Average Error: 30.1 → 0.0
Time: 10.7s
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 r2578308 = 1.0;
        double r2578309 = x;
        double r2578310 = cos(r2578309);
        double r2578311 = r2578308 - r2578310;
        double r2578312 = sin(r2578309);
        double r2578313 = r2578311 / r2578312;
        return r2578313;
}
↓
double f(double x) {
        double r2578314 = x;
        double r2578315 = 2.0;
        double r2578316 = r2578314 / r2578315;
        double r2578317 = tan(r2578316);
        return r2578317;
}

Error

Bits error versus x

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Results

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Target

Original30.1
Target0.0
Herbie0.0
\[\tan \left(\frac{x}{2}\right)\]

Derivation

  1. Initial program 30.1

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

  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 2019104 +o rules:numerics
(FPCore (x)
  :name "tanhf (example 3.4)"
  :herbie-expected 2

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

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