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atan2f(3m) [sunos man page]

atan2(3M)						  Mathematical Library Functions						 atan2(3M)

NAME
atan2, atan2f, atan2l - arc tangent function SYNOPSIS
cc [ flag... ] file... -lm [ library... ] #include <math.h> double atan2(double y, double x); float atan2f(float y, float x); long double atan2l(long double y, long double x); DESCRIPTION
These functions compute the principal value of the arc tangent of y/x, using the signs of both arguments to determine the quadrant of the return value. RETURN VALUES
Upon successful completion, these functions return the arc tangent of y/x in the range [ -, ] radians. If y is +-0 and x is < 0, +- is returned. If y is +-0 and x is > 0, +-0 is returned. If y is < 0 and x is +-0, -/2 is returned. If y is > 0 and x is +-0, /2 is returned. If x is 0, a pole error does not occur. If either x or y is NaN, a NaN is returned. If y is +-0 and x is -0, +- is returned. If y is +-0 and x is +0, +-0 is returned. For finite values of +-y > 0, if x is -Inf, +- is returned. For finite values of +-y > 0, if x is +Inf, +-0 is returned. For finite values of x, if y is +-Inf, +-/2 is returned. If y is +-Inf and x is -Inf, +-3/4 is returned. If y is +-Inf and x is +Inf, +-/4 is returned. If both arguments are 0, a domain error does not occur. ERRORS
No errors are defined. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
atan(3M), isnan(3M), math.h(3HEAD)tan(3M), attributes(5), standards(5) SunOS 5.10 1 Sep 2002 atan2(3M)

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ATAN2(3)						     Linux Programmer's Manual							  ATAN2(3)

NAME
atan2, atan2f, atan2l - arc tangent function of two variables SYNOPSIS
#include <math.h> double atan2(double y, double x); float atan2f(float y, float x); long double atan2l(long double y, long double x); Link with -lm. Feature Test Macro Requirements for glibc (see feature_test_macros(7)): atan2f(), atan2l(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE DESCRIPTION
These functions calculate the principal value of the arc tangent of y/x, using the signs of the two arguments to determine the quadrant of the result. RETURN VALUE
On success, these functions return the principal value of the arc tangent of y/x in radians; the return value is in the range [-pi, pi]. If y is +0 (-0) and x is less than 0, +pi (-pi) is returned. If y is +0 (-0) and x is greater than 0, +0 (-0) is returned. If y is less than 0 and x is +0 or -0, -pi/2 is returned. If y is greater than 0 and x is +0 or -0, pi/2 is returned. If either x or y is NaN, a NaN is returned. If y is +0 (-0) and x is -0, +pi (-pi) is returned. If y is +0 (-0) and x is +0, +0 (-0) is returned. If y is a finite value greater (less) than 0, and x is negative infinity, +pi (-pi) is returned. If y is a finite value greater (less) than 0, and x is positive infinity, +0 (-0) is returned. If y is positive infinity (negative infinity), and x is finite, pi/2 (-pi/2) is returned. If y is positive infinity (negative infinity) and x is negative infinity, +3*pi/4 (-3*pi/4) is returned. If y is positive infinity (negative infinity) and x is positive infinity, +pi/4 (-pi/4) is returned. ERRORS
No errors occur. ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7). +-----------------------------+---------------+---------+ |Interface | Attribute | Value | +-----------------------------+---------------+---------+ |atan2(), atan2f(), atan2l() | Thread safety | MT-Safe | +-----------------------------+---------------+---------+ CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008. The variant returning double also conforms to SVr4, 4.3BSD, C89. SEE ALSO
acos(3), asin(3), atan(3), carg(3), cos(3), sin(3), tan(3) COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/. 2017-09-15 ATAN2(3)
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