\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\begin{array}{l}
\mathbf{if}\;x \le -2.163484807190271 \cdot 10^{-7}:\\
\;\;\;\;\sqrt{\frac{e^{2 \cdot x} - 1}{\mathsf{fma}\left(-1, 1, e^{x + x}\right)} \cdot \mathsf{fma}\left(\sqrt{e^{x}}, \sqrt{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 r11839 = 2.0;
double r11840 = x;
double r11841 = r11839 * r11840;
double r11842 = exp(r11841);
double r11843 = 1.0;
double r11844 = r11842 - r11843;
double r11845 = exp(r11840);
double r11846 = r11845 - r11843;
double r11847 = r11844 / r11846;
double r11848 = sqrt(r11847);
return r11848;
}
double f(double x) {
double r11849 = x;
double r11850 = -2.163484807190271e-07;
bool r11851 = r11849 <= r11850;
double r11852 = 2.0;
double r11853 = r11852 * r11849;
double r11854 = exp(r11853);
double r11855 = 1.0;
double r11856 = r11854 - r11855;
double r11857 = -r11855;
double r11858 = r11849 + r11849;
double r11859 = exp(r11858);
double r11860 = fma(r11857, r11855, r11859);
double r11861 = r11856 / r11860;
double r11862 = exp(r11849);
double r11863 = sqrt(r11862);
double r11864 = fma(r11863, r11863, r11855);
double r11865 = r11861 * r11864;
double r11866 = sqrt(r11865);
double r11867 = 0.5;
double r11868 = 2.0;
double r11869 = pow(r11849, r11868);
double r11870 = fma(r11855, r11849, r11852);
double r11871 = fma(r11867, r11869, r11870);
double r11872 = sqrt(r11871);
double r11873 = r11851 ? r11866 : r11872;
return r11873;
}



Bits error versus x
if x < -2.163484807190271e-07Initial program 0.2
rmApplied flip--0.1
Applied associate-/r/0.1
Simplified0.0
rmApplied add-sqr-sqrt0.0
Applied fma-def0.0
if -2.163484807190271e-07 < x Initial program 35.2
Taylor expanded around 0 6.7
Simplified6.7
Final simplification0.8
herbie shell --seed 2020083 +o rules:numerics
(FPCore (x)
:name "sqrtexp (problem 3.4.4)"
:precision binary64
(sqrt (/ (- (exp (* 2 x)) 1) (- (exp x) 1))))