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  26 <a name="glib-Numerical-Definitions"></a><div class="titlepage"></div>
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  29 <h2><span class="refentrytitle"><a name="glib-Numerical-Definitions.top_of_page"></a>Numerical Definitions</span></h2>
  30 <p>Numerical Definitions — mathematical constants, and floating point decomposition</p>
  31 </td>
  32 <td class="gallery_image" valign="top" align="right"></td>
  33 </tr></table></div>
  34 <div class="refsect1">
  35 <a name="glib-Numerical-Definitions.other"></a><h2>Types and Values</h2>
  36 <div class="informaltable"><table class="informaltable" width="100%" border="0">
  37 <colgroup>
  38 <col width="150px" class="name">
  39 <col class="description">
  40 </colgroup>
  41 <tbody>
  42 <tr>
  43 <td class="define_keyword">#define</td>
  44 <td class="function_name"><a class="link" href="glib-Numerical-Definitions.html#G-IEEE754-FLOAT-BIAS:CAPS" title="G_IEEE754_FLOAT_BIAS">G_IEEE754_FLOAT_BIAS</a></td>
  45 </tr>
  46 <tr>
  47 <td class="define_keyword">#define</td>
  48 <td class="function_name"><a class="link" href="glib-Numerical-Definitions.html#G-IEEE754-DOUBLE-BIAS:CAPS" title="G_IEEE754_DOUBLE_BIAS">G_IEEE754_DOUBLE_BIAS</a></td>
  49 </tr>
  50 <tr>
  51 <td class="datatype_keyword">union</td>
  52 <td class="function_name"><a class="link" href="glib-Numerical-Definitions.html#GFloatIEEE754" title="union GFloatIEEE754">GFloatIEEE754</a></td>
  53 </tr>
  54 <tr>
  55 <td class="datatype_keyword">union</td>
  56 <td class="function_name"><a class="link" href="glib-Numerical-Definitions.html#GDoubleIEEE754" title="union GDoubleIEEE754">GDoubleIEEE754</a></td>
  57 </tr>
  58 <tr>
  59 <td class="define_keyword">#define</td>
  60 <td class="function_name"><a class="link" href="glib-Numerical-Definitions.html#G-E:CAPS" title="G_E">G_E</a></td>
  61 </tr>
  62 <tr>
  63 <td class="define_keyword">#define</td>
  64 <td class="function_name"><a class="link" href="glib-Numerical-Definitions.html#G-LN2:CAPS" title="G_LN2">G_LN2</a></td>
  65 </tr>
  66 <tr>
  67 <td class="define_keyword">#define</td>
  68 <td class="function_name"><a class="link" href="glib-Numerical-Definitions.html#G-LN10:CAPS" title="G_LN10">G_LN10</a></td>
  69 </tr>
  70 <tr>
  71 <td class="define_keyword">#define</td>
  72 <td class="function_name"><a class="link" href="glib-Numerical-Definitions.html#G-PI:CAPS" title="G_PI">G_PI</a></td>
  73 </tr>
  74 <tr>
  75 <td class="define_keyword">#define</td>
  76 <td class="function_name"><a class="link" href="glib-Numerical-Definitions.html#G-PI-2:CAPS" title="G_PI_2">G_PI_2</a></td>
  77 </tr>
  78 <tr>
  79 <td class="define_keyword">#define</td>
  80 <td class="function_name"><a class="link" href="glib-Numerical-Definitions.html#G-PI-4:CAPS" title="G_PI_4">G_PI_4</a></td>
  81 </tr>
  82 <tr>
  83 <td class="define_keyword">#define</td>
  84 <td class="function_name"><a class="link" href="glib-Numerical-Definitions.html#G-SQRT2:CAPS" title="G_SQRT2">G_SQRT2</a></td>
  85 </tr>
  86 <tr>
  87 <td class="define_keyword">#define</td>
  88 <td class="function_name"><a class="link" href="glib-Numerical-Definitions.html#G-LOG-2-BASE-10:CAPS" title="G_LOG_2_BASE_10">G_LOG_2_BASE_10</a></td>
  89 </tr>
  90 </tbody>
  91 </table></div>
  92 </div>
  93 <div class="refsect1">
