Function numericCostFunction

src/compute-engine/cost-function.ts:47–63

* The Cost Function is used to select the simplest between two expressions: * the one with the lowest cost function. * * It is based on the Mathematica cost function. * * * From https://reference.wolfram.com/language/ref/ComplexityFunction.html * * ``` * SimplifyCount[p_] := * Which[ *

(n: NumericValue | number)

function numericCostFunction(n: NumericValue | number): number {
  if (typeof n === 'number') {
    if (n === 0) return 1;
    if (Number.isInteger(n))
      return (
        Math.floor(Math.log2(Math.abs(n)) / Math.log2(10)) + (n > 0 ? 1 : 2)
      );
    return 2;
  }

  if (n.isZero) return 1;

  if (n.im !== 0) {
    // A pure-imaginary exact value carries its radical in `imRadical`, so it
    // needs the same treatment as the real one below — otherwise `i√17` prices
    // at 4 while `√17` prices at 7, and D6's fix is only half applied.
    const imRad = (n as { imRadical?: number }).imRadical;
    const imExtra =
      imRad !== undefined && imRad > 1 ? 3 + numericCostFunction(imRad) : 0;
    return numericCostFunction(n.re) + numericCostFunction(n.im) + imExtra + 1;
  }