NAME
    atan - inverse trigonometric tangent

SYNOPSIS
    atan(x [,eps])

TYPES
    x		real
    eps		nonzero real, defaults to epsilon()

    return	real

DESCRIPTION
    Returns the atan of x to a multiple of eps with error less in
    absolute value than .75 * eps.

    v = atan(x) is the number in (-p1/2, pi/2) for which tan(v) = x.

EXAMPLE
    > print atan(2, 1e-5), atan(2, 1e-10), atan(2, 1e-15), atan(2, 1e-20)
    1.10715 1.1071487178 1.107148717794091 1.10714871779409050302

LIMITS
    unlike sin and cos, x must be real
    eps > 0

LIBRARY
    NUMBER *qatan(NUMBER *x, NUMBER *eps)

SEE ALSO
    asin, acos, asec, acsc, acot, epsilon