46 lines
1.3 KiB
Matlab
46 lines
1.3 KiB
Matlab
function d = distance(a,b)
|
|
% DISTANCE - computes Euclidean distance matrix
|
|
%
|
|
% E = distance(A,B)
|
|
%
|
|
% A - (DxM) matrix
|
|
% B - (DxN) matrix
|
|
%
|
|
% Returns:
|
|
% E - (MxN) Euclidean distances between vectors in A and B
|
|
%
|
|
%
|
|
% Description :
|
|
% This fully vectorized (VERY FAST!) m-file computes the
|
|
% Euclidean distance between two vectors by:
|
|
%
|
|
% ||A-B|| = sqrt ( ||A||^2 + ||B||^2 - 2*A.B )
|
|
%
|
|
% Example :
|
|
% A = rand(400,100); B = rand(400,200);
|
|
% d = distance(A,B);
|
|
|
|
% Author : Roland Bunschoten
|
|
% University of Amsterdam
|
|
% Intelligent Autonomous Systems (IAS) group
|
|
% Kruislaan 403 1098 SJ Amsterdam
|
|
% tel.(+31)20-5257524
|
|
% bunschot@wins.uva.nl
|
|
% Last Rev : Oct 29 16:35:48 MET DST 1999
|
|
% Tested : PC Matlab v5.2 and Solaris Matlab v5.3
|
|
% Thanx : Nikos Vlassis
|
|
|
|
% Copyright notice: You are free to modify, extend and distribute
|
|
% this code granted that the author of the original code is
|
|
% mentioned as the original author of the code.
|
|
|
|
if (nargin ~= 2)
|
|
error('Not enough input arguments');
|
|
end
|
|
|
|
if (size(a,1) ~= size(b,1))
|
|
error('A and B should be of same dimensionality');
|
|
end
|
|
|
|
aa=sum(a.*a,1); bb=sum(b.*b,1); ab=a'*b;
|
|
d = sqrt(abs(repmat(aa',[1 size(bb,2)]) + repmat(bb,[size(aa,2) 1]) - 2*ab));
|