docs/reference/glib/tmpl/numerical.sgml

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Numerical Definitions

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mathematical constants, and floating point decomposition

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<para>
GLib offers mathematical constants such as #G_PI for the value of pi;
many platforms have these in the C library, but some don't, the GLib
versions always exist.
</para>

<para>
The #GFloatIEEE754 and #GDoubleIEEE754 unions are used to access the
sign, mantissa and exponent of IEEE floats and doubles. These unions are
defined as appropriate for a given platform. IEEE floats and doubles are
supported (used for storage) by at least Intel, PPC and Sparc. See
<ulink url="http://en.wikipedia.org/wiki/IEEE_float">IEEE 754-2008</ulink>
for more information about IEEE number formats.
</para>

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<para>

</para>

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<!-- ##### MACRO G_IEEE754_FLOAT_BIAS ##### -->
<para>
The bias by which exponents in single-precision floats are offset.
</para>



<!-- ##### MACRO G_IEEE754_DOUBLE_BIAS ##### -->
<para>
The bias by which exponents in double-precision floats are offset.
</para>



<!-- ##### UNION GFloatIEEE754 ##### -->
<para>
The #GFloatIEEE754 and #GDoubleIEEE754 unions are used to access the sign,
mantissa and exponent of IEEE floats and doubles. These unions are defined
as appropriate for a given platform. IEEE floats and doubles are supported
(used for storage) by at least Intel, PPC and Sparc.
</para>


<!-- ##### UNION GDoubleIEEE754 ##### -->
<para>
The #GFloatIEEE754 and #GDoubleIEEE754 unions are used to access the sign,
mantissa and exponent of IEEE floats and doubles. These unions are defined
as appropriate for a given platform. IEEE floats and doubles are supported
(used for storage) by at least Intel, PPC and Sparc.
</para>


<!-- ##### MACRO G_E ##### -->
<para>
The base of natural logarithms.
</para>



<!-- ##### MACRO G_LN2 ##### -->
<para>
The natural logarithm of 2.
</para>



<!-- ##### MACRO G_LN10 ##### -->
<para>
The natural logarithm of 10.
</para>



<!-- ##### MACRO G_PI ##### -->
<para>
The value of pi (ratio of circle's circumference to its diameter).
</para>



<!-- ##### MACRO G_PI_2 ##### -->
<para>
Pi divided by 2.
</para>



<!-- ##### MACRO G_PI_4 ##### -->
<para>
Pi divided by 4.
</para>



<!-- ##### MACRO G_SQRT2 ##### -->
<para>
The square root of two.
</para>



<!-- ##### MACRO G_LOG_2_BASE_10 ##### -->
<para>
Multiplying the base 2 exponent by this number yields the base 10 exponent.
</para>