\frac{x - \sin x}{x - \tan x}\begin{array}{l}
\mathbf{if}\;x \le -0.0320090099806352654:\\
\;\;\;\;\frac{x}{x - \tan x} - \frac{\sin x}{x - \tan x}\\
\mathbf{elif}\;x \le 0.024314219703607573:\\
\;\;\;\;\frac{9}{40} \cdot {x}^{2} - \left(\frac{27}{2800} \cdot {x}^{4} + \frac{1}{2}\right)\\
\mathbf{else}:\\
\;\;\;\;\sqrt[3]{{\left(\frac{x - \sin x}{x - \tan x}\right)}^{3}}\\
\end{array}double f(double x) {
double r12806 = x;
double r12807 = sin(r12806);
double r12808 = r12806 - r12807;
double r12809 = tan(r12806);
double r12810 = r12806 - r12809;
double r12811 = r12808 / r12810;
return r12811;
}
double f(double x) {
double r12812 = x;
double r12813 = -0.032009009980635265;
bool r12814 = r12812 <= r12813;
double r12815 = tan(r12812);
double r12816 = r12812 - r12815;
double r12817 = r12812 / r12816;
double r12818 = sin(r12812);
double r12819 = r12818 / r12816;
double r12820 = r12817 - r12819;
double r12821 = 0.024314219703607573;
bool r12822 = r12812 <= r12821;
double r12823 = 0.225;
double r12824 = 2.0;
double r12825 = pow(r12812, r12824);
double r12826 = r12823 * r12825;
double r12827 = 0.009642857142857142;
double r12828 = 4.0;
double r12829 = pow(r12812, r12828);
double r12830 = r12827 * r12829;
double r12831 = 0.5;
double r12832 = r12830 + r12831;
double r12833 = r12826 - r12832;
double r12834 = r12812 - r12818;
double r12835 = r12834 / r12816;
double r12836 = 3.0;
double r12837 = pow(r12835, r12836);
double r12838 = cbrt(r12837);
double r12839 = r12822 ? r12833 : r12838;
double r12840 = r12814 ? r12820 : r12839;
return r12840;
}



Bits error versus x
Results
if x < -0.032009009980635265Initial program 0.0
rmApplied div-sub0.0
if -0.032009009980635265 < x < 0.024314219703607573Initial program 63.1
Taylor expanded around 0 0.0
if 0.024314219703607573 < x Initial program 0.1
rmApplied add-cbrt-cube41.0
Applied add-cbrt-cube42.1
Applied cbrt-undiv42.1
Simplified0.1
Final simplification0.0
herbie shell --seed 2020036
(FPCore (x)
:name "sintan (problem 3.4.5)"
:precision binary64
(/ (- x (sin x)) (- x (tan x))))