matplotlib/matplotlib — pull request #2428 by cpelley (2013-09-17 13:38:50+00:00)
Title: BUG: Fixed object type missmatch in SymLogNorm

Currently SymLogNorm accepts both linthresh and vmin, vmax with their
native dtype, meaning that the contents of one object cannot be updated
with another due to a mismatch of types.

`a[masked] = log` within `_transform` and `_inv_transform` requires both to be of the same type for such an operation.