As a simple example : once upon a time a
We needed to generate a sort of heat map.
Doing it in pure python takes a few seconds at the desired size (few thousand cells where each cell needs a small formula). Dropping to numpy braucht that downs to hundreds of milliseconds. Pushing it to pure c got us to tens of milliseconds.
Yeah one of other beauties of numpy is you can pass data to/from native shared libraries compiled from C code with little overhead. This was more klidgy in Matlab last I checked
