'\" t
.\"     Title: fma
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: 01/03/2018
.\"    Manual: [FIXME: manual]
.\"    Source: [FIXME: source]
.\"  Language: English
.\"
.TH "FMA" "3G" "01/03/2018" "[FIXME: source]" "[FIXME: manual]"
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.nh
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.\" * MAIN CONTENT STARTS HERE *
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.SH "NAME"
fma \- perform a fused multiply\-add operation
.SH "DECLARATION"
.HP \w'genType\ fma('u
.BI "genType fma(genType\ " "a" ", genType\ " "b" ", genType\ " "c" ");"
.HP \w'genDType\ fma('u
.BI "genDType fma(genDType\ " "a" ", genDType\ " "b" ", genDType\ " "c" ");"
.SH "PARAMETERS"
.PP
\fIa\fR
.RS 4
Specifies the first multiplicand\&.
.RE
.PP
\fIb\fR
.RS 4
Specifies the second multiplicand\&.
.RE
.PP
\fIc\fR
.RS 4
Specifies the value to be added to the result\&.
.RE
.SH "DESCRIPTION"
.PP
\fBfma\fR
performs, where possible, a fused multiply\-add operation, returning
a * b + c\&. In use cases where the return value is eventually consumed by a variable declared as
precise:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\fBfma\fR() is considered a single operation, whereas the expression
a * b + c
consumed by a variable declared as
precise
is considered two operations\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
The precision of
\fBfma\fR() can differ from the precision of the expression
a * b + c\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\fBfma\fR() will be computed with the same precision as any other
\fBfma\fR() consumed by a
precise
variable, giving invariant results for the same input values of
\fIa\fR,
\fIb\fR
and
\fIc\fR\&.
.RE
.sp
Otherwise, in the absense of
precise
consumption, there are no special constraints on the number of operations or difference in precision between
\fBfma\fR() and the expression
a * b + c\&.
.SH "VERSION SUPPORT"
.TS
allbox tab(:);
lB cB s s s s s s s s s s s
lB cB cB cB cB cB cB cB cB cB cB cB cB.
T{

T}:T{
\fBOpenGL Shading Language Version\fR
T}
T{
\fBFunction Name\fR
T}:T{
\fB1\&.10\fR
T}:T{
\fB1\&.20\fR
T}:T{
\fB1\&.30\fR
T}:T{
\fB1\&.40\fR
T}:T{
\fB1\&.50\fR
T}:T{
\fB3\&.30\fR
T}:T{
\fB4\&.00\fR
T}:T{
\fB4\&.10\fR
T}:T{
\fB4\&.20\fR
T}:T{
\fB4\&.30\fR
T}:T{
\fB4\&.40\fR
T}:T{
\fB4\&.50\fR
T}
.T&
l c c c c c c c c c c c c
l c c c c c c c c c c c c.
T{
fma (genType)
T}:T{
\-
T}:T{
\-
T}:T{
\-
T}:T{
\-
T}:T{
\-
T}:T{
\-
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}
T{
fma (genDType)
T}:T{
\-
T}:T{
\-
T}:T{
\-
T}:T{
\-
T}:T{
\-
T}:T{
\-
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}:T{
✔
T}
.TE
.sp 1
.SH "COPYRIGHT"
.PP
Copyright
\(co
2011\-2014 Khronos Group\&. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1\&.0, 8 June 1999\&.
\m[blue]\fBhttp://opencontent\&.org/openpub/\fR\m[]\&.
.SH "COPYRIGHT"
.br
Copyright \(co 2011-2014 Khronos Group
.br