NAME
RadTrans_planckInt
SYNOPSIS
call RadTrans_planckInt(real(IN) :: x,
real(OUT) :: p)
DESCRIPTION
This routine must evaluate the Planck integral
The Planck integral is:
x/| y^3
P(x) = | dy ----------
0 |/ exp(y) - 1
ARGUMENTS
x : The argument for the planck integral p : The value of the integral