  94 <a name="glib-Numerical-Definitions.includes"></a><h2>Includes</h2>
  95 <pre class="synopsis">#include &lt;glib.h&gt;
  96 </pre>
  97 </div>
  98 <div class="refsect1">
  99 <a name="glib-Numerical-Definitions.description"></a><h2>Description</h2>
 100 <p>GLib offers mathematical constants such as <a class="link" href="glib-Numerical-Definitions.html#G-PI:CAPS" title="G_PI"><span class="type">G_PI</span></a> for the value of pi;
 101 many platforms have these in the C library, but some don't, the GLib
 102 versions always exist.</p>
 103 <p>The <a class="link" href="glib-Numerical-Definitions.html#GFloatIEEE754" title="union GFloatIEEE754"><span class="type">GFloatIEEE754</span></a> and <a class="link" href="glib-Numerical-Definitions.html#GDoubleIEEE754" title="union GDoubleIEEE754"><span class="type">GDoubleIEEE754</span></a> unions are used to access the
 104 sign, mantissa and exponent of IEEE floats and doubles. These unions are
 105 defined as appropriate for a given platform. IEEE floats and doubles are
 106 supported (used for storage) by at least Intel, PPC and Sparc. See
 107 <a class="ulink" href="http://en.wikipedia.org/wiki/IEEE_float" target="_top">IEEE 754-2008</a>
 108 for more information about IEEE number formats.</p>
 109 </div>
 110 <div class="refsect1">
 111 <a name="glib-Numerical-Definitions.functions_details"></a><h2>Functions</h2>
 112 <p></p>
 113 </div>
 114 <div class="refsect1">
 115 <a name="glib-Numerical-Definitions.other_details"></a><h2>Types and Values</h2>
 116 <div class="refsect2">
 117 <a name="G-IEEE754-FLOAT-BIAS:CAPS"></a><h3>G_IEEE754_FLOAT_BIAS</h3>
 118 <pre class="programlisting">#define G_IEEE754_FLOAT_BIAS (127)
 119 </pre>
 120 <p>The bias by which exponents in single-precision floats are offset.</p>
 121 </div>
 122 <hr>
 123 <div class="refsect2">
 124 <a name="G-IEEE754-DOUBLE-BIAS:CAPS"></a><h3>G_IEEE754_DOUBLE_BIAS</h3>
 125 <pre class="programlisting">#define G_IEEE754_DOUBLE_BIAS (1023)
 126 </pre>
 127 <p>The bias by which exponents in double-precision floats are offset.</p>
 128 </div>
 129 <hr>
 130 <div class="refsect2">
 131 <a name="GFloatIEEE754"></a><h3>union GFloatIEEE754</h3>
 132 <p>The <a class="link" href="glib-Numerical-Definitions.html#GFloatIEEE754" title="union GFloatIEEE754"><span class="type">GFloatIEEE754</span></a> and <a class="link" href="glib-Numerical-Definitions.html#GDoubleIEEE754" title="union GDoubleIEEE754"><span class="type">GDoubleIEEE754</span></a> unions are used to access the sign,
 133 mantissa and exponent of IEEE floats and doubles. These unions are defined
 134 as appropriate for a given platform. IEEE floats and doubles are supported
 135 (used for storage) by at least Intel, PPC and Sparc.</p>
 136 <div class="refsect3">
 137 <a name="GFloatIEEE754.members"></a><h4>Members</h4>
 138 <div class="informaltable"><table class="informaltable" width="100%" border="0">
 139 <colgroup>
 140 <col width="300px" class="union_members_name">
 141 <col class="union_members_description">
 142 <col width="200px" class="union_members_annotations">
 143 </colgroup>
 144 <tbody></tbody>
 145 </table></div>
 146 </div>
 147 </div>
 148 <hr>
 149 <div class="refsect2">
 150 <a name="GDoubleIEEE754"></a><h3>union GDoubleIEEE754</h3>
