Homebrew/homebrew-science — pull request #1374 by macrael (2014-11-19 19:21:01+00:00)
Title: Add mlpack dependency on hdf5

brew install mlpack failed because my machine did not have hdf5 installed. By running brew install hdf5 I was able to get brew install mlpack to work. I believe this is the correct way to add that dependency to the recipe but I am just guessing really.