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ACOS(3) 						   BSD Library Functions Manual 						   ACOS(3)

NAME
     acos -- arc cosine function

SYNOPSIS
     #include <math.h>

     double
     acos(double x);

DESCRIPTION
     The acos() function computes the principal value of the arc cosine of x in the range [0, pi].

SPECIAL VALUES
     acos(1) returns +0.

     acos(x) returns a NAN and raises the "invalid" floating-point exception for |x| > 1.

SEE ALSO
     sin(3), cos(3), tan(3), asin(3), atan(3), atan2(3), sinh(3), cosh(3), tanh(3), math(3), matherr(3)

STANDARDS
     The acos() function conforms to ISO/IEC 9899:1999(E).

BSD
								 November 14, 2002							       BSD