\left(\left(2 \cdot \left({b}^{2} - {a}^{2}\right)\right) \cdot \sin \left(\pi \cdot \frac{angle}{180}\right)\right) \cdot \cos \left(\pi \cdot \frac{angle}{180}\right)
\begin{array}{l}
t_0 := \pi \cdot \frac{angle}{180}\\
t_1 := \cos t_0\\
t_2 := \sqrt[3]{t_1}\\
\left(\left(2 \cdot \left({b}^{2} - {a}^{2}\right)\right) \cdot \mathsf{log1p}\left(\mathsf{expm1}\left(\sin t_0\right)\right)\right) \cdot \left(\left(\sqrt[3]{\sqrt[3]{t_1 \cdot \left(t_1 \cdot t_1\right)}} \cdot t_2\right) \cdot \sqrt[3]{t_2 \cdot \left(t_2 \cdot t_2\right)}\right)
\end{array}
(FPCore (a b angle) :precision binary64 (* (* (* 2.0 (- (pow b 2.0) (pow a 2.0))) (sin (* PI (/ angle 180.0)))) (cos (* PI (/ angle 180.0)))))
(FPCore (a b angle)
:precision binary64
(let* ((t_0 (* PI (/ angle 180.0))) (t_1 (cos t_0)) (t_2 (cbrt t_1)))
(*
(* (* 2.0 (- (pow b 2.0) (pow a 2.0))) (log1p (expm1 (sin t_0))))
(* (* (cbrt (cbrt (* t_1 (* t_1 t_1)))) t_2) (cbrt (* t_2 (* t_2 t_2)))))))double code(double a, double b, double angle) {
return ((2.0 * (pow(b, 2.0) - pow(a, 2.0))) * sin(((double) M_PI) * (angle / 180.0))) * cos(((double) M_PI) * (angle / 180.0));
}
double code(double a, double b, double angle) {
double t_0 = ((double) M_PI) * (angle / 180.0);
double t_1 = cos(t_0);
double t_2 = cbrt(t_1);
return ((2.0 * (pow(b, 2.0) - pow(a, 2.0))) * log1p(expm1(sin(t_0)))) * ((cbrt(cbrt(t_1 * (t_1 * t_1))) * t_2) * cbrt(t_2 * (t_2 * t_2)));
}



Bits error versus a



Bits error versus b



Bits error versus angle
Results
Initial program 31.8
Applied add-cube-cbrt_binary6431.8
Applied log1p-expm1-u_binary6431.8
Applied add-cube-cbrt_binary6431.8
Applied add-cbrt-cube_binary6431.8
Final simplification31.8
herbie shell --seed 2021224
(FPCore (a b angle)
:name "ab-angle->ABCF B"
:precision binary64
(* (* (* 2.0 (- (pow b 2.0) (pow a 2.0))) (sin (* PI (/ angle 180.0)))) (cos (* PI (/ angle 180.0)))))