271 lines
4.8 KiB
HTML
271 lines
4.8 KiB
HTML
|
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
|
|
<HTML><HEAD><TITLE>Man page of ATAN2</TITLE>
|
|
</HEAD><BODY>
|
|
<H1>ATAN2</H1>
|
|
Section: Linux Programmer's Manual (3)<BR>Updated: 2017-09-15<BR><A HREF="#index">Index</A>
|
|
<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
|
|
|
|
<A NAME="lbAB"> </A>
|
|
<H2>NAME</H2>
|
|
|
|
atan2, atan2f, atan2l - arc tangent function of two variables
|
|
<A NAME="lbAC"> </A>
|
|
<H2>SYNOPSIS</H2>
|
|
|
|
<PRE>
|
|
<B>#include <<A HREF="file:///usr/include/math.h">math.h</A>></B>
|
|
|
|
<B>double atan2(double </B><I>y</I><B>, double </B><I>x</I><B>);</B>
|
|
<B>float atan2f(float </B><I>y</I><B>, float </B><I>x</I><B>);</B>
|
|
<B>long double atan2l(long double </B><I>y</I><B>, long double </B><I>x</I><B>);</B>
|
|
</PRE>
|
|
|
|
<P>
|
|
|
|
Link with <I>-lm</I>.
|
|
<P>
|
|
|
|
|
|
Feature Test Macro Requirements for glibc (see
|
|
<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
|
|
|
|
|
|
<P>
|
|
|
|
|
|
<B>atan2f</B>(),
|
|
|
|
<B>atan2l</B>():
|
|
|
|
<DL COMPACT><DT id="1"><DD>
|
|
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|
|
<BR> || /* Since glibc 2.19: */ _DEFAULT_SOURCE
|
|
<BR> || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
|
|
</DL>
|
|
|
|
|
|
<A NAME="lbAD"> </A>
|
|
<H2>DESCRIPTION</H2>
|
|
|
|
These functions calculate the principal value of the arc tangent of
|
|
<I>y/x</I>,
|
|
|
|
using the signs of the two arguments to determine
|
|
the quadrant of the result.
|
|
<A NAME="lbAE"> </A>
|
|
<H2>RETURN VALUE</H2>
|
|
|
|
On success, these functions return the principal value of the arc tangent of
|
|
<I>y/x</I>
|
|
|
|
in radians; the return value is in the range [-pi, pi].
|
|
<P>
|
|
|
|
If
|
|
<I>y</I>
|
|
|
|
is +0 (-0) and
|
|
<I>x</I>
|
|
|
|
is less than 0, +pi (-pi) is returned.
|
|
<P>
|
|
|
|
If
|
|
<I>y</I>
|
|
|
|
is +0 (-0) and
|
|
<I>x</I>
|
|
|
|
is greater than 0, +0 (-0) is returned.
|
|
<P>
|
|
|
|
If
|
|
<I>y</I>
|
|
|
|
is less than 0 and
|
|
<I>x</I>
|
|
|
|
is +0 or -0, -pi/2 is returned.
|
|
<P>
|
|
|
|
If
|
|
<I>y</I>
|
|
|
|
is greater than 0 and
|
|
<I>x</I>
|
|
|
|
is +0 or -0, pi/2 is returned.
|
|
<P>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
If either
|
|
<I>x</I>
|
|
|
|
or
|
|
<I>y</I>
|
|
|
|
is NaN, a NaN is returned.
|
|
<P>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
If
|
|
<I>y</I>
|
|
|
|
is +0 (-0) and
|
|
<I>x</I>
|
|
|
|
is -0, +pi (-pi) is returned.
|
|
<P>
|
|
|
|
If
|
|
<I>y</I>
|
|
|
|
is +0 (-0) and
|
|
<I>x</I>
|
|
|
|
is +0, +0 (-0) is returned.
|
|
<P>
|
|
|
|
If
|
|
<I>y</I>
|
|
|
|
is a finite value greater (less) than 0, and
|
|
<I>x</I>
|
|
|
|
is negative infinity, +pi (-pi) is returned.
|
|
<P>
|
|
|
|
If
|
|
<I>y</I>
|
|
|
|
is a finite value greater (less) than 0, and
|
|
<I>x</I>
|
|
|
|
is positive infinity, +0 (-0) is returned.
