\frac{x - \sin x}{x - \tan x}\begin{array}{l}
\mathbf{if}\;x \le -0.029116187280256105:\\
\;\;\;\;\left(\sqrt[3]{\frac{x - \sin x}{x - \tan x}} \cdot \sqrt[3]{\frac{x - \sin x}{x - \tan x}}\right) \cdot \sqrt[3]{\frac{x - \sin x}{x - \tan x}}\\
\mathbf{elif}\;x \le 0.03078436997544294:\\
\;\;\;\;\frac{-1}{2} + \left(\frac{9}{40} - \left(x \cdot x\right) \cdot \frac{27}{2800}\right) \cdot \left(x \cdot x\right)\\
\mathbf{else}:\\
\;\;\;\;\frac{x}{x - \tan x} - \frac{\sin x}{x - \tan x}\\
\end{array}double f(double x) {
double r1533114 = x;
double r1533115 = sin(r1533114);
double r1533116 = r1533114 - r1533115;
double r1533117 = tan(r1533114);
double r1533118 = r1533114 - r1533117;
double r1533119 = r1533116 / r1533118;
return r1533119;
}
double f(double x) {
double r1533120 = x;
double r1533121 = -0.029116187280256105;
bool r1533122 = r1533120 <= r1533121;
double r1533123 = sin(r1533120);
double r1533124 = r1533120 - r1533123;
double r1533125 = tan(r1533120);
double r1533126 = r1533120 - r1533125;
double r1533127 = r1533124 / r1533126;
double r1533128 = cbrt(r1533127);
double r1533129 = r1533128 * r1533128;
double r1533130 = r1533129 * r1533128;
double r1533131 = 0.03078436997544294;
bool r1533132 = r1533120 <= r1533131;
double r1533133 = -0.5;
double r1533134 = 0.225;
double r1533135 = r1533120 * r1533120;
double r1533136 = 0.009642857142857142;
double r1533137 = r1533135 * r1533136;
double r1533138 = r1533134 - r1533137;
double r1533139 = r1533138 * r1533135;
double r1533140 = r1533133 + r1533139;
double r1533141 = r1533120 / r1533126;
double r1533142 = r1533123 / r1533126;
double r1533143 = r1533141 - r1533142;
double r1533144 = r1533132 ? r1533140 : r1533143;
double r1533145 = r1533122 ? r1533130 : r1533144;
return r1533145;
}



Bits error versus x
Results
if x < -0.029116187280256105Initial program 0.0
rmApplied add-cube-cbrt0.1
if -0.029116187280256105 < x < 0.03078436997544294Initial program 62.7
Taylor expanded around 0 0.0
Simplified0.0
if 0.03078436997544294 < x Initial program 0.0
rmApplied div-sub0.0
Final simplification0.0
herbie shell --seed 2019128
(FPCore (x)
:name "sintan (problem 3.4.5)"
(/ (- x (sin x)) (- x (tan x))))