\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 := \sin \left(0.005555555555555556 \cdot \left(angle \cdot \pi\right)\right)\\
\left(2 \cdot \left({b}^{2} \cdot t_0\right) - 2 \cdot \left(t_0 \cdot {a}^{2}\right)\right) \cdot \cos \left(\pi \cdot \frac{angle}{180}\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 (sin (* 0.005555555555555556 (* angle PI)))))
(*
(- (* 2.0 (* (pow b 2.0) t_0)) (* 2.0 (* t_0 (pow a 2.0))))
(cos (* PI (/ angle 180.0))))))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 = sin(0.005555555555555556 * (angle * ((double) M_PI)));
return ((2.0 * (pow(b, 2.0) * t_0)) - (2.0 * (t_0 * pow(a, 2.0)))) * cos(((double) M_PI) * (angle / 180.0));
}



Bits error versus a



Bits error versus b



Bits error versus angle
Results
Initial program 30.8
Taylor expanded in b around 0 30.8
Final simplification30.8
herbie shell --seed 2022024
(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)))))