\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\begin{array}{l}
\mathbf{if}\;x \le -3.608732958076172508184858989110921356769 \cdot 10^{-5} \lor \neg \left(x \le 1.324600673656064518905561606948045724394 \cdot 10^{-14}\right):\\
\;\;\;\;\sqrt{\frac{\sqrt[3]{{\left(\sqrt{e^{2 \cdot x}} + \sqrt{1}\right)}^{3}}}{\frac{e^{x} - 1}{\sqrt{e^{2 \cdot x}} - \sqrt{1}}}}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{x \cdot \left(1 + 0.5 \cdot x\right) + 2}\\
\end{array}double f(double x) {
double r39248 = 2.0;
double r39249 = x;
double r39250 = r39248 * r39249;
double r39251 = exp(r39250);
double r39252 = 1.0;
double r39253 = r39251 - r39252;
double r39254 = exp(r39249);
double r39255 = r39254 - r39252;
double r39256 = r39253 / r39255;
double r39257 = sqrt(r39256);
return r39257;
}
double f(double x) {
double r39258 = x;
double r39259 = -3.6087329580761725e-05;
bool r39260 = r39258 <= r39259;
double r39261 = 1.3246006736560645e-14;
bool r39262 = r39258 <= r39261;
double r39263 = !r39262;
bool r39264 = r39260 || r39263;
double r39265 = 2.0;
double r39266 = r39265 * r39258;
double r39267 = exp(r39266);
double r39268 = sqrt(r39267);
double r39269 = 1.0;
double r39270 = sqrt(r39269);
double r39271 = r39268 + r39270;
double r39272 = 3.0;
double r39273 = pow(r39271, r39272);
double r39274 = cbrt(r39273);
double r39275 = exp(r39258);
double r39276 = r39275 - r39269;
double r39277 = r39268 - r39270;
double r39278 = r39276 / r39277;
double r39279 = r39274 / r39278;
double r39280 = sqrt(r39279);
double r39281 = 0.5;
double r39282 = r39281 * r39258;
double r39283 = r39269 + r39282;
double r39284 = r39258 * r39283;
double r39285 = r39284 + r39265;
double r39286 = sqrt(r39285);
double r39287 = r39264 ? r39280 : r39286;
return r39287;
}



Bits error versus x
Results
if x < -3.6087329580761725e-05 or 1.3246006736560645e-14 < x Initial program 0.8
rmApplied add-sqr-sqrt0.8
Applied add-sqr-sqrt0.8
Applied difference-of-squares0.3
Applied associate-/l*0.3
rmApplied add-cbrt-cube0.4
Simplified0.4
if -3.6087329580761725e-05 < x < 1.3246006736560645e-14Initial program 45.2
Taylor expanded around 0 0.1
Simplified0.1
Final simplification0.4
herbie shell --seed 2019318
(FPCore (x)
:name "sqrtexp (problem 3.4.4)"
:precision binary64
(sqrt (/ (- (exp (* 2 x)) 1) (- (exp x) 1))))