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renderer=
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"Content-Type" content=
"text/html; charset=UTF-8" /><link rel=
"stylesheet" type=
"text/css" href=
"opengl-man.css" /><title>fma - OpenGL Shading Language (GLSL)
</title><meta name=
"generator" content=
"DocBook XSL Stylesheets V1.69.1" /></head><body><div class=
"refentry" lang=
"en" xml:
lang=
"en"><a id=
"fma"></a><div class=
"titlepage"></div><div class=
"refnamediv"><h2>Name
</h2><p>fma — perform a fused multiply-add operation
</p></div><div class=
"refsynopsisdiv"><h2>Declaration
</h2><div class=
"funcsynopsis"><p><code class=
"funcdef">genType
<b class=
"fsfunc">fma
</b>(
</code>genType
<var class=
"pdparam">a
</var>, genType
<var class=
"pdparam">b
</var>, genType
<var class=
"pdparam">c
</var><code>)
</code>;
</p><table border=
"0" summary=
"Function synopsis" cellspacing=
"0" cellpadding=
"0"><tr><td><code class=
"funcdef">genDType
<b class=
"fsfunc">fma
</b>(
</code></td><td>genDType
</td><td><var class=
"pdparam">a
</var>,
</td></tr><tr><td> </td><td>genDType
</td><td><var class=
"pdparam">b
</var>,
</td></tr><tr><td> </td><td>genDType
</td><td><var class=
"pdparam">c
</var><code>)
</code>;
</td></tr></table></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"parameters"></a><h2>Parameters
</h2><div class=
"variablelist"><dl><dt><span class=
"term"><em class=
"parameter"><code>a
</code></em></span></dt><dd><p>
5 Specifies the first multiplicand.
6 </p></dd><dt><span class=
"term"><em class=
"parameter"><code>b
</code></em></span></dt><dd><p>
7 Specifies the second multiplicand.
8 </p></dd><dt><span class=
"term"><em class=
"parameter"><code>c
</code></em></span></dt><dd><p>
9 Specifies the value to be added to the result.
10 </p></dd></dl></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"description"></a><h2>Description
</h2><p>
11 <code class=
"function">fma
</code> performs, where possible, a fused multiply-add operation,
12 returning
<code class=
"code">a * b + c
</code>.
13 In use cases where the return value is eventually consumed by a variable declared as
14 <code class=
"code">precise
</code>:
15 </p><div class=
"itemizedlist"><ul type=
"disc"><li><code class=
"function">fma
</code>() is considered a single operation, whereas the
16 expression
<code class=
"code">a * b + c
</code> consumed by a variable declared as
<code class=
"code">precise
</code>
17 is considered two operations.
</li><li>The precision of
<code class=
"function">fma
</code>() can differ from the precision
18 of the expression
<code class=
"code">a * b + c
</code>.
</li><li><code class=
"function">fma
</code>() will be computed with the same precision as any
19 other
<code class=
"function">fma
</code>() consumed by a
<code class=
"code">precise
</code> variable,
20 giving invariant results for the same input values of
<em class=
"parameter"><code>a
</code></em>,
21 <em class=
"parameter"><code>b
</code></em> and
<em class=
"parameter"><code>c
</code></em>.
</li></ul></div><p>
22 Otherwise, in the absense of
<code class=
"code">precise
</code> consumption, there are no
23 special constraints on the number of operations or difference in precision between
24 <code class=
"function">fma
</code>() and the expression
<code class=
"code">a * b + c
</code>.
25 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"versions"></a><h2>Version Support
</h2><div class=
"informaltable"><table border=
"1"><colgroup><col align=
"left" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /></colgroup><thead><tr><th align=
"left"><span class=
"bold"><strong>Function
</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
1.10</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
1.20</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
1.30</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
1.40</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
1.50</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
3.30</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
4.00</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
4.10</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
4.20</strong></span></th><th align=
"center"><span class=
"bold"><strong>Version
4.30</strong></span></th></tr><tr><th align=
"left">fma (genType)
</th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th></tr><tr><th align=
"left">fma (genDType)
</th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th></tr></thead></table></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"Copyright"></a><h2>Copyright
</h2><p>
26 Copyright
<span class=
"trademark"></span>©
2011 Khronos Group.
27 This material may be distributed subject to the terms and conditions set forth in
28 the Open Publication License, v
1.0,
8 June
1999.
29 <a href=
"http://opencontent.org/openpub/" target=
"_top">http://opencontent.org/openpub/
</a>.
30 </p></div></div></body></html>