Average Error: 30.5 → 0.0
Time: 11.3s
Precision: 64
\[\frac{1 - \cos x}{\sin x}\]
↓
\[\tan \left(\frac{x}{2}\right)\]
\frac{1 - \cos x}{\sin x}
↓
\tan \left(\frac{x}{2}\right)
double f(double x) {
        double r752351 = 1.0;
        double r752352 = x;
        double r752353 = cos(r752352);
        double r752354 = r752351 - r752353;
        double r752355 = sin(r752352);
        double r752356 = r752354 / r752355;
        return r752356;
}
↓
double f(double x) {
        double r752357 = x;
        double r752358 = 2.0;
        double r752359 = r752357 / r752358;
        double r752360 = tan(r752359);
        return r752360;
}

Error

Bits error versus x

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Results

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Target

Original30.5
Target0.0
Herbie0.0
\[\tan \left(\frac{x}{2}\right)\]

Derivation

  1. Initial program 30.5

    \[\frac{1 - \cos x}{\sin x}\]

  2. Simplified0.0

    \[\leadsto \color{blue}{\tan \left(\frac{x}{2}\right)}\]

  3. Final simplification0.0

    \[\leadsto \tan \left(\frac{x}{2}\right)\]

Reproduce

herbie shell --seed 2019128 +o rules:numerics
(FPCore (x)
  :name "tanhf (example 3.4)"
  :herbie-expected 2

  :herbie-target
  (tan (/ x 2))

  (/ (- 1 (cos x)) (sin x)))