NAME
    cos - cosine

SYNOPSIS
    cos(x [,eps])

TYPES
    x		number (real or complex)
    eps		nonzero real, defaults to epsilon()

    return	number

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

EXAMPLE
    > print cos(1, 1e-5), cos(1, 1e-10), cos(1, 1e-15), cos(1, 1e-20)
    .5403 .5403023059 .54030230586814 .5403023058681397174

    > print cos(2 +3i, 1e-5), cos(2 + 3i, 1e-10)
    -4.18963-9.10923i -4.189625691-9.1092278938i

    > pi = pi(1e-20)
    > print cos(pi/3, 1e-10), cos(pi/2, 1e-10), cos(pi, 1e-10)
    .5 0 -1

LIMITS
    none

LIBRARY
    NUMBER *qcos(NUMBER *x, NUMBER *eps)
    COMPLEX *ccos(COMPLEX *x, NUMBER *eps)

SEE ALSO
    sin, tan, sec, csc, cot, epsilon