\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\begin{array}{l}
\mathbf{if}\;x \le -1.1247925004240297 \cdot 10^{-5}:\\
\;\;\;\;\sqrt{\frac{\sqrt[3]{{\left(e^{2 \cdot x} - 1\right)}^{3}}}{\mathsf{fma}\left(-1, 1, e^{x + x}\right)} \cdot \left(e^{x} + 1\right)}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{\mathsf{fma}\left(0.5, {x}^{2}, \mathsf{fma}\left(1, x, 2\right)\right)}\\
\end{array}double f(double x) {
double r11476 = 2.0;
double r11477 = x;
double r11478 = r11476 * r11477;
double r11479 = exp(r11478);
double r11480 = 1.0;
double r11481 = r11479 - r11480;
double r11482 = exp(r11477);
double r11483 = r11482 - r11480;
double r11484 = r11481 / r11483;
double r11485 = sqrt(r11484);
return r11485;
}
double f(double x) {
double r11486 = x;
double r11487 = -1.1247925004240297e-05;
bool r11488 = r11486 <= r11487;
double r11489 = 2.0;
double r11490 = r11489 * r11486;
double r11491 = exp(r11490);
double r11492 = 1.0;
double r11493 = r11491 - r11492;
double r11494 = 3.0;
double r11495 = pow(r11493, r11494);
double r11496 = cbrt(r11495);
double r11497 = -r11492;
double r11498 = r11486 + r11486;
double r11499 = exp(r11498);
double r11500 = fma(r11497, r11492, r11499);
double r11501 = r11496 / r11500;
double r11502 = exp(r11486);
double r11503 = r11502 + r11492;
double r11504 = r11501 * r11503;
double r11505 = sqrt(r11504);
double r11506 = 0.5;
double r11507 = 2.0;
double r11508 = pow(r11486, r11507);
double r11509 = fma(r11492, r11486, r11489);
double r11510 = fma(r11506, r11508, r11509);
double r11511 = sqrt(r11510);
double r11512 = r11488 ? r11505 : r11511;
return r11512;
}



Bits error versus x
if x < -1.1247925004240297e-05Initial program 0.1
rmApplied flip--0.0
Applied associate-/r/0.0
Simplified0.0
rmApplied add-cbrt-cube0.0
Simplified0.0
if -1.1247925004240297e-05 < x Initial program 33.8
Taylor expanded around 0 5.9
Simplified5.9
Final simplification0.8
herbie shell --seed 2020021 +o rules:numerics
(FPCore (x)
:name "sqrtexp (problem 3.4.4)"
:precision binary64
(sqrt (/ (- (exp (* 2 x)) 1) (- (exp x) 1))))