NAME
    acos - arc cosine

SYNOPSIS
    acos(x [,acc])

TYPES
    x		real
    acc		real

    return	real

DESCRIPTION
    Calculate the arc cosine of x with an accuracy within eps.
    By default, eps is epsilon().

    The result is in the range [0, pi].

EXAMPLE
    > print acos(-1), acos(0), acos(2^-37)
    ~3.14159265358979323846 ~1.57079632679489661923 ~1.57079632678762066161

    > print acos(0.4), acos(0.4, 0.01), acos(cos(1), 0.001)
    ~1.15927948072740859984 ~1.15921735763549804687 ~1.00000429153442382812

LIMITS
    -1 <= x <= 1
    acc > 0

LIBRARY
    NUMBER *qacos(NUMBER *x, *acc)

SEE ALSO
    asin, atan, atan2, cos, epsilon, sin, tan
