[libcxx-commits] [PATCH] D60371: Add lerp function to cmath (P0811R3)

[Marshall Clow via Phabricator via libcxx-commits]

mclow.lists added a comment.

The paper suggests an implementation like this:

  constexpr Float lerp(Float a, Float b, Float t) {
    // Exact, monotonic, bounded, determinate, and (for a=b=0) consistent:
    if(a<=0 && b>=0 || a>=0 && b<=0) return t*b + (1-t)*a;
  
    if(t==1) return b;                        // exact
    // Exact at t=0, monotonic except near t=1,
    // bounded, determinate, and consistent:
    const Float x = a + t*(b-a);
    return t>1 == b>a ? max(b,x) : min(b,x);  // monotonic near t=1
  }

I've tested this, and it works "pretty well", but not (I think) well enough.


Repository:
  rCXX libc++

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  https://reviews.llvm.org/D60371/new/

https://reviews.llvm.org/D60371