|
|
<P>
|
|
|
|
If
|
|
<I>y</I>
|
|
|
|
is positive infinity (negative infinity), and
|
|
<I>x</I>
|
|
|
|
is finite,
|
|
pi/2 (-pi/2) is returned.
|
|
<P>
|
|
|
|
If
|
|
<I>y</I>
|
|
|
|
is positive infinity (negative infinity) and
|
|
<I>x</I>
|
|
|
|
is negative infinity, +3*pi/4 (-3*pi/4) is returned.
|
|
<P>
|
|
|
|
If
|
|
<I>y</I>
|
|
|
|
is positive infinity (negative infinity) and
|
|
<I>x</I>
|
|
|
|
is positive infinity, +pi/4 (-pi/4) is returned.
|
|
|
|
|
|
|
|
<A NAME="lbAF"> </A>
|
|
<H2>ERRORS</H2>
|
|
|
|
No errors occur.
|
|
|
|
|
|
<A NAME="lbAG"> </A>
|
|
<H2>ATTRIBUTES</H2>
|
|
|
|
For an explanation of the terms used in this section, see
|
|
<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
|
|
|
|
<TABLE BORDER>
|
|
<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
|
|
<TR VALIGN=top><TD>
|
|
<B>atan2</B>(),
|
|
|
|
<B>atan2f</B>(),
|
|
|
|
<B>atan2l</B>()
|
|
|
|
</TD><TD>Thread safety</TD><TD>MT-Safe<BR></TD></TR>
|
|
</TABLE>
|
|
|
|
<A NAME="lbAH"> </A>
|
|
<H2>CONFORMING TO</H2>
|
|
|
|
C99, POSIX.1-2001, POSIX.1-2008.
|
|
<P>
|
|
|
|
The variant returning
|
|
<I>double</I>
|
|
|
|
also conforms to
|
|
SVr4, 4.3BSD, C89.
|
|
<A NAME="lbAI"> </A>
|
|
<H2>SEE ALSO</H2>
|
|
|
|
<B><A HREF="/cgi-bin/man/man2html?3+acos">acos</A></B>(3),
|
|
|
|
<B><A HREF="/cgi-bin/man/man2html?3+asin">asin</A></B>(3),
|
|
|
|
<B><A HREF="/cgi-bin/man/man2html?3+atan">atan</A></B>(3),
|
|
|
|
<B><A HREF="/cgi-bin/man/man2html?3+carg">carg</A></B>(3),
|
|
|
|
<B><A HREF="/cgi-bin/man/man2html?3+cos">cos</A></B>(3),
|
|
|
|
<B><A HREF="/cgi-bin/man/man2html?3+sin">sin</A></B>(3),
|
|
|
|
<B><A HREF="/cgi-bin/man/man2html?3+tan">tan</A></B>(3)
|
|
|
|
<A NAME="lbAJ"> </A>
|
|
<H2>COLOPHON</H2>
|
|
|
|
This page is part of release 5.05 of the Linux
|
|
<I>man-pages</I>
|
|
|
|
project.
|
|
A description of the project,
|
|
information about reporting bugs,
|
|
and the latest version of this page,
|
|
can be found at
|
|
<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
|
|
<P>
|
|
|
|
<HR>
|
|
<A NAME="index"> </A><H2>Index</H2>
|
|
<DL>
|
|
<DT id="2"><A HREF="#lbAB">NAME</A><DD>
|
|
<DT id="3"><A HREF="#lbAC">SYNOPSIS</A><DD>
|
|
<DT id="4"><A HREF="#lbAD">DESCRIPTION</A><DD>
|
|
<DT id="5"><A HREF="#lbAE">RETURN VALUE</A><DD>
|
|
<DT id="6"><A HREF="#lbAF">ERRORS</A><DD>
|
|
<DT id="7"><A HREF="#lbAG">ATTRIBUTES</A><DD>
|
|
<DT id="8"><A HREF="#lbAH">CONFORMING TO</A><DD>
|
|
<DT id="9"><A HREF="#lbAI">SEE ALSO</A><DD>
|
|
<DT id="10"><A HREF="#lbAJ">COLOPHON</A><DD>
|
|
</DL>
|
|
<HR>
|
|
This document was created by
|
|
<A HREF="/cgi-bin/man/man2html">man2html</A>,
|
|
using the manual pages.<BR>
|
|
Time: 00:05:36 GMT, March 31, 2021
|
|
</BODY>
|
|
</HTML>
|