Restrict probably helps. I can't say much about fortran but C still has warts that can significantly impact its math library. For example almost every math func

Restrict probably helps. I can't say much about fortran but C still has warts that can significantly impact its math library. For example almost every math function may set errno, that is a sideeffect that isn't easy to eliminate by the compiler and might bloat the code significantly. For example with gcc a single instruction sqrt turns into a sqrt instruction, followed by several checks to see if it succeeded, followed by a function call to the sqrt library function just to set errno correctly. I just started to disable math-errno completely once I realized that C allows several alternative ways to handle math errors, which basically makes any code relying on it non portable.