NAME
    tanh - hyperbolic tangent

SYNOPSIS
    tanh(x [,acc])

TYPES
    x		real
    acc		real

    return	real

DESCRIPTION
    Calculate the hyperbolic tangent of x with an accuracy within acc.
    By default, acc is epsilon().

    The hyperbolic tangent is calculated using the formula:

	tanh(x) = sinh(x) / cosh(x)

EXAMPLE
    > print tanh(-1), tanh(0), tanh(2^-23)
    ~-.76159415595576488811 0 ~.00000011920928955078

    > print tanh(0.4), tanh(0.4, 0.01), tanh(atanh(1-1e-40), 0.001)
    ~.37994896225522488526 ~.37984474241354975299 ~.99999999999999999999

LIMITS
    acc > 0

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

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