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Manuscript Title: UNIDFT: a package of optimized discrete Fourier transforms.
Authors: G. Cabras, V. Roberto, G. Salemi
Program title: UNIDFT
Catalogue identifier: AAXR_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 47(1987)113
Programming language: Fortran.
Computer: VAX 11-780.
Operating system: VMS 4.4.
RAM: 37K words
Word size: 32
Keywords: General purpose, Fourier, Fast fourier transform, Mixed-radix fft, Chirp-zeta transform.
Classification: 4.6.

Nature of problem:
We present a package of FORTRAN 77 subprograms to compute the discrete Fourier transform of one-dimensional data sets. A large collection of specialized modules, assembled in a top-down scheme, guarantees high flexibility and efficiency. Comparative timings are given.

Solution method:
The discrete Fourier transform is computed via mixed-radix Fast Fourier Transform and Chirp-Zeta Transform algorithms, implemented in place, with radix-2,-3,-4,-5 and radix-8 decimation-in-frequency and decimation-in-time basic modules.

Running time:
Top performances are reached for input data lengths which are powers of 8. The CPU-time required by a single-precision complex DFT of 4096 points is roughly 0.66 s; the real DFT on 4096 points requires 0.36 s; typical running times are up to 2 times as much when input data length does not contain powers of 8.