mingw/html/lib/bigrat.html

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  13 <big><strong><span class="block">&nbsp;bigrat - Transparent BigNumber/BigRational support for Perl</span></strong></big>
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  16
  17 <p><a name="__index__"></a></p>
  18 <!-- INDEX BEGIN -->
  19
  20 <ul>
  21
  22         <li><a href="#name">NAME</a></li>
  23         <li><a href="#synopsis">SYNOPSIS</a></li>
  24         <li><a href="#description">DESCRIPTION</a></li>
  25         <ul>
  26
  27                 <li><a href="#modules_used">Modules Used</a></li>
  28                 <li><a href="#math_library">Math Library</a></li>
  29                 <li><a href="#sign">Sign</a></li>
  30                 <li><a href="#methods">Methods</a></li>
  31                 <li><a href="#cavaet">Cavaet</a></li>
  32                 <li><a href="#options">Options</a></li>
  33         </ul>
  34
  35         <li><a href="#examples">EXAMPLES</a></li>
  36         <li><a href="#license">LICENSE</a></li>
  37         <li><a href="#see_also">SEE ALSO</a></li>
  38         <li><a href="#authors">AUTHORS</a></li>
  39 </ul>
  40 <!-- INDEX END -->
  41
  42 <hr />
  43 <p>
  44 </p>
  45 <h1><a name="name">NAME</a></h1>
  46 <p>bigrat - Transparent BigNumber/BigRational support for Perl</p>
  47 <p>
  48 </p>
  49 <hr />
  50 <h1><a name="synopsis">SYNOPSIS</a></h1>
  51 <pre>
  52   use bigrat;</pre>
  53 <pre>
  54   $x = 2 + 4.5,&quot;\n&quot;;                    # BigFloat 6.5
  55   print 1/3 + 1/4,&quot;\n&quot;;                 # produces 7/12</pre>
  56 <p>
  57 </p>
  58 <hr />
  59 <h1><a name="description">DESCRIPTION</a></h1>
  60 <p>All operators (inlcuding basic math operations) are overloaded. Integer and
  61 floating-point constants are created as proper BigInts or BigFloats,
  62 respectively.</p>
  63 <p>Other than <a href="file://C|\msysgit\mingw\html/lib/bignum.html">the bignum manpage</a>, this module upgrades to Math::BigRat, meaning that
  64 instead of 2.5 you will get 2+1/2 as output.</p>
  65 <p>
  66 </p>
  67 <h2><a name="modules_used">Modules Used</a></h2>
  68 <p><code>bigrat</code> is just a thin wrapper around various modules of the Math::BigInt
  69 family. Think of it as the head of the family, who runs the shop, and orders
  70 the others to do the work.</p>
  71 <p>The following modules are currently used by bignum:</p>
  72 <pre>
  73         Math::BigInt::Lite      (for speed, and only if it is loadable)
  74         Math::BigInt
  75         Math::BigFloat
  76         Math::BigRat</pre>
  77 <p>
  78 </p>
  79 <h2><a name="math_library">Math Library</a></h2>
  80 <p>Math with the numbers is done (by default) by a module called
  81 Math::BigInt::Calc. This is equivalent to saying:</p>
  82 <pre>
  83         use bigrat lib =&gt; 'Calc';</pre>
  84 <p>You can change this by using:</p>
  85 <pre>
  86         use bigrat lib =&gt; 'BitVect';</pre>
  87 <p>The following would first try to find Math::BigInt::Foo, then
  88 Math::BigInt::Bar, and when this also fails, revert to Math::BigInt::Calc:</p>
  89 <pre>
  90         use bigrat lib =&gt; 'Foo,Math::BigInt::Bar';</pre>
  91 <p>Please see respective module documentation for further details.</p>
  92 <p>
  93 </p>
  94 <h2><a name="sign">Sign</a></h2>
  95 <p>The sign is either '+', '-', 'NaN', '+inf' or '-inf'.</p>
  96 <p>A sign of 'NaN' is used to represent the result when input arguments are not
  97 numbers or as a result of 0/0. '+inf' and '-inf' represent plus respectively
  98 minus infinity. You will get '+inf' when dividing a positive number by 0, and
  99 '-inf' when dividing any negative number by 0.</p>
 100 <p>
 101 </p>
 102 <h2><a name="methods">Methods</a></h2>
 103 <p>Since all numbers are not objects, you can use all functions that are part of
 104 the BigInt or BigFloat API. It is wise to use only the <code>bxxx()</code> notation, and not
 105 the <code>fxxx()</code> notation, though. This makes you independed on the fact that the
 106 underlying object might morph into a different class than BigFloat.</p>
 107 <p>
 108 </p>
 109 <h2><a name="cavaet">Cavaet</a></h2>
 110 <p>But a warning is in order. When using the following to make a copy of a number,
 111 only a shallow copy will be made.</p>
 112 <pre>
 113         $x = 9; $y = $x;
 114         $x = $y = 7;</pre>
 115 <p>If you want to make a real copy, use the following:</p>
 116 <pre>
 117         $y = $x-&gt;copy();</pre>
 118 <p>Using the copy or the original with overloaded math is okay, e.g. the
 119 following work:</p>
 120 <pre>
 121         $x = 9; $y = $x;
 122         print $x + 1, &quot; &quot;, $y,&quot;\n&quot;;     # prints 10 9</pre>
 123 <p>but calling any method that modifies the number directly will result in
 124 <strong>both</strong> the original and the copy beeing destroyed:</p>
 125 <pre>
 126         $x = 9; $y = $x;
 127         print $x-&gt;badd(1), &quot; &quot;, $y,&quot;\n&quot;;        # prints 10 10</pre>
 128 <pre>
 129         $x = 9; $y = $x;
 130         print $x-&gt;binc(1), &quot; &quot;, $y,&quot;\n&quot;;        # prints 10 10</pre>
 131 <pre>
 132         $x = 9; $y = $x;
 133         print $x-&gt;bmul(2), &quot; &quot;, $y,&quot;\n&quot;;        # prints 18 18</pre>
 134 <p>Using methods that do not modify, but testthe contents works:</p>
 135 <pre>
 136         $x = 9; $y = $x;
 137         $z = 9 if $x-&gt;is_zero();                # works fine</pre>
 138 <p>See the documentation about the copy constructor and <code>=</code> in overload, as
 139 well as the documentation in BigInt for further details.</p>
 140 <p>
 141 </p>
 142 <h2><a name="options">Options</a></h2>
 143 <p>bignum recognizes some options that can be passed while loading it via use.
