comparison toolboxes/FullBNT-1.0.7/netlab3.3/dist2.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function n2 = dist2(x, c)
+%DIST2	Calculates squared distance between two sets of points.
+%
+%	Description
+%	D = DIST2(X, C) takes two matrices of vectors and calculates the
+%	squared Euclidean distance between them.  Both matrices must be of
+%	the same column dimension.  If X has M rows and N columns, and C has
+%	L rows and N columns, then the result has M rows and L columns.  The
+%	I, Jth entry is the  squared distance from the Ith row of X to the
+%	Jth row of C.
+%
+%	See also
+%	GMMACTIV, KMEANS, RBFFWD
+%
+
+%	Copyright (c) Ian T Nabney (1996-2001)
+
+[ndata, dimx] = size(x);
+[ncentres, dimc] = size(c);
+if dimx ~= dimc
+	error('Data dimension does not match dimension of centres')
+end
+
+n2 = (ones(ncentres, 1) * sum((x.^2)', 1))' + ...
+  ones(ndata, 1) * sum((c.^2)',1) - ...
+  2.*(x*(c'));
+
+% Rounding errors occasionally cause negative entries in n2
+if any(any(n2<0))
+  n2(n2<0) = 0;
+end