Find prime factors of a given number.
factor, x, p, n
x = Number to factor (>1). in
/QUIET means do not print factors.
/DEBUG Means list steps as they happen.
/TRY Go beyond 20000 primes.
p = Array of prime numbers. out
n = Count of each element of p. out
Note: see also prime, numfactors, print_fact.
R. Sterner. 4 Oct, 1988.
RES 25 Oct, 1990 --- converted to IDL V2.
R. Sterner, 1999 Jun 30 --- Improved (faster, bigger).
R. Sterner, 1999 Jul 7 --- Bigger values (used unsigned).
R. Sterner, 1999 Jul 9 --- Tried to make backward compatable.
R. Sterner, 2000 Jan 06 --- Fixed to ignore non-positive numbers.
Johns Hopkins University Applied Physics Laboratory.
Copyright (C) 1988, Johns Hopkins University/Applied Physics Laboratory
This software may be used, copied, or redistributed as long as it is not
sold and this copyright notice is reproduced on each copy made. This
routine is provided as is without any express or implied warranties
whatsoever. Other limitations apply as described in the file disclaimer.txt.