scikit-learn/scikit-learn — pull request #1353 by dengemann (2012-11-10 18:47:20+00:00)
Title: FIX + ENH: catch custom function argument errors and inform user

- added expception in case a user passes a non-tuple returning function and does not supply the derrivatives via fun_prime
- added an example on the custom function type expected to the docs
- added regression tests and positive tests