muricoca/crab — pull request #74 by alexlin88 (2012-01-16 05:57:47+00:00)
Title: Bugfix for SVD Recommender SGD and RMSE calculation

1. fix partial derivatives of user factor. delta_u = err * i_f - self.regularization * u_f
2. current rmse formula is sum(error)**2 / num. of training instances
It should be RMSE = sum(error ** 2) / num. of training instances.

Thanks