\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\begin{array}{l}
\mathbf{if}\;x \le -4.527236342338421397557006909014021278637 \cdot 10^{-9}:\\
\;\;\;\;\sqrt{\frac{\left(\sqrt{1} + \sqrt{e^{2 \cdot x}}\right) \cdot \left(\sqrt{e^{2 \cdot x}} - \sqrt{1}\right)}{e^{x} - 1}}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{\mathsf{fma}\left(x, \mathsf{fma}\left(0.4999999999999997779553950749686919152737, x, 1\right), 2\right)}\\
\end{array}double f(double x) {
double r1298537 = 2.0;
double r1298538 = x;
double r1298539 = r1298537 * r1298538;
double r1298540 = exp(r1298539);
double r1298541 = 1.0;
double r1298542 = r1298540 - r1298541;
double r1298543 = exp(r1298538);
double r1298544 = r1298543 - r1298541;
double r1298545 = r1298542 / r1298544;
double r1298546 = sqrt(r1298545);
return r1298546;
}
double f(double x) {
double r1298547 = x;
double r1298548 = -4.527236342338421e-09;
bool r1298549 = r1298547 <= r1298548;
double r1298550 = 1.0;
double r1298551 = sqrt(r1298550);
double r1298552 = 2.0;
double r1298553 = r1298552 * r1298547;
double r1298554 = exp(r1298553);
double r1298555 = sqrt(r1298554);
double r1298556 = r1298551 + r1298555;
double r1298557 = r1298555 - r1298551;
double r1298558 = r1298556 * r1298557;
double r1298559 = exp(r1298547);
double r1298560 = r1298559 - r1298550;
double r1298561 = r1298558 / r1298560;
double r1298562 = sqrt(r1298561);
double r1298563 = 0.4999999999999998;
double r1298564 = fma(r1298563, r1298547, r1298550);
double r1298565 = fma(r1298547, r1298564, r1298552);
double r1298566 = sqrt(r1298565);
double r1298567 = r1298549 ? r1298562 : r1298566;
return r1298567;
}



Bits error versus x
if x < -4.527236342338421e-09Initial program 0.3
rmApplied add-sqr-sqrt0.3
Applied add-sqr-sqrt0.3
Applied difference-of-squares0.0
if -4.527236342338421e-09 < x Initial program 34.9
rmApplied add-sqr-sqrt32.2
Applied fma-neg27.5
Taylor expanded around 0 7.5
Simplified7.5
Final simplification0.9
herbie shell --seed 2019168 +o rules:numerics
(FPCore (x)
:name "sqrtexp (problem 3.4.4)"
(sqrt (/ (- (exp (* 2.0 x)) 1.0) (- (exp x) 1.0))))