Math::WalshTransform.pm
These routines implement fast Hadamard and Walsh Transforms and their
inverse transforms.
Also included are routines for converting a Hadamard to a Walsh
transform and vice versa, for calculating the Logical Convolution
of two lists, or the Logical Autocorrelation of a list, and for
calculating the Walsh Power Spectrum - in short, almost everything
you ever wanted to do with a Hadamard Transform.
Intelligible speech can be reconstructed by transforming blocks of,
say, 64 samples, deleting all but the several largest transform
components, and inverse-transforming; in other words, these transforms
extract from a time-series the most significant things that are going
on. They should be useful for noticing important things, for example
in software that monitors time-series data such as system or network
administration data, share-price, currency, ecological, opinion poll,
process management data, and so on.
As from version 1.10, Math::WalshTransform uses C routines to perform
the transforms. This runs 25 to 30 times faster than previous versions.
Also included is a call-compatible translation into Lua.
To install:
perl Makefile.PL
make
make test
make install
For up-to-date source, see http://search.cpan.org/~pjb/
Peter J Billam www.pjb.com.au/comp/contact.html www.pjb.com.au