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.\"     Title: atan
.\"    Author: [FIXME: author] [see http://www.docbook.org/tdg5/en/html/author]
.\" Generator: DocBook XSL Stylesheets v1.79.2 <http://docbook.sf.net/>
.\"      Date: 10/20/2024
.\"    Manual: [FIXME: manual]
.\"    Source: [FIXME: source]
.\"  Language: English
.\"
.TH "ATAN" "3G" "10/20/2024" "[FIXME: source]" "[FIXME: manual]"
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.SH "NAME"
atan \- return the arc\-tangent of the parameters
.SH "DECLARATION"
.HP \w'genType\ atan('u
.BI "genType atan(genType\ " "y" ", genType\ " "x" ");"
.HP \w'genType\ atan('u
.BI "genType atan(genType\ " "y_over_x" ");"
.SH "PARAMETERS"
.PP
\fIy\fR
.RS 4
Specify the numerator of the fraction whose arctangent to return\&.
.RE
.PP
\fIx\fR
.RS 4
Specify the denominator of the fraction whose arctangent to return\&.
.RE
.PP
\fIy_over_x\fR
.RS 4
Specify the fraction whose arctangent to return\&.
.RE
.SH "DESCRIPTION"
.PP
\fBatan\fR
returns either the angle whose trigonometric arctangent is $y \eover x$ or
\fIy_over_x\fR, depending on which overload is invoked\&. In the first overload, the signs of $y$ and $x$ are used to determine the quadrant that the angle lies in\&. The value returned by
\fBatan\fR
in this case is in the range $[\-\epi,\epi]$\&. The result is undefined if $x = 0$\&.
.PP
For the second overload,
\fBatan\fR
returns the angle whose tangent is
\fIy_over_x\fR\&. The value returned in this case is in the range $[\-{\epi \eover 2 },{\epi \eover 2}]$\&.
.SH "VERSION SUPPORT"
.TS
allbox tab(:);
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lB cB cB cB cB cB cB cB cB cB cB cB cB.
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\fBFunction Name\fR
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\fB1\&.10\fR
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\fB1\&.20\fR
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\fB1\&.30\fR
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\fB1\&.40\fR
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\fB1\&.50\fR
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\fB3\&.30\fR
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\fB4\&.00\fR
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\fB4\&.10\fR
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\fB4\&.20\fR
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\fB4\&.30\fR
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\fB4\&.40\fR
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\fB4\&.50\fR
T}
.T&
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T{
atan
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.TE
.sp 1
.SH "SEE ALSO"
.PP
\fBsin\fR(),
\fBcos\fR(),
\fBtan\fR()
.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]\fBhttps://opencontent\&.org/openpub/\fR\m[]\&.
.SH "COPYRIGHT"
.br
Copyright \(co 2011-2014 Khronos Group
.br