SYNOPSIS
CALL SET99 (trigs, ifax, n)
CALL FAX (ifax, n, 3)
CALL FFTRIG (trigs, n, 3)
DESCRIPTION
trigs - real variable of dimension n
ifax - integer variable of dimension 10
n - the length of the transforms to be performed. n need not be even
but must have prime factors 2, 3 and 5 only. The number of words
of IFAX used increases logarithmically with n. ifax(10) is
sufficient for most practical purposes. (Transforms of length
at least 10000)
SET99 returns in trigs an array of trigonometric function values
subsequently used by FFT routines.
SET99 factorises n into factors of 8,6,5,4,3,2 in ifax (with at most
one factor of 8). ifax(1) contains the number of factors and the factors
themselves are stored in ascending order in IFAX(2),IFAX(3)..
Presence of an illegal factor causes an error message to be written
to unit 6, followed by a RETURN (no abort).
IMPLEMENTATION
These routines are available on both systems : UNICOS and
workstations.
NOTES
FFTRIG and FAX are retained only for compatibility with old versions.
RETURN VALUE
Error message written to unit 6 if illegal factors present.