\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\begin{array}{l}
\mathbf{if}\;x \le -1.3921498547628525 \cdot 10^{-5}:\\
\;\;\;\;\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 r65 = 2.0;
double r66 = x;
double r67 = r65 * r66;
double r68 = exp(r67);
double r69 = 1.0;
double r70 = r68 - r69;
double r71 = exp(r66);
double r72 = r71 - r69;
double r73 = r70 / r72;
double r74 = sqrt(r73);
return r74;
}
double f(double x) {
double r75 = x;
double r76 = -1.3921498547628525e-05;
bool r77 = r75 <= r76;
double r78 = 2.0;
double r79 = r78 * r75;
double r80 = exp(r79);
double r81 = 1.0;
double r82 = r80 - r81;
double r83 = -r81;
double r84 = r75 + r75;
double r85 = exp(r84);
double r86 = fma(r83, r81, r85);
double r87 = r82 / r86;
double r88 = exp(r75);
double r89 = r88 + r81;
double r90 = r87 * r89;
double r91 = sqrt(r90);
double r92 = 0.5;
double r93 = 2.0;
double r94 = pow(r75, r93);
double r95 = fma(r81, r75, r78);
double r96 = fma(r92, r94, r95);
double r97 = sqrt(r96);
double r98 = r77 ? r91 : r97;
return r98;
}



Bits error versus x
if x < -1.3921498547628525e-05Initial program 0.1
rmApplied flip--0.0
Applied associate-/r/0.0
Simplified0.0
if -1.3921498547628525e-05 < x Initial program 34.0
Taylor expanded around 0 6.0
Simplified6.0
Final simplification0.8
herbie shell --seed 2020025 +o rules:numerics
(FPCore (x)
:name "sqrtexp (problem 3.4.4)"
:precision binary64
(sqrt (/ (- (exp (* 2 x)) 1) (- (exp x) 1))))