HP MLIB User's Guide Vol. 2 7th Ed.

558 HP MLIB User’s Guide
CFFTS/ZFFTS Simultaneous one-dimensional FFT
ier = −2 incl ≤ 0.
ier
= −3 n ≤ 0.
ier
= −4 incn ≤ 0.
ier = −5 l, incl, n, and incn are incompatible.
Refer to “Notes.”
Notes Typically, z will be a two- or three-dimensional array with each set of data
being a one-dimensional section of the array, that is, all but one subscript will
be constant within a data set.
If z is a two-dimensional array of dimension ldz by mdz, and if the data sets are
stored in the columns of z, l ≤ ldz, n ≤ mdz, incl = 1, and incn = ldz. For
example,
CALL CFFTS (z, l, 1, n, ldz, iopt, ier)
If z is a two-dimensional array as above and data sets are stored in rows of z,
l ≤ mdz, n ≤ ldz, incl = ldz, and incn = 1. For example,
CALL CFFTS (z, l, ldz, n, 1, iopt, ier)
If z is a three-dimensional array of dimension ldz by mdz by ndz, then incl and
incn will usually be 1, ldz, or ldz × mdz, depending on which of the subscripts of
the three-dimensional array varies within a data set, which subscript varies
between data sets, and which remains constant. Specifically, if the subscript
that varies within a data set is the
Similarly, if the subscript that varies between data sets is the
l, incl, n, and incn must be such that no two points of any data sets occupy the
same element of z. These subprograms detect this situation and return ier = −5
if
and
where is the greatest common divisor.
1st subscript, use incl = 1.
2nd subscript, use incl = ldz.
3rd subscript, use incl = ldz × mdz.
1st subscript, use incn = 1.
2nd subscript, use incn = ldz.
3rd subscript, use incn = ldz × mdz.
incl n< gcd incl incn,()×
incn l< gcd incl incn,()×
gcd(.,.)