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acos, acosf, acosl - arc cosine function

#include<math.h>doubleacos(doublex);floatacosf(floatx);longdoubleacosl(longdoublex);Link with-lm. Feature Test Macro Requirements for glibc (seefeature_test_macros(7)):acosf(),acosl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; orcc-std=c99

Theacos() function calculates the arc cosine ofx; that is the value whose cosine isx.

On success, these functions return the arc cosine ofxin radians; the return value is in the range [0, pi]. Ifxis a NaN, a NaN is returned. Ifxis +1, +0 is returned. Ifxis positive infinity or negative infinity, a domain error occurs, and a NaN is returned. Ifxis outside the range [-1, 1], a domain error occurs, and a NaN is returned.

Seemath_error(7) for information on how to determine whether an error has occurred when calling these functions. The following errors can occur: Domain error:xis outside the range [-1, 1]errnois set toEDOM. An invalid floating-point exception (FE_INVALID) is raised.

C99, POSIX.1-2001. The variant returningdoublealso conforms to SVr4, 4.3BSD, C89.

asin(3),atan(3),atan2(3),cacos(3),cos(3),sin(3),tan(3)

This page is part of release 3.24 of the Linuxman-pagesproject. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. 2008-08-05