distMat.m

function D=distMat(P1, P2)
%
% Euclidian distances between vectors
% each vector is one row
  
if nargin == 2
    P1 = double(P1);
    P2 = double(P2);
    
    X1=repmat(sum(P1.^2,2),[1 size(P2,1)]);
    X2=repmat(sum(P2.^2,2),[1 size(P1,1)]);
    R=P1*P2';
    D=real(sqrt(X1+X2'-2*R));
else
    P1 = double(P1);

    % each vector is one row
    X1=repmat(sum(P1.^2,2),[1 size(P1,1)]);
    R=P1*P1';
    D=X1+X1'-2*R;
    D = real(sqrt(D));
end