Re: Optimizing a bigint fibonacci

[helxi via Digitalmars-d-learn]

On Wednesday, 6 December 2017 at 10:00:48 UTC, Biotronic wrote:

On Wednesday, 6 December 2017 at 09:12:08 UTC, helxi wrote:

[...]

Here's my version:, based on fast squaring:

auto fib(ulong n) {
    import std.bigint : BigInt;
    import std.meta : AliasSeq;
    import std.typecons : tuple;
    BigInt a = 0;
    BigInt b = 1;
    auto bit = 63;
    while (bit > 0) {
        AliasSeq!(a, b) = tuple(
            a * (2*b - a),
            a*a + b*b);

[...]

Nice. But why the AliasSeq?

That's because the poor compiler isn't as good at optimizing compile-time code as run-time code,

Oh I see. We should definitely be careful with that :D