I want to contribute (give) two functions to the signal package

[James-Adam Renquinha Henri]

Hello,

I made two functions that allow the design of Legendre-Papoulis filters (see http://www.crbond.com/papers/lopt.pdf). These are

function [z,p,k] = legendap(N)

function [a,b,c,d] = legendf(N, Wp, varargin)

The first gives the zeros, poles and gain of a analog lowpass prototype filter, and the second one acts like the butter function but generating Legendre-Papoulis filters; in fact I literally copied butter.m and edited it to use the legendap function.

Known issues:

- The algorithm to generate the poles in legendap is not numerically stable and efficient; I proceed exactly like in the above pdf and there is an inevitable loss of precision when finding the roots of the polynomial. Using orders of 30 or above yields erratic but stable filters, and that may happen for orders below 30 but I didn't verify this.

- legendap and legendf would require the appropriate test script in the footer.

The functions would be released using the GPL licence.

I want to know if such a contribution is welcome and where would I "svn commit" that code.

―

James-Adam Renquinha Henri