Average Error: 0.0 → 0.0
Time: 1.0s
Precision: 64
\[0.5 \cdot \left(x \cdot x - y\right)\]
↓
\[0.5 \cdot \mathsf{fma}\left(x, x, -y\right)\]
0.5 \cdot \left(x \cdot x - y\right)
↓
0.5 \cdot \mathsf{fma}\left(x, x, -y\right)
double f(double x, double y) {
        double r507 = 0.5;
        double r508 = x;
        double r509 = r508 * r508;
        double r510 = y;
        double r511 = r509 - r510;
        double r512 = r507 * r511;
        return r512;
}
↓
double f(double x, double y) {
        double r513 = 0.5;
        double r514 = x;
        double r515 = y;
        double r516 = -r515;
        double r517 = fma(r514, r514, r516);
        double r518 = r513 * r517;
        return r518;
}

Error

Bits error versus x

Bits error versus y

Derivation

  1. Initial program 0.0

    \[0.5 \cdot \left(x \cdot x - y\right)\]
  2. Using strategy rm

  3. Applied fma-neg0.0

    \[\leadsto 0.5 \cdot \color{blue}{\mathsf{fma}\left(x, x, -y\right)}\]

  4. Final simplification0.0

    \[\leadsto 0.5 \cdot \mathsf{fma}\left(x, x, -y\right)\]

Reproduce

herbie shell --seed 2020033 +o rules:numerics
(FPCore (x y)
  :name "System.Random.MWC.Distributions:standard from mwc-random-0.13.3.2"
  :precision binary64
  (* 0.5 (- (* x x) y)))