\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x} - 1}}\begin{array}{l}
\mathbf{if}\;x \le -3.639623849017884427727010081959901910409 \cdot 10^{-7}:\\
\;\;\;\;\sqrt{\frac{e^{2 \cdot x} - 1}{e^{x + x} - 1 \cdot 1} \cdot \frac{{\left(e^{x}\right)}^{3} + {1}^{3}}{1 \cdot \left(1 - e^{x}\right) + e^{2 \cdot x}}}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{2 + x \cdot \left(0.5 \cdot x + 1\right)}\\
\end{array}double f(double x) {
double r20075 = 2.0;
double r20076 = x;
double r20077 = r20075 * r20076;
double r20078 = exp(r20077);
double r20079 = 1.0;
double r20080 = r20078 - r20079;
double r20081 = exp(r20076);
double r20082 = r20081 - r20079;
double r20083 = r20080 / r20082;
double r20084 = sqrt(r20083);
return r20084;
}
double f(double x) {
double r20085 = x;
double r20086 = -3.6396238490178844e-07;
bool r20087 = r20085 <= r20086;
double r20088 = 2.0;
double r20089 = r20088 * r20085;
double r20090 = exp(r20089);
double r20091 = 1.0;
double r20092 = r20090 - r20091;
double r20093 = r20085 + r20085;
double r20094 = exp(r20093);
double r20095 = r20091 * r20091;
double r20096 = r20094 - r20095;
double r20097 = r20092 / r20096;
double r20098 = exp(r20085);
double r20099 = 3.0;
double r20100 = pow(r20098, r20099);
double r20101 = pow(r20091, r20099);
double r20102 = r20100 + r20101;
double r20103 = r20091 - r20098;
double r20104 = r20091 * r20103;
double r20105 = 2.0;
double r20106 = r20105 * r20085;
double r20107 = exp(r20106);
double r20108 = r20104 + r20107;
double r20109 = r20102 / r20108;
double r20110 = r20097 * r20109;
double r20111 = sqrt(r20110);
double r20112 = 0.5;
double r20113 = r20112 * r20085;
double r20114 = r20113 + r20091;
double r20115 = r20085 * r20114;
double r20116 = r20088 + r20115;
double r20117 = sqrt(r20116);
double r20118 = r20087 ? r20111 : r20117;
return r20118;
}



Bits error versus x
Results
if x < -3.6396238490178844e-07Initial program 0.2
rmApplied flip--0.1
Applied associate-/r/0.1
Simplified0.0
rmApplied flip3-+0.0
Simplified0.0
if -3.6396238490178844e-07 < x Initial program 34.4
Taylor expanded around 0 6.6
Simplified6.6
Final simplification0.8
herbie shell --seed 2019325
(FPCore (x)
:name "sqrtexp (problem 3.4.4)"
:precision binary64
(sqrt (/ (- (exp (* 2 x)) 1) (- (exp x) 1))))