The FACTORIAL function computes the factorial N ! as the double-precision product, ( N ) ( N -1) ( N -2) ... 3 2 1.
This routine is written in the IDL language. Its source code can be found in the file
subdirectory of the IDL distribution.
Note: large values of N will cause floating-point overflow errors. The maximum size of N varies with machine architecture. On machines that support the IEEE standard for floating-point arithmetic, the maximum value of N is 170. See MACHAR for a discussion of machine-specific parameters affecting floating-point arithmetic.