NAME
    acosh - hyperbolic arc cosine

SYNOPSIS
    acosh(x [,acc])

TYPES
    x		real
    acc		real

    return	real

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

    The hyperbolic arccosine is calculated using the formula:

	acosh(x) = ln(x + sqrt(x^2 - 1))

EXAMPLE
    > print acosh(1), acosh(3^29+1), acosh(3^29+1, 1e-100)
    0 ~32.55290355193514093067 ~32.55290355193514093068

LIMITS
    x >= 1
    acc > 0

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

SEE ALSO
    asinh, atanh, cosh, epsilon, sinh, tanh
