Cursera: machine learning ex7.

machine_learning/mlclass-ex7-008/mlclass-ex7/recoverData.m

@@ -0,0 +1,29 @@
+function X_rec = recoverData(Z, U, K)
+%RECOVERDATA Recovers an approximation of the original data when using the 
+%projected data
+%   X_rec = RECOVERDATA(Z, U, K) recovers an approximation the 
+%   original data that has been reduced to K dimensions. It returns the
+%   approximate reconstruction in X_rec.
+%
+
+% You need to return the following variables correctly.
+X_rec = zeros(size(Z, 1), size(U, 1));
+
+% ====================== YOUR CODE HERE ======================
+% Instructions: Compute the approximation of the data by projecting back
+%               onto the original space using the top K eigenvectors in U.
+%
+%               For the i-th example Z(i,:), the (approximate)
+%               recovered data for dimension j is given as follows:
+%                    v = Z(i, :)';
+%                    recovered_j = v' * U(j, 1:K)';
+%
+%               Notice that U(j, 1:K) is a row vector.
+%               
+
+X_rec = Z * U(:,1:K)';
+
+
+% =============================================================
+
+end