View source for Ted Schnittgen ECE301 Summer2009 - Rhea

function [ y ] = convolution2( h, x )

%CONVOLUTION computes the convolution for two DT LTI signals
%   y = convolution2(h,x) convolves vectors h and x.
%       Algebraically, convolution is the same operation as multiplying the
%       polynomials whose coefficients are the elements of h and x.
%       For more information, refer to the built in convolution command
%       (conv)

nh = numel(h);
nx = numel(x);
nv = nh + nx - 1;

r = h.' * x;
b = zeros(nv,nh);

c = arrayfun(@(x)(x-1)*nv+(x:x+nx-1),1:nh,'uni',false);
c = cat(1,c{:});

b(c) = r;
r = sum(b.');

y = r;


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function [ y ] = convolution3( h, x )

%CONVOLUTION computes the convolution for two DT LTI signals
%   y = convolution(h,x) convolves vectors h and x.
%       Algebraically, convolution is the same operation as multiplying the
%       polynomials whose coefficients are the elements of h and x.
%       For more information, refer to the built in convolution command
%       (conv)


X = fft([x zeros(1,length(h)-1)]);
H = fft([h zeros(1,length(x)-1)]);

y = ifft(X.*H);