FFTINIT Function (PV-WAVE Extreme Advantage)

Signal Processing Toolkit User Guide > Reference (A to F) > FFTINIT Function (PV-WAVE Extreme Advantage)

Computes the parameters for a one-dimensional FFT to be used in the FFTCOMP Function (PV-WAVE Extreme Advantage) with keyword Init_Params.

Usage

result = FFTINIT(n)

Input Parameters

n—Length of the sequence to be transformed.

Returned Value

result—A one-dimensional array of length 2n + 15.

note	The resulting array can be used in the function FFTCOMP, along with the optional keyword Init_Params.

Keywords

Complex—If present and nonzero, the parameters for a complex transform are computed.

Double—If present and nonzero, double precision is used and the returned array is double precision. This keyword does not have an effect if the initialization is being computed for a complex FFT.

Discussion

FFTINIT should be used when many calls are to be made to the FFTCOMP Function (PV-WAVE Extreme Advantage) without changing the data type of the array and the length of the sequence. The default action of FFTINIT is to compute the parameters necessary for a real FFT. If parameters for a complex FFT are needed, keyword Complex should be specified.

FFTINIT is based on routines in FFTPACK, which was developed by Paul Swarztrauber at the National Center for Atmospheric Research.