From fc282045948e014d28d09aaaea5ea21914f94ddb Mon Sep 17 00:00:00 2001 From: neingeist Date: Thu, 27 Nov 2014 23:31:49 +0100 Subject: [PATCH] Collaborative Filtering Cost --- ex8/cofiCostFunc.m | 24 ++++++------------------ 1 file changed, 6 insertions(+), 18 deletions(-) diff --git a/ex8/cofiCostFunc.m b/ex8/cofiCostFunc.m index 00f45ab..37f4bfd 100644 --- a/ex8/cofiCostFunc.m +++ b/ex8/cofiCostFunc.m @@ -11,7 +11,7 @@ X = reshape(params(1:num_movies*num_features), num_movies, num_features); Theta = reshape(params(num_movies*num_features+1:end), ... num_users, num_features); - + % You need to return the following values correctly J = 0; X_grad = zeros(size(X)); @@ -21,7 +21,7 @@ Theta_grad = zeros(size(Theta)); % Instructions: Compute the cost function and gradient for collaborative % filtering. Concretely, you should first implement the cost % function (without regularization) and make sure it is -% matches our costs. After that, you should implement the +% matches our costs. After that, you should implement the % gradient and use the checkCostFunction routine to check % that the gradient is correct. Finally, you should implement % regularization. @@ -29,30 +29,18 @@ Theta_grad = zeros(size(Theta)); % Notes: X - num_movies x num_features matrix of movie features % Theta - num_users x num_features matrix of user features % Y - num_movies x num_users matrix of user ratings of movies -% R - num_movies x num_users matrix, where R(i, j) = 1 if the +% R - num_movies x num_users matrix, where R(i, j) = 1 if the % i-th movie was rated by the j-th user % % You should set the following variables correctly: % -% X_grad - num_movies x num_features matrix, containing the +% X_grad - num_movies x num_features matrix, containing the % partial derivatives w.r.t. to each element of X -% Theta_grad - num_users x num_features matrix, containing the +% Theta_grad - num_users x num_features matrix, containing the % partial derivatives w.r.t. to each element of Theta % - - - - - - - - - - - - - +J = 0.5 * sum(sum(R.*(X*Theta'-Y).^2)); % =============================================================