Average Error: 0.0 → 0.0
Time: 10.3s
Precision: 64
\[x.re \cdot y.re - x.im \cdot y.im\]
↓
\[\mathsf{fma}\left(x.re, y.re, -x.im \cdot y.im\right)\]
x.re \cdot y.re - x.im \cdot y.im
↓
\mathsf{fma}\left(x.re, y.re, -x.im \cdot y.im\right)
double f(double x_re, double x_im, double y_re, double y_im) {
        double r2288902 = x_re;
        double r2288903 = y_re;
        double r2288904 = r2288902 * r2288903;
        double r2288905 = x_im;
        double r2288906 = y_im;
        double r2288907 = r2288905 * r2288906;
        double r2288908 = r2288904 - r2288907;
        return r2288908;
}
↓
double f(double x_re, double x_im, double y_re, double y_im) {
        double r2288909 = x_re;
        double r2288910 = y_re;
        double r2288911 = x_im;
        double r2288912 = y_im;
        double r2288913 = r2288911 * r2288912;
        double r2288914 = -r2288913;
        double r2288915 = fma(r2288909, r2288910, r2288914);
        return r2288915;
}

Error

Bits error versus x.re

Bits error versus x.im

Bits error versus y.re

Bits error versus y.im

Derivation

  1. Initial program 0.0

    \[x.re \cdot y.re - x.im \cdot y.im\]
  2. Using strategy rm

  3. Applied fma-neg0.0

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

  4. Final simplification0.0

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

Reproduce

herbie shell --seed 2019172 +o rules:numerics
(FPCore (x.re x.im y.re y.im)
  :name "_multiplyComplex, real part"
  (- (* x.re y.re) (* x.im y.im)))