\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\begin{array}{l}
\mathbf{if}\;x \le -1.288683916673524238328662344654773619368 \cdot 10^{-5}:\\
\;\;\;\;\sqrt{\frac{\mathsf{expm1}\left(\mathsf{log1p}\left(e^{2 \cdot x} - 1\right)\right)}{\frac{e^{x + x} - 1 \cdot 1}{e^{x} + 1}}}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{\mathsf{fma}\left(x, \mathsf{fma}\left(0.5, x, 1\right), 2\right)}\\
\end{array}double f(double x) {
double r27468 = 2.0;
double r27469 = x;
double r27470 = r27468 * r27469;
double r27471 = exp(r27470);
double r27472 = 1.0;
double r27473 = r27471 - r27472;
double r27474 = exp(r27469);
double r27475 = r27474 - r27472;
double r27476 = r27473 / r27475;
double r27477 = sqrt(r27476);
return r27477;
}
double f(double x) {
double r27478 = x;
double r27479 = -1.2886839166735242e-05;
bool r27480 = r27478 <= r27479;
double r27481 = 2.0;
double r27482 = r27481 * r27478;
double r27483 = exp(r27482);
double r27484 = 1.0;
double r27485 = r27483 - r27484;
double r27486 = log1p(r27485);
double r27487 = expm1(r27486);
double r27488 = r27478 + r27478;
double r27489 = exp(r27488);
double r27490 = r27484 * r27484;
double r27491 = r27489 - r27490;
double r27492 = exp(r27478);
double r27493 = r27492 + r27484;
double r27494 = r27491 / r27493;
double r27495 = r27487 / r27494;
double r27496 = sqrt(r27495);
double r27497 = 0.5;
double r27498 = fma(r27497, r27478, r27484);
double r27499 = fma(r27478, r27498, r27481);
double r27500 = sqrt(r27499);
double r27501 = r27480 ? r27496 : r27500;
return r27501;
}



Bits error versus x
if x < -1.2886839166735242e-05Initial program 0.1
rmApplied flip--0.1
Simplified0.0
rmApplied expm1-log1p-u0.0
if -1.2886839166735242e-05 < x Initial program 33.9
Taylor expanded around 0 6.5
Simplified6.5
Final simplification0.9
herbie shell --seed 2019306 +o rules:numerics
(FPCore (x)
:name "sqrtexp (problem 3.4.4)"
:precision binary64
(sqrt (/ (- (exp (* 2 x)) 1) (- (exp x) 1))))