\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\begin{array}{l}
\mathbf{if}\;x \le -1.693221537821368658447131741849752371853 \cdot 10^{-10}:\\
\;\;\;\;\sqrt{\frac{e^{2 \cdot x} - 1}{\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 r12311 = 2.0;
double r12312 = x;
double r12313 = r12311 * r12312;
double r12314 = exp(r12313);
double r12315 = 1.0;
double r12316 = r12314 - r12315;
double r12317 = exp(r12312);
double r12318 = r12317 - r12315;
double r12319 = r12316 / r12318;
double r12320 = sqrt(r12319);
return r12320;
}
double f(double x) {
double r12321 = x;
double r12322 = -1.6932215378213687e-10;
bool r12323 = r12321 <= r12322;
double r12324 = 2.0;
double r12325 = r12324 * r12321;
double r12326 = exp(r12325);
double r12327 = 1.0;
double r12328 = r12326 - r12327;
double r12329 = -r12327;
double r12330 = r12321 + r12321;
double r12331 = exp(r12330);
double r12332 = fma(r12329, r12327, r12331);
double r12333 = r12328 / r12332;
double r12334 = exp(r12321);
double r12335 = r12334 + r12327;
double r12336 = r12333 * r12335;
double r12337 = sqrt(r12336);
double r12338 = 0.5;
double r12339 = 2.0;
double r12340 = pow(r12321, r12339);
double r12341 = fma(r12327, r12321, r12324);
double r12342 = fma(r12338, r12340, r12341);
double r12343 = sqrt(r12342);
double r12344 = r12323 ? r12337 : r12343;
return r12344;
}



Bits error versus x
if x < -1.6932215378213687e-10Initial program 0.4
rmApplied flip--0.2
Applied associate-/r/0.2
Simplified0.0
if -1.6932215378213687e-10 < x Initial program 36.0
Taylor expanded around 0 6.9
Simplified6.9
Final simplification0.8
herbie shell --seed 2019352 +o rules:numerics
(FPCore (x)
:name "sqrtexp (problem 3.4.4)"
:precision binary64
(sqrt (/ (- (exp (* 2 x)) 1) (- (exp x) 1))))