annotate toolboxes/distance_learning/mlr/distance/setDistanceFull.m @ 0:e9a9cd732c1e tip

first hg version after svn
author wolffd
date Tue, 10 Feb 2015 15:05:51 +0000
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wolffd@0 1 function D = setDistanceFull(X, W, Ifrom, Ito)
wolffd@0 2 %
wolffd@0 3 % D = setDistanceFull(X, W, Ifrom, Ito)
wolffd@0 4 %
wolffd@0 5 % X = d-by-n data matrix
wolffd@0 6 % W = d-by-d PSD matrix
wolffd@0 7 % Ifrom = k-by-1 vector of source points
wolffd@0 8 % Ito = j-by-1 vector of destination points
wolffd@0 9 %
wolffd@0 10 % D = n-by-n matrix of squared euclidean distances from Ifrom to Ito
wolffd@0 11 % D is sparse, and only the rows corresponding to Ifrom and
wolffd@0 12 % columns corresponding to Ito are populated.
wolffd@0 13
wolffd@0 14 [d,n] = size(X);
wolffd@0 15 [vecs,vals] = eig(0.5 * (W + W'));
wolffd@0 16 L = real(abs(vals)).^0.5 * vecs';
wolffd@0 17
wolffd@0 18 Vfrom = L * X(:,Ifrom);
wolffd@0 19
wolffd@0 20 if nargin == 4
wolffd@0 21 Vto = L * X(:,Ito);
wolffd@0 22 else
wolffd@0 23 Vto = L * X;
wolffd@0 24 Ito = 1:n;
wolffd@0 25 end
wolffd@0 26
wolffd@0 27 D = distToFrom(n, Vto, Vfrom, Ito, Ifrom);
wolffd@0 28 end