Average Error: 4.5 → 0.7
Time: 18.8s
Precision: 64
\[\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\]
\[\begin{array}{l} \mathbf{if}\;x \le -1.109419166854957547087282512125511104578 \cdot 10^{-10}:\\ \;\;\;\;\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x + x} - 1 \cdot 1}} \cdot \sqrt{e^{x} + 1}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{2 + x \cdot \left(0.5 \cdot x + 1\right)}\\ \end{array}\]
\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}
\begin{array}{l}
\mathbf{if}\;x \le -1.109419166854957547087282512125511104578 \cdot 10^{-10}:\\
\;\;\;\;\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x + x} - 1 \cdot 1}} \cdot \sqrt{e^{x} + 1}\\

\mathbf{else}:\\
\;\;\;\;\sqrt{2 + x \cdot \left(0.5 \cdot x + 1\right)}\\

\end{array}
double f(double x) {
        double r19873 = 2.0;
        double r19874 = x;
        double r19875 = r19873 * r19874;
        double r19876 = exp(r19875);
        double r19877 = 1.0;
        double r19878 = r19876 - r19877;
        double r19879 = exp(r19874);
        double r19880 = r19879 - r19877;
        double r19881 = r19878 / r19880;
        double r19882 = sqrt(r19881);
        return r19882;
}

double f(double x) {
        double r19883 = x;
        double r19884 = -1.1094191668549575e-10;
        bool r19885 = r19883 <= r19884;
        double r19886 = 2.0;
        double r19887 = r19886 * r19883;
        double r19888 = exp(r19887);
        double r19889 = 1.0;
        double r19890 = r19888 - r19889;
        double r19891 = r19883 + r19883;
        double r19892 = exp(r19891);
        double r19893 = r19889 * r19889;
        double r19894 = r19892 - r19893;
        double r19895 = r19890 / r19894;
        double r19896 = sqrt(r19895);
        double r19897 = exp(r19883);
        double r19898 = r19897 + r19889;
        double r19899 = sqrt(r19898);
        double r19900 = r19896 * r19899;
        double r19901 = 0.5;
        double r19902 = r19901 * r19883;
        double r19903 = r19902 + r19889;
        double r19904 = r19883 * r19903;
        double r19905 = r19886 + r19904;
        double r19906 = sqrt(r19905);
        double r19907 = r19885 ? r19900 : r19906;
        return r19907;
}

Error

Bits error versus x

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Derivation

  1. Split input into 2 regimes
  2. if x < -1.1094191668549575e-10

    1. Initial program 0.4

      \[\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\]
    2. Using strategy rm
    3. Applied flip--0.2

      \[\leadsto \sqrt{\frac{e^{2 \cdot x} - 1}{\color{blue}{\frac{e^{x} \cdot e^{x} - 1 \cdot 1}{e^{x} + 1}}}}\]
    4. Applied associate-/r/0.2

      \[\leadsto \sqrt{\color{blue}{\frac{e^{2 \cdot x} - 1}{e^{x} \cdot e^{x} - 1 \cdot 1} \cdot \left(e^{x} + 1\right)}}\]
    5. Applied sqrt-prod0.2

      \[\leadsto \color{blue}{\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} \cdot e^{x} - 1 \cdot 1}} \cdot \sqrt{e^{x} + 1}}\]
    6. Simplified0.0

      \[\leadsto \color{blue}{\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x + x} - 1 \cdot 1}}} \cdot \sqrt{e^{x} + 1}\]

    if -1.1094191668549575e-10 < x

    1. Initial program 36.5

      \[\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\]
    2. Taylor expanded around 0 6.3

      \[\leadsto \sqrt{\color{blue}{0.5 \cdot {x}^{2} + \left(1 \cdot x + 2\right)}}\]
    3. Simplified6.3

      \[\leadsto \sqrt{\color{blue}{2 + x \cdot \left(0.5 \cdot x + 1\right)}}\]
  3. Recombined 2 regimes into one program.
  4. Final simplification0.7

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \le -1.109419166854957547087282512125511104578 \cdot 10^{-10}:\\ \;\;\;\;\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x + x} - 1 \cdot 1}} \cdot \sqrt{e^{x} + 1}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{2 + x \cdot \left(0.5 \cdot x + 1\right)}\\ \end{array}\]

Reproduce

herbie shell --seed 2019212 
(FPCore (x)
  :name "sqrtexp (problem 3.4.4)"
  :precision binary64
  (sqrt (/ (- (exp (* 2 x)) 1) (- (exp x) 1))))