• Bazebara
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    21 month ago

    Nice article, I enjoyed it. Why float sqrt has been used? Integer sqrt is way faster and easily supports integers of any lengths

      • Bazebara
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        11 month ago

        Algorithm is so plain and simple, it doesn’t require nightly or Rust specifically to implement.

        • @[email protected]OP
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          1 month ago

          Well, yeah, but you asked why they didn’t use integer sqrt. It’s something many programming languages just don’t have. Or if they do, it’s internally implemented as a sqrt(f64) anyway, like C++ does.

          Most CPUs AFAIK don’t have integer sqrt instructions so you either do it manually in some kind of loop, or you use floating point…

          • Bazebara
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            11 month ago

            Integer sqrt is usually not a library function and it’s very easy to implement, just a few lines of code. Algorithm is well defined on Wikipedia you read a lot. And yes, it doesn’t use FPU at all and it’s quite fast even on i8086.

            • @[email protected]OP
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              11 month ago

              I doubt doing it in software like that outperforms sqrtss/sqrtsd. Modern CPUs can do the conversions and the floating point sqrt in approximately 20-30 cycles total. That’s comparable to one integer division. But I wouldn’t mind being proven wrong.

              • Bazebara
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                21 month ago

                Integer sqrt can be used for integers with any length, not only for integers fit into f64