numerical.sgml

GLib是GTK+和GNOME工程的基础底层核心程序库

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Numerical Definitions

<!-- ##### SECTION Short_Description ##### -->
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, for reference: <ulink url="http://twister.ou.edu/workshop.docs/common-tools/numerical_comp_guide/ncg_math.doc.html">http://twister.ou.edu/workshop.docs/common-tools/numerical_comp_guide/ncg_math.doc.html</ulink>
</para>

<!-- ##### SECTION See_Also ##### -->
<para>
<ulink url="http://twister.ou.edu/workshop.docs/common-tools/numerical_comp_guide/ncg_math.doc.html">http://twister.ou.edu/workshop.docs/common-tools/numerical_comp_guide/ncg_math.doc.html</ulink>
</para>

<!-- ##### MACRO G_IEEE754_FLOAT_BIAS ##### -->
<para>
See <ulink url="http://twister.ou.edu/workshop.docs/common-tools/numerical_comp_guide/ncg_math.doc.html">http://twister.ou.edu/workshop.docs/common-tools/numerical_comp_guide/ncg_math.doc.html</ulink>
</para>



<!-- ##### MACRO G_IEEE754_DOUBLE_BIAS ##### -->
<para>
See <ulink url="http://twister.ou.edu/workshop.docs/common-tools/numerical_comp_guide/ncg_math.doc.html">http://twister.ou.edu/workshop.docs/common-tools/numerical_comp_guide/ncg_math.doc.html</ulink>
</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, for reference: 
<ulink url="http://twister.ou.edu/workshop.docs/common-tools/numerical_comp_guide/ncg_math.doc.html">http://twister.ou.edu/workshop.docs/common-tools/numerical_comp_guide/ncg_math.doc.html</ulink>
</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, for reference: 
<ulink url="http://twister.ou.edu/workshop.docs/common-tools/numerical_comp_guide/ncg_math.doc.html">http://twister.ou.edu/workshop.docs/common-tools/numerical_comp_guide/ncg_math.doc.html</ulink>
</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>
Used for fooling around with float formats, see 
<ulink url="http://twister.ou.edu/workshop.docs/common-tools/numerical_comp_guide/ncg_math.doc.html">http://twister.ou.edu/workshop.docs/common-tools/numerical_comp_guide/ncg_math.doc.html</ulink>
</para>