Average Error: 4.2 → 0.8
Time: 6.4s
Precision: 64
\[\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\]
\[\begin{array}{l} \mathbf{if}\;x \le -1.9528378137991099 \cdot 10^{-15}:\\ \;\;\;\;\sqrt{\frac{\left(e^{x} + 1\right) \cdot \left(e^{2 \cdot x} - 1\right)}{e^{2 \cdot x} - 1}}\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \frac{x}{\sqrt{2}} + \left(\sqrt{2} + \frac{{x}^{2}}{\sqrt{2}} \cdot \left(0.25 - \frac{0.125}{2}\right)\right)\\ \end{array}\]
\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}
\begin{array}{l}
\mathbf{if}\;x \le -1.9528378137991099 \cdot 10^{-15}:\\
\;\;\;\;\sqrt{\frac{\left(e^{x} + 1\right) \cdot \left(e^{2 \cdot x} - 1\right)}{e^{2 \cdot x} - 1}}\\

\mathbf{else}:\\
\;\;\;\;0.5 \cdot \frac{x}{\sqrt{2}} + \left(\sqrt{2} + \frac{{x}^{2}}{\sqrt{2}} \cdot \left(0.25 - \frac{0.125}{2}\right)\right)\\

\end{array}
double f(double x) {
        double r19359 = 2.0;
        double r19360 = x;
        double r19361 = r19359 * r19360;
        double r19362 = exp(r19361);
        double r19363 = 1.0;
        double r19364 = r19362 - r19363;
        double r19365 = exp(r19360);
        double r19366 = r19365 - r19363;
        double r19367 = r19364 / r19366;
        double r19368 = sqrt(r19367);
        return r19368;
}

double f(double x) {
        double r19369 = x;
        double r19370 = -1.95283781379911e-15;
        bool r19371 = r19369 <= r19370;
        double r19372 = exp(r19369);
        double r19373 = 1.0;
        double r19374 = r19372 + r19373;
        double r19375 = 2.0;
        double r19376 = r19375 * r19369;
        double r19377 = exp(r19376);
        double r19378 = r19377 - r19373;
        double r19379 = r19374 * r19378;
        double r19380 = 2.0;
        double r19381 = r19380 * r19369;
        double r19382 = exp(r19381);
        double r19383 = r19382 - r19373;
        double r19384 = r19379 / r19383;
        double r19385 = sqrt(r19384);
        double r19386 = 0.5;
        double r19387 = sqrt(r19375);
        double r19388 = r19369 / r19387;
        double r19389 = r19386 * r19388;
        double r19390 = pow(r19369, r19380);
        double r19391 = r19390 / r19387;
        double r19392 = 0.25;
        double r19393 = 0.125;
        double r19394 = r19393 / r19375;
        double r19395 = r19392 - r19394;
        double r19396 = r19391 * r19395;
        double r19397 = r19387 + r19396;
        double r19398 = r19389 + r19397;
        double r19399 = r19371 ? r19385 : r19398;
        return r19399;
}

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 < -1.95283781379911e-15

    1. Initial program 0.7

      \[\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\]
    2. Using strategy rm
    3. Applied flip--0.5

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

      \[\leadsto \sqrt{\frac{e^{2 \cdot x} - 1}{\frac{\color{blue}{\mathsf{fma}\left(-1, 1, e^{x + x}\right)}}{e^{x} + 1}}}\]
    5. Taylor expanded around inf 0.0

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

    if -1.95283781379911e-15 < x

    1. Initial program 37.6

      \[\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\]
    2. Taylor expanded around 0 8.2

      \[\leadsto \color{blue}{\left(0.25 \cdot \frac{{x}^{2}}{\sqrt{2}} + \left(\sqrt{2} + 0.5 \cdot \frac{x}{\sqrt{2}}\right)\right) - 0.125 \cdot \frac{{x}^{2}}{{\left(\sqrt{2}\right)}^{3}}}\]
    3. Simplified8.2

      \[\leadsto \color{blue}{0.5 \cdot \frac{x}{\sqrt{2}} + \left(\sqrt{2} + \frac{{x}^{2}}{\sqrt{2}} \cdot \left(0.25 - \frac{0.125}{2}\right)\right)}\]
  3. Recombined 2 regimes into one program.
  4. Final simplification0.8

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \le -1.9528378137991099 \cdot 10^{-15}:\\ \;\;\;\;\sqrt{\frac{\left(e^{x} + 1\right) \cdot \left(e^{2 \cdot x} - 1\right)}{e^{2 \cdot x} - 1}}\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \frac{x}{\sqrt{2}} + \left(\sqrt{2} + \frac{{x}^{2}}{\sqrt{2}} \cdot \left(0.25 - \frac{0.125}{2}\right)\right)\\ \end{array}\]

Reproduce

herbie shell --seed 2020081 +o rules:numerics
(FPCore (x)
  :name "sqrtexp (problem 3.4.4)"
  :precision binary64
  (sqrt (/ (- (exp (* 2 x)) 1) (- (exp x) 1))))