Removing underflow errors and zero division.

[mirkoklukas]

I fixed the warnings and errors that occur when computing the predictions:

• one was caused because an interval over which a function is evaluated was not set right. the function would evaluate to zero over the set range. I re-centered the interval correctly.
• scipy.stats's skewnorm throughs an underflow error, which doesn't really seem to be an issue: the resulting function seems fine. I am now telling numpy to ignore these errors and only raise a warning.