4 ms·

and I'm sure pure Fortran would be even faster

• eru 10y ago
  That's mostly because of Fortran doesn't have the same aliasing trouble as C?
  • flamedoge 10y ago
    Pointer indirection is expensive tradeoff for flexibility
• deleted 10y ago
  [deleted]
• alfalfasprout 10y ago
  Eh, doubtful. Sure, it'll be faster than unoptimized C. But when you observe strict aliasing rules in C a modern compiler will generally produce similar quality assembly for both languages. The reason BLAS is so fast is that every single line of code in a hot loop has been hand-optimized and tons of CPU-specific optimizations exist Fortran yields some of the fastest code out of the box, yes, but C/C++ can yield equivalent performance by adhering to certain basic rules.
  • flamedoge 10y ago
    Even with strict aliasing, the only way C/C++ standard effectively lets one type to be cast to another is incurring a copy. Tell me what can be done better for performance in C that can't be done in Fortran or "another static language without pointer indirection".