double
     acos(double x);

     long double
     acosl(long double x);

     float
     acosf(float x);

DESCRIPTION

     The acos() function computes the principle value of the arc cosine of x.
     The result is 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)

STANDARDS

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

BSD                            November 14, 2002                           BSD