[alexey-salmin]

People who do HPC in C actually wish C had proper arrays like Fortran. If your function takes two pointers as inputs instead of two arrays they can alias the same memory and in fact they may alias any other pointer of the same type. Writing into one of them invalidates all the values you have in registers so you have to load them again.

The "restrict" keyword was invented to solve this but it still has weaker semantics than original Fortran arrays. It can still solve a big share of problems, but it never got proper adoption and never even made it into C++.

[xmcqdpt2]

Sometimes you have to use C but really they should be doing HPC in fortran. It has C FFI, it can compile to static programs and to dynamic libraries, it has C-like performance, etc.

(It's not as portable as C though, and the compilers have more bugs.)