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. To install: perl Install that's all ! or you can still do it the old way ... perl Makefile.PL make make test make install For up-to-date source, see http://www.cpan.org/SITES.html and look for the directory authors/id/P/PJ/PJB Peter J Billam www.pjb.com.au/comp/contact.html www.pjb.com.au