 151 <p>The <a class="link" href="glib-Numerical-Definitions.html#GFloatIEEE754" title="union GFloatIEEE754"><span class="type">GFloatIEEE754</span></a> and <a class="link" href="glib-Numerical-Definitions.html#GDoubleIEEE754" title="union GDoubleIEEE754"><span class="type">GDoubleIEEE754</span></a> unions are used to access the sign,
 152 mantissa and exponent of IEEE floats and doubles. These unions are defined
 153 as appropriate for a given platform. IEEE floats and doubles are supported
 154 (used for storage) by at least Intel, PPC and Sparc.</p>
 155 <div class="refsect3">
 156 <a name="GDoubleIEEE754.members"></a><h4>Members</h4>
 157 <div class="informaltable"><table class="informaltable" width="100%" border="0">
 158 <colgroup>
 159 <col width="300px" class="union_members_name">
 160 <col class="union_members_description">
 161 <col width="200px" class="union_members_annotations">
 162 </colgroup>
 163 <tbody><tr>
 164 <td class="union_member_name"><p><a class="link" href="glib-Basic-Types.html#gdouble" title="gdouble"><span class="type">gdouble</span></a> <em class="structfield"><code><a name="GDoubleIEEE754.v-double"></a>v_double</code></em>;</p></td>
 165 <td class="union_member_description"><p>the double value</p></td>
 166 <td class="union_member_annotations"> </td>
 167 </tr></tbody>
 168 </table></div>
 169 </div>
 170 </div>
 171 <hr>
 172 <div class="refsect2">
 173 <a name="G-E:CAPS"></a><h3>G_E</h3>
 174 <pre class="programlisting">#define G_E     2.7182818284590452353602874713526624977572470937000
 175 </pre>
 176 <p>The base of natural logarithms.</p>
 177 </div>
 178 <hr>
 179 <div class="refsect2">
 180 <a name="G-LN2:CAPS"></a><h3>G_LN2</h3>
 181 <pre class="programlisting">#define G_LN2   0.69314718055994530941723212145817656807550013436026
 182 </pre>
 183 <p>The natural logarithm of 2.</p>
 184 </div>
 185 <hr>
 186 <div class="refsect2">
 187 <a name="G-LN10:CAPS"></a><h3>G_LN10</h3>
 188 <pre class="programlisting">#define G_LN10  2.3025850929940456840179914546843642076011014886288
 189 </pre>
 190 <p>The natural logarithm of 10.</p>
 191 </div>
 192 <hr>
 193 <div class="refsect2">
 194 <a name="G-PI:CAPS"></a><h3>G_PI</h3>
 195 <pre class="programlisting">#define G_PI    3.1415926535897932384626433832795028841971693993751
 196 </pre>
 197 <p>The value of pi (ratio of circle's circumference to its diameter).</p>
 198 </div>
 199 <hr>
 200 <div class="refsect2">
 201 <a name="G-PI-2:CAPS"></a><h3>G_PI_2</h3>
 202 <pre class="programlisting">#define G_PI_2  1.5707963267948966192313216916397514420985846996876
 203 </pre>
 204 <p>Pi divided by 2.</p>
 205 </div>
 206 <hr>
 207 <div class="refsect2">
 208 <a name="G-PI-4:CAPS"></a><h3>G_PI_4</h3>
 209 <pre class="programlisting">#define G_PI_4  0.78539816339744830961566084581987572104929234984378
 210 </pre>
 211 <p>Pi divided by 4.</p>
 212 </div>
 213 <hr>
 214 <div class="refsect2">
 215 <a name="G-SQRT2:CAPS"></a><h3>G_SQRT2</h3>
 216 <pre class="programlisting">#define G_SQRT2 1.4142135623730950488016887242096980785696718753769
 217 </pre>
 218 <p>The square root of two.</p>
 219 </div>
 220 <hr>
 221 <div class="refsect2">
 222 <a name="G-LOG-2-BASE-10:CAPS"></a><h3>G_LOG_2_BASE_10</h3>
 223 <pre class="programlisting">#define G_LOG_2_BASE_10             (0.30102999566398119521)
 224 </pre>
 225 <p>Multiplying the base 2 exponent by this number yields the base 10 exponent.</p>
 226 </div>
 227 </div>
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