class="i">$Limit</span><span class="s">)</span> | 
|  | 223  210 <span class="s">}</span> | 
|  | 224  211 | 
|  | 225  212 <span class="c"># Generate prime numbers up to specified count of prime numbers and return a</span> | 
|  | 226  213 <span class="c"># reference to an array containing the prime numbers.</span> | 
|  | 227  214 <span class="c">#</span> | 
|  | 228  215 <span class="c"># By default, the first 1000 prime numbers are generated. The 1000th prime</span> | 
|  | 229  216 <span class="c"># number is 7919.</span> | 
|  | 230  217 <span class="c">#</span> | 
|  | 231 <a name="GeneratePrimeNumbersUpToCount-"></a> 218 <span class="k">sub </span><span class="m">GeneratePrimeNumbersUpToCount (;$)</span> <span class="s">{</span> | 
|  | 232  219   <span class="k">my</span><span class="s">(</span><span class="i">$Count</span><span class="s">)</span> = <span class="i">@_</span><span class="sc">;</span> | 
|  | 233  220 | 
|  | 234  221   <span class="i">$Count</span> = <span class="k">defined</span> <span class="i">$Count</span> ? <span class="i">$Count</span> <span class="co">:</span> <span class="n">1000</span><span class="sc">;</span> | 
|  | 235  222 | 
|  | 236  223   <span class="k">return</span> <span class="i">_GeneratePrimeNumbers</span><span class="s">(</span><span class="q">'ByCount'</span><span class="cm">,</span> <span class="i">$Count</span><span class="s">)</span> | 
|  | 237  224 <span class="s">}</span> | 
|  | 238  225 | 
|  | 239  226 <span class="c"># Generate prime numbers up to specified limit or count and return a reference</span> | 
|  | 240  227 <span class="c"># to an array containing the prime numbers.</span> | 
|  | 241  228 <span class="c">#</span> | 
|  | 242  229 <span class="c"># The algorithm to generate prime numbers is a modification of  Sieve of Erastothenes</span> | 
|  | 243  230 <span class="c"># prime number generator.</span> | 
|  | 244  231 <span class="c">#</span> | 
|  | 245 <a name="_GeneratePrimeNumbers-"></a> 232 <span class="k">sub </span><span class="m">_GeneratePrimeNumbers</span> <span class="s">{</span> | 
|  | 246  233   <span class="k">my</span><span class="s">(</span><span class="i">$Mode</span><span class="cm">,</span> <span class="i">$Value</span><span class="s">)</span> = <span class="i">@_</span><span class="sc">;</span> | 
|  | 247  234   <span class="k">my</span><span class="s">(</span><span class="i">$ByLimit</span><span class="cm">,</span> <span class="i">$PrimeNumber</span><span class="cm">,</span> <span class="i">$Number</span><span class="cm">,</span> <span class="i">$SqrtOfNumber</span><span class="cm">,</span> <span class="i">$NumberIsPrime</span><span class="cm">,</span> <span class="i">@PrimeNumbers</span><span class="s">)</span><span class="sc">;</span> | 
|  | 248  235 | 
|  | 249  236   <span class="i">$ByLimit</span> = <span class="s">(</span><span class="i">$Mode</span> =~ <span class="q">/^ByLimit$/i</span><span class="s">)</span> ? <span class="n">1</span> <span class="co">:</span> <span class="n">0</span><span class="sc">;</span> | 
|  | 250  237 | 
|  | 251  238   <span class="i">@PrimeNumbers</span> = <span class="s">(</span><span class="n">2</span><span class="cm">,</span> <span class="n">3</span><span class="s">)</span><span class="sc">;</span> | 
|  | 252  239   <span class="i">$Number</span> = <span class="n">3</span><span class="sc">;</span> | 
|  | 253  240 | 
|  | 254  241   <span class="c"># while ($Number <= $Limit) {</span> | 
|  | 255  242   <span class="k">while</span> <span class="s">(</span><span class="i">$ByLimit</span> ? <span class="s">(</span><span class="i">$Number</span> < <span class="i">$Value</span><span class="s">)</span> <span class="co">:</span> <span class="s">(</span><span class="i">@PrimeNumbers</span> < <span class="i">$Value</span><span class="s">)</span><span class="s">)</span> <span class="s">{</span> | 
|  | 256  243     <span class="i">$Number</span> += <span class="n">2</span><span class="sc">;</span> | 
|  | 257  244     <span class="i">$SqrtOfNumber</span> = <span class="k">sqrt</span> <span class="i">$Number</span><span class="sc">;</span> | 
|  | 258  245 | 
|  | 259  246     <span class="i">$NumberIsPrime</span> = <span class="n">1</span><span class="sc">;</span> | 
|  | 260  247     <span class="j">PRIMENUMBER:</span> <span class="k">for</span> <span class="i">$PrimeNumber</span> <span class="s">(</span><span class="i">@PrimeNumbers</span><span class="s">)</span> <span class="s">{</span> | 
|  | 261  248       <span class="k">if</span> <span class="s">(</span><span class="i">$PrimeNumber</span> > <span class="i">$SqrtOfNumber</span><span class="s">)</span> <span class="s">{</span> | 
|  | 262  249         <span class="k">last</span> <span class="j">PRIMENUMBER</span><span class="sc">;</span> | 
|  | 263  250       <span class="s">}</span> | 
|  | 264  251       <span class="k">if</span> <span class="s">(</span>!<span class="s">(</span><span class="i">$Number</span> % <span class="i">$PrimeNumber</span><span class="s">)</span><span class="s">)</span> <span class="s">{</span> | 
|  | 265  252         <span class="i">$NumberIsPrime</span> = <span class="n">0</span><span class="sc">;</span> | 
|  | 266  253         <span class="k">last</span> <span class="j">PRIMENUMBER</span><span class="sc">;</span> | 
|  | 267  254       <span class="s">}</span> | 
|  | 268  255     <span class="s">}</span> | 
|  | 269  256     <span class="k">if</span> <span class="s">(</span><span class="i">$NumberIsPrime</span><span class="s">)</span> <span class="s">{</span> | 
|  | 270  257       <span class="k">push</span> <span class="i">@PrimeNumbers</span><span class="cm">,</span> <span class="i">$Number</span><span class="sc">;</span> | 
|  | 271  258     <span class="s">}</span> | 
|  | 272  259   <span class="s">}</span> | 
|  | 273  260   <span class="k">return</span> \<span class="i">@PrimeNumbers</span><span class="sc">;</span> | 
|  | 274  261 <span class="s">}</span> | 
|  | 275  262 | 
|  | 276 <a name="EOF-"></a></pre> | 
|  | 277 <p> </p> | 
|  | 278 <br /> | 
|  | 279 <center> | 
|  | 280 <img src="../../../images/h2o2.png"> | 
|  | 281 </center> | 
|  | 282 </body> | 
|  | 283 </html> |