 144 The options can (currently) be either a single letter form, or the long form.
 145 The following options exist:</p>
 146 <dl>
 147 <dt><strong><a name="item_a_or_accuracy">a or accuracy</a></strong>
 148
 149 <dd>
 150 <p>This sets the accuracy for all math operations. The argument must be greater
 151 than or equal to zero. See Math::BigInt's <code>bround()</code> function for details.</p>
 152 </dd>
 153 <dd>
 154 <pre>
 155         perl -Mbigrat=a,50 -le 'print sqrt(20)'</pre>
 156 </dd>
 157 </li>
 158 <dt><strong><a name="item_p_or_precision">p or precision</a></strong>
 159
 160 <dd>
 161 <p>This sets the precision for all math operations. The argument can be any
 162 integer. Negative values mean a fixed number of digits after the dot, while
 163 a positive value rounds to this digit left from the dot. 0 or 1 mean round to
 164 integer. See Math::BigInt's <code>bfround()</code> function for details.</p>
 165 </dd>
 166 <dd>
 167 <pre>
 168         perl -Mbigrat=p,-50 -le 'print sqrt(20)'</pre>
 169 </dd>
 170 </li>
 171 <dt><strong><a name="item_t_or_trace">t or trace</a></strong>
 172
 173 <dd>
 174 <p>This enables a trace mode and is primarily for debugging bignum or
 175 Math::BigInt/Math::BigFloat.</p>
 176 </dd>
 177 </li>
 178 <dt><strong><a name="item_l_or_lib">l or lib</a></strong>
 179
 180 <dd>
 181 <p>Load a different math lib, see <a href="#math_library">MATH LIBRARY</a>.</p>
 182 </dd>
 183 <dd>
 184 <pre>
 185         perl -Mbigrat=l,GMP -e 'print 2 ** 512'</pre>
 186 </dd>
 187 <dd>
 188 <p>Currently there is no way to specify more than one library on the command
 189 line. This will be hopefully fixed soon ;)</p>
 190 </dd>
 191 </li>
 192 <dt><strong><a name="item_v_or_version">v or version</a></strong>
 193
 194 <dd>
 195 <p>This prints out the name and version of all modules used and then exits.</p>
 196 </dd>
 197 <dd>
 198 <pre>
 199         perl -Mbigrat=v</pre>
 200 </dd>
 201 </li>
 202 </dl>
 203 <p>
 204 </p>
 205 <hr />
 206 <h1><a name="examples">EXAMPLES</a></h1>
 207 <pre>
 208
 209         perl -Mbigrat -le 'print sqrt(33)'
 210         perl -Mbigrat -le 'print 2*255'
 211         perl -Mbigrat -le 'print 4.5+2*255'
 212         perl -Mbigrat -le 'print 3/7 + 5/7 + 8/3'
 213         perl -Mbigrat -le 'print 12-&gt;is_odd()';</pre>
 214 <p>
 215 </p>
 216 <hr />
 217 <h1><a name="license">LICENSE</a></h1>
 218 <p>This program is free software; you may redistribute it and/or modify it under
 219 the same terms as Perl itself.</p>
 220 <p>
 221 </p>
 222 <hr />
 223 <h1><a name="see_also">SEE ALSO</a></h1>
 224 <p>Especially <a href="file://C|\msysgit\mingw\html/lib/bignum.html">the bignum manpage</a>.</p>
 225 <p><a href="file://C|\msysgit\mingw\html/lib/Math/BigFloat.html">the Math::BigFloat manpage</a>, <a href="file://C|\msysgit\mingw\html/lib/Math/BigInt.html">the Math::BigInt manpage</a>, <a href="file://C|\msysgit\mingw\html/lib/Math/BigRat.html">the Math::BigRat manpage</a> and <a href="file://C|\msysgit\mingw\html/Math/Big.html">the Math::Big manpage</a> as well
 226 as <a href="file://C|\msysgit\mingw\html/Math/BigInt/BitVect.html">the Math::BigInt::BitVect manpage</a>, <a href="file://C|\msysgit\mingw\html/Math/BigInt/Pari.html">the Math::BigInt::Pari manpage</a> and  <a href="file://C|\msysgit\mingw\html/Math/BigInt/GMP.html">the Math::BigInt::GMP manpage</a>.</p>
 227 <p>
 228 </p>
 229 <hr />
 230 <h1><a name="authors">AUTHORS</a></h1>
 231 <p>(C) by Tels <a href="http://bloodgate.com/">http://bloodgate.com/</a> in early 2002 - 2005.</p>
 232 <table border="0" width="100%" cellspacing="0" cellpadding="3">
 233 <tr><td class="block" style="background-color: #cccccc" valign="middle">
 234 <big><strong><span class="block">&nbsp;bigrat - Transparent BigNumber/BigRational support for Perl</span></strong></big>
 235 </td></tr>
 236 </table>
 237
 238 </body>
 239
 240 </html>