function new_m=s_v_recon(m,num_components);
% new_m=s_v_recon(m,num_components)
%  
% Reconstructs matrix m using a lower-dimensional representation
% determined by singular value decomposition.
%
% m:				input matrix (m<n)
% num_components:   dimensionality of output matrix (<m)
%
% new_m:		    new matrix reconstructed from the
%                   principal compnents from the svd of m.

%6/7/96	gmb		Wrote it.

[u,s,v]=svd(m);
scale_facs=ones(size(s,1),1);
scale_facs(num_components+1:size(s,1))= ...
	zeros(1,length(scale_facs)-num_components);

new_s=diag(scale_facs)*s;
new_m=u*new_s*v';