\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\begin{array}{l}
\mathbf{if}\;x \le -1.31818012348102291 \cdot 10^{-5}:\\
\;\;\;\;\sqrt{\frac{\mathsf{expm1}\left(\mathsf{log1p}\left(e^{2 \cdot x} - 1\right)\right)}{e^{x + x} - 1 \cdot 1}} \cdot \sqrt{\mathsf{expm1}\left(\mathsf{log1p}\left(e^{x} + 1\right)\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 r20074 = 2.0;
double r20075 = x;
double r20076 = r20074 * r20075;
double r20077 = exp(r20076);
double r20078 = 1.0;
double r20079 = r20077 - r20078;
double r20080 = exp(r20075);
double r20081 = r20080 - r20078;
double r20082 = r20079 / r20081;
double r20083 = sqrt(r20082);
return r20083;
}
double f(double x) {
double r20084 = x;
double r20085 = -1.3181801234810229e-05;
bool r20086 = r20084 <= r20085;
double r20087 = 2.0;
double r20088 = r20087 * r20084;
double r20089 = exp(r20088);
double r20090 = 1.0;
double r20091 = r20089 - r20090;
double r20092 = log1p(r20091);
double r20093 = expm1(r20092);
double r20094 = r20084 + r20084;
double r20095 = exp(r20094);
double r20096 = r20090 * r20090;
double r20097 = r20095 - r20096;
double r20098 = r20093 / r20097;
double r20099 = sqrt(r20098);
double r20100 = exp(r20084);
double r20101 = r20100 + r20090;
double r20102 = log1p(r20101);
double r20103 = expm1(r20102);
double r20104 = sqrt(r20103);
double r20105 = r20099 * r20104;
double r20106 = 0.5;
double r20107 = 2.0;
double r20108 = pow(r20084, r20107);
double r20109 = fma(r20090, r20084, r20087);
double r20110 = fma(r20106, r20108, r20109);
double r20111 = sqrt(r20110);
double r20112 = r20086 ? r20105 : r20111;
return r20112;
}



Bits error versus x
if x < -1.3181801234810229e-05Initial program 0.1
rmApplied flip--0.1
Applied associate-/r/0.1
Applied sqrt-prod0.1
Simplified0.0
rmApplied expm1-log1p-u0.0
rmApplied expm1-log1p-u0.0
if -1.3181801234810229e-05 < x Initial program 34.5
Taylor expanded around 0 6.7
Simplified6.7
Final simplification0.9
herbie shell --seed 2020047 +o rules:numerics
(FPCore (x)
:name "sqrtexp (problem 3.4.4)"
:precision binary64
(sqrt (/ (- (exp (* 2 x)) 1) (- (exp x) 1))))