For better or worse, Fortran is still a popular language to write clever PDE schemes in, as it maximizes "time to first, fast-enough-running code".
But for anything with a userbase of more than ~15 people, C/C++ are widely preferred.
But for anything with a userbase of more than ~15 people, C/C++ are widely preferred.
First time I saw this claim was over 9 years ago.