\left(\left(\left(a + \frac{1}{2} \cdot a\right) + \frac{1}{6} \cdot {a}^{2}\right) + \frac{1}{24} \cdot {a}^{3}\right) + \frac{1}{120} \cdot {a}^{4}\left(\left(\left(a + \frac{1}{2} \cdot a\right) + \frac{1}{6} \cdot {a}^{2}\right) + \frac{1}{24} \cdot {a}^{3}\right) + \frac{1}{120} \cdot {a}^{4}double code(double a) {
return ((double) (((double) (((double) (((double) (a + ((double) (((double) (1.0 / 2.0)) * a)))) + ((double) (((double) (1.0 / 6.0)) * ((double) pow(a, 2.0)))))) + ((double) (((double) (1.0 / 24.0)) * ((double) pow(a, 3.0)))))) + ((double) (((double) (1.0 / 120.0)) * ((double) pow(a, 4.0))))));
}
double code(double a) {
return ((double) (((double) (((double) (((double) (a + ((double) (((double) (1.0 / 2.0)) * a)))) + ((double) (((double) (1.0 / 6.0)) * ((double) pow(a, 2.0)))))) + ((double) (((double) (1.0 / 24.0)) * ((double) pow(a, 3.0)))))) + ((double) (((double) (1.0 / 120.0)) * ((double) pow(a, 4.0))))));
}



Bits error versus a
Results
Initial program 0.3
Final simplification0.3
herbie shell --seed 2020153
(FPCore (a)
:name "(+ (+ (+ (+ a (* (/ 1 2) a)) (* (/ 1 6) (pow a 2))) (* (/ 1 24) (pow a 3))) (* (/ 1 120) (pow a 4)))"
:precision binary64
(+ (+ (+ (+ a (* (/ 1.0 2.0) a)) (* (/ 1.0 6.0) (pow a 2.0))) (* (/ 1.0 24.0) (pow a 3.0))) (* (/ 1.0 120.0) (pow a 4.0))))