Average Error: 58.6 → 0.6
Time: 16.1s
Precision: 64
\[\log \left(\frac{1 - \varepsilon}{1 + \varepsilon}\right)\]
↓
\[2 \cdot \left(\varepsilon \cdot \varepsilon - \left(\varepsilon + \frac{\varepsilon \cdot \varepsilon}{1 \cdot 1}\right)\right) + \log 1\]
\log \left(\frac{1 - \varepsilon}{1 + \varepsilon}\right)
↓
2 \cdot \left(\varepsilon \cdot \varepsilon - \left(\varepsilon + \frac{\varepsilon \cdot \varepsilon}{1 \cdot 1}\right)\right) + \log 1
double f(double eps) {
        double r3721092 = 1.0;
        double r3721093 = eps;
        double r3721094 = r3721092 - r3721093;
        double r3721095 = r3721092 + r3721093;
        double r3721096 = r3721094 / r3721095;
        double r3721097 = log(r3721096);
        return r3721097;
}
↓
double f(double eps) {
        double r3721098 = 2.0;
        double r3721099 = eps;
        double r3721100 = r3721099 * r3721099;
        double r3721101 = 1.0;
        double r3721102 = r3721101 * r3721101;
        double r3721103 = r3721100 / r3721102;
        double r3721104 = r3721099 + r3721103;
        double r3721105 = r3721100 - r3721104;
        double r3721106 = r3721098 * r3721105;
        double r3721107 = log(r3721101);
        double r3721108 = r3721106 + r3721107;
        return r3721108;
}

Error

Bits error versus eps

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Target

Original58.6
Target0.2
Herbie0.6
\[-2 \cdot \left(\left(\varepsilon + \frac{{\varepsilon}^{3}}{3}\right) + \frac{{\varepsilon}^{5}}{5}\right)\]

Derivation

  1. Initial program 58.6

    \[\log \left(\frac{1 - \varepsilon}{1 + \varepsilon}\right)\]

  2. Taylor expanded around 0 0.6

    \[\leadsto \color{blue}{\left(\log 1 + 2 \cdot {\varepsilon}^{2}\right) - \left(2 \cdot \frac{{\varepsilon}^{2}}{{1}^{2}} + 2 \cdot \varepsilon\right)}\]

  3. Simplified0.6

    \[\leadsto \color{blue}{\log 1 + 2 \cdot \left(\varepsilon \cdot \varepsilon - \left(\varepsilon + \frac{\varepsilon \cdot \varepsilon}{1 \cdot 1}\right)\right)}\]

  4. Final simplification0.6

    \[\leadsto 2 \cdot \left(\varepsilon \cdot \varepsilon - \left(\varepsilon + \frac{\varepsilon \cdot \varepsilon}{1 \cdot 1}\right)\right) + \log 1\]

Reproduce

herbie shell --seed 2019192 
(FPCore (eps)
  :name "logq (problem 3.4.3)"

  :herbie-target
  (* -2.0 (+ (+ eps (/ (pow eps 3.0) 3.0)) (/ (pow eps 5.0) 5.0)))

  (log (/ (- 1.0 eps) (+ 1.0 eps))))