PDA_CFFTI - Initialize PDA_CFFTF and PDA_CFFTB.

Origin

FFTPACK / NETLIB

Implementation Status:

A double precision version PDA_DCFFTI of the routine has been added.

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subroutine pda_cffti(n,wsave)

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subroutine pda_cffti initializes the array wsave which is used in
both pda_cfftf and pda_cfftb. the prime factorization of n together with
a tabulation of the trigonometric functions are computed and
stored in wsave.

input parameter

n       the length of the sequence to be transformed

output parameter

wsave   a work array which must be dimensioned at least 4*n+15
        the same work array can be used for both pda_cfftf and pda_cfftb
        as long as n remains unchanged. different wsave arrays
        are required for different values of n. the contents of
        wsave must not be changed between calls of pda_cfftf or pda_cfftb.