Average Error: 0.0 → 0.0
Time: 771.0ms
Precision: 64
\[\left(x \cdot y + x\right) + y\]
↓
\[\mathsf{fma}\left(x + 1, y, x\right)\]
\left(x \cdot y + x\right) + y
↓
\mathsf{fma}\left(x + 1, y, x\right)
double f(double x, double y) {
        double r108602 = x;
        double r108603 = y;
        double r108604 = r108602 * r108603;
        double r108605 = r108604 + r108602;
        double r108606 = r108605 + r108603;
        return r108606;
}
↓
double f(double x, double y) {
        double r108607 = x;
        double r108608 = 1.0;
        double r108609 = r108607 + r108608;
        double r108610 = y;
        double r108611 = fma(r108609, r108610, r108607);
        return r108611;
}

Error

Bits error versus x

Bits error versus y

Derivation

  1. Initial program 0.0

    \[\left(x \cdot y + x\right) + y\]

  2. Simplified0.0

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

  3. Taylor expanded around 0 0.0

    \[\leadsto \color{blue}{x + \left(y + x \cdot y\right)}\]

  4. Simplified0.0

    \[\leadsto \color{blue}{\mathsf{fma}\left(x + 1, y, x\right)}\]

  5. Final simplification0.0

    \[\leadsto \mathsf{fma}\left(x + 1, y, x\right)\]

Reproduce

herbie shell --seed 2020025 +o rules:numerics
(FPCore (x y)
  :name "Numeric.Log:$cexpm1 from log-domain-0.10.2.1, B"
  :precision binary64
  (+ (+ (* x y) x) y))