Functions Menu
==============

     |----+----+----+----+----+----2
     |IGAM|BETA|IBET|ERF |BESJ|BESY|
     |----+----+----+----+----+----|
     |IMAG|CONJ| RE |ATN2|RAND|RAGN|
     |----+----+----+----+----+----|
     |GCD |FACT|DFCT|BNOM|PERM|NXTP|
     |----+----+----+----+----+----|

This menu provides various operations from the `f' and `k' prefix
keys.

IMAG multiplies the number on the stack by the imaginary number `i =
(0, 1)'.

RE extracts the real part a complex number.  `INV RE' extracts the
imaginary part.

RAND takes a number from the top of the stack and computes a random
number greater than or equal to zero but less than that number.
(See Random Numbers.)  RAGN is the "random again" command; it
computes another random number using the same limit as last time.

INV GCD computes the LCM (least common multiple) function.

INV FACT is the gamma function.  `gamma(x) = (x-1)!'.

PERM is the number-of-permutations function, which is on the `H k c'
key in normal Calc.

NXTP finds the next prime after a number.  `INV NXTP' finds the
previous prime.