myxcorr(a,b)

function c = myxcorr(a,b)
%MYXCORR FFT accelerated cross-correlation function estimates.
%   If A is a N x NA matrix and B is N x NB matrix
%   C is a NA+NB-1 matix
%
%   If A is a N x NA matrix, then MYXCORR(A) is the auto-correlation
%   sequence.   
%
%   See also CONV, CONV2, XCORR, MYCONV, MYCONV2, MYXCORR2
%
%   clear all;
% 
%   %  Create a "measurement" domain
%   Lx = 1e-3;
%   Nx = 2^15;
%   x  = Lx*(0:Nx-1)/Nx;
%   dx = x(2)-x(1);
% 
%   % "Sample" the (periodic) signal
%   z = cos(2*pi*2*x/Lx)+...
%       0.5*cos(2*pi*5*(x-0.14*Lx)/Lx)+...
%       0.25*cos(2*pi*20*(x-0.3*Lx)/Lx)+...
%       0.25*cos(2*pi*30*(x-0.7*Lx)/Lx);
%
%   Nz = length(z);
% 
%   % Filter weighting function
%   lcx = Lx/5; % Cut-off acc to ISO 11562 Gaussian Profile Filter Lx/5
%   xf  = [x x(end)+dx]-Lx/2; % Symmetric and ensure that Nx+Nh-1 = 2^k
%   variancex = 1/(pi*sqrt(2/log(2)))*lcx;
%   h = dx/(sqrt(2*pi)*variancex)*...
%   exp(-(((xf)/variancex).^2)/2);
%   Nh  = length(h);
% 
%   % Total length of the padded arrays needed for the fft operations
%   N  = Nz+Nh-1;
%
%   % Cross correlation - built in function
%   tic;
%   xc = xcorr(z,z);
%   toc;
% 
%   % Cross correlation - my fft accelerated version
%   tic;
%   xf = myxcorr(z,z);
%   toc;
% 
%   % Plotting the results
%   plot(...
%     1:N-1, xc(1,:)    , 'k.' ,...Filtered - spatial domain
%     1:N-1, xf(1,:)    , 'r--'...Filtered - freq. domain
%     );

%   Author(s): A. Almqvist
%   Copyright 2009- Andreas Almqvist
%   $Revision: 1$  $Date: 2009/11$
%   Homemade function

if nargin == 1
	b = a;
end
c = myconv(a,rot90(conj(b),2));