jburkardt

WALSH\ Walsh and Haar Transforms {#walsh-walsh-and-haar-transforms align=”center”} =========================

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WALSH is a C++ library which implements versions of the Walsh and Haar transforms.

Note that the programs, as printed in the reference, had a few typographical errors. Several programs, in particular FHT and FRT, could not be made to perform as described in the text, and hence have been omitted.

Licensing: {#licensing align=”center”}

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Languages: {#languages align=”center”}

WALSH is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version and a MATLAB version.

Related Data and Programs: {#related-data-and-programs align=”center”}

HAAR, a C++ library which computes the Haar transform of data.

SFTPACK, a C++ library which implements the “slow” Fourier transform, intended as a teaching tool and comparison with the fast Fourier transform.

SINE_TRANSFORM, a C++ library which demonstrates some simple properties of the discrete sine transform.

Reference: {#reference align=”center”}

1. Ken Beauchamp,\ Walsh functions and their applications,\ Academic Press, 1975,\ ISBN: 0-12-084050-2,\ LC: QA404.5.B33.

Source Code: {#source-code align=”center”}

• walsh.cpp, the source code.
• walsh.hpp, the include file.

Examples and Tests: {#examples-and-tests align=”center”}

• walsh_prb.cpp, a sample calling program.
• walsh_prb_output.txt, the output file.

List of Routines: {#list-of-routines align=”center”}

• FFWT performs an in-place fast Walsh transform.
• FWT performs a fast Walsh transform.
• HAAR performs a Haar transform.
• HAARIN inverts a Haar transform.
• HNORM computes normalization factors for a forward or inverse Haar transform.
• I4_LOG_2 returns the integer part of the logarithm base 2 of an I4.
• I4_MAX returns the maximum of two I4’s.
• I4_MIN returns the minimum of two I4’s.
• I4_MODP returns the nonnegative remainder of I4 division.
• I4_POWER returns the value of I\^J.
• I4_WRAP forces an I4 to lie between given limits by wrapping.
• R8VEC_COPY copies an R8VEC.
• R8VEC_COPY_NEW copies an R8VEC to a “new” R8VEC.
• R8VEC_UNIFORM_01_NEW returns a new unit pseudorandom R8VEC.
• TIMESTAMP prints the current YMDHMS date as a time stamp.
• WALSH performs a fast Walsh transform.

You can go up one level to the C++ source codes.

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Last revised on 16 March 2011.