FFT_OPEN_MP
Fast Fourier Transform Using OpenMP

FFT_OPEN_MP is a FORTRAN77 program which demonstrates the computation of a Fast Fourier Transform in parallel, using OpenMP.

On an Apple PowerPC G5 with two processors, the following results were observed:

Threads	N	Time	MegaFLOPS
1	131072	0.094	117.7
2	131072	0.054	203.0
4	131072	0.056	198.8

The relatively low size of N seems to be due to a limitation in the FORTRAN77 compiler.

Usage:

In the BASH shell, the program could be run with 2 threads using the commands:

        export OMP_NUM_THREADS=2
        ./fft_open_mp
      

Related Data and Programs:

FFT_OPEN_MP is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version.

FFT_SERIAL is a FORTRAN77 program which demonstrates the computation of a Fast Fourier Transform, and is intended as a starting point for implementing a parallel version using OpenMP.

MD_OPEN_MP is a FORTRAN77 program which carries out a molecular dynamics simulation using OpenMP.

MXV_OPEN_MP is a FORTRAN77 program which compares the performance of plain vanilla Fortran and the FORTRAN90 intrinsic routine MATMUL, for the matrix multiplication problem y=A*x, with and without parallelization by OpenMP.

OPEN_MP is a directory of FORTRAN77 examples which illustrate the use of the OpenMP application program interface for carrying out parallel computations in a shared memory environment.

OPEN_MP_ITHACA FORTRAN77 programs which illustrate the use of OpenMP on the Virginia Tech ITHACA cluster.

QUAD_OPEN_MP is a FORTRAN77 program which approximates an integral using a quadrature rule, and carries out the computation in parallel using OpenMP.

SATISFIABILITY_OPEN_MP is a FORTRAN77 program which demonstrates, for a particular circuit, an exhaustive search for solutions of the circuit satisfiability problem, using OpenMP for parallel execution.

SGEFA_OPEN_MP is a FORTRAN77 program which solves a linear system by Gaussian elimination, using OpenMP.

ZIGGURAT_OPEN_MP, a FORTRAN77 program which demonstrates how the ZIGGURAT library can be used to generate random numbers in an OpenMP parallel program.

Reference:

1. Wesley Petersen, Peter Arbenz,
   Introduction to Parallel Computing - A practical guide with examples in C,
   Oxford University Press,
   ISBN: 0-19-851576-6,
   LC: QA76.58.P47.
2. Rohit Chandra, Leonardo Dagum, Dave Kohr, Dror Maydan, Jeff McDonald, Ramesh Menon,
   Parallel Programming in OpenMP,
   Morgan Kaufmann, 2001,
   ISBN: 1-55860-671-8,
   LC: QA76.642.P32.
3. Barbara Chapman, Gabriele Jost, Ruud vanderPas, David Kuck,
   Using OpenMP: Portable Shared Memory Parallel Processing,
   MIT Press, 2007,
   ISBN13: 978-0262533027,
   LC: QA76.642.C49.

Source Code:

• fft_open_mp.f, the source code.

Examples and Tests:

FFT_OPEN_MP_RUN runs FFT_OPEN_MP interactively.

• fft_open_mp_run.sh, commands to compile the program and run with 1, 2, 4, and 8 threads.
• fft_open_mp_run_output.txt, the output file using 1, 2, 4 and 8 threads on Virginia Tech's ITHACA cluster.

FFT_OPEN_MP_BATCH runs FFT_OPEN_MP through the batch system.

• fft_open_mp_batch.sh, commands to compile the program and run with 1, 2, 4, and 8 threads.
• fft_open_mp_batch_output.txt, the output file using 1, 2, 4 and 8 threads on Virginia Tech's ITHACA cluster.

List of Routines:

• MAIN is the main program for FFT_OPEN_MP.
• CCOPY copies a complex vector.
• CFFT2 performs a complex Fast Fourier Transform.
• CFFTI sets up sine and cosine tables needed for the FFT calculation.
• GGL generates u(0,1) distributed random numbers.
• STEP carries out one step of the workspace version of CFFT2.
• TIMESTAMP prints the YMDHMS date as a timestamp.

You can go up one level to the FORTRAN77 source codes.