&gt; How is Python even being mentioned as a replacement for Fortran?<p>Its probably being mentioned as such because a lot of the reason people use Fortran is because of key high-performance libraries for particular numeric application domains -- not because Fortran is necessarily the best language, aside from the existence of the those libraries, to express higher-level solutions in those domains. And because Python has convenient wrappers for those libraries, such that where that is the motivation for using Fortran, Python is a reasonable alternative.<p>&gt; Speed issues is the main reason why Python is not more widely used.<p>Sure, and that&#x27;s why you wouldn&#x27;t (with the current implementations available) want to write the low-level numeric routines underlying NumPy in Python.<p>OTOH, once you have NumPy, a lot of time Python makes perfect sense as the language to use for higher-level solutions that rely on the functionality provided by those libraries.