\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\begin{array}{l}
\mathbf{if}\;x \le -9.47195806647322485446235246220325620925 \cdot 10^{-6}:\\
\;\;\;\;\sqrt{\frac{\mathsf{fma}\left(\sqrt{e^{2 \cdot x}}, e^{\log \left(\sqrt{e^{2 \cdot x}}\right)}, -1\right)}{e^{x} - 1}}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{\mathsf{fma}\left(x, \mathsf{fma}\left(x, 0.5, 1\right), 2\right)}\\
\end{array}double f(double x) {
double r1245065 = 2.0;
double r1245066 = x;
double r1245067 = r1245065 * r1245066;
double r1245068 = exp(r1245067);
double r1245069 = 1.0;
double r1245070 = r1245068 - r1245069;
double r1245071 = exp(r1245066);
double r1245072 = r1245071 - r1245069;
double r1245073 = r1245070 / r1245072;
double r1245074 = sqrt(r1245073);
return r1245074;
}
double f(double x) {
double r1245075 = x;
double r1245076 = -9.471958066473225e-06;
bool r1245077 = r1245075 <= r1245076;
double r1245078 = 2.0;
double r1245079 = r1245078 * r1245075;
double r1245080 = exp(r1245079);
double r1245081 = sqrt(r1245080);
double r1245082 = log(r1245081);
double r1245083 = exp(r1245082);
double r1245084 = 1.0;
double r1245085 = -r1245084;
double r1245086 = fma(r1245081, r1245083, r1245085);
double r1245087 = exp(r1245075);
double r1245088 = r1245087 - r1245084;
double r1245089 = r1245086 / r1245088;
double r1245090 = sqrt(r1245089);
double r1245091 = 0.5;
double r1245092 = fma(r1245075, r1245091, r1245084);
double r1245093 = fma(r1245075, r1245092, r1245078);
double r1245094 = sqrt(r1245093);
double r1245095 = r1245077 ? r1245090 : r1245094;
return r1245095;
}



Bits error versus x
if x < -9.471958066473225e-06Initial program 0.1
rmApplied add-sqr-sqrt0.1
Applied fma-neg0.0
rmApplied add-exp-log0.0
if -9.471958066473225e-06 < x Initial program 34.5
Taylor expanded around 0 6.5
Simplified6.5
Final simplification0.8
herbie shell --seed 2019172 +o rules:numerics
(FPCore (x)
:name "sqrtexp (problem 3.4.4)"
(sqrt (/ (- (exp (* 2.0 x)) 1.0) (- (exp x) 1.0))))