\frac{1 - \cos x}{x \cdot x}\begin{array}{l}
\mathbf{if}\;x \le -0.03408999554764362976966296514547138940543:\\
\;\;\;\;\frac{\frac{\frac{\log \left(e^{{1}^{3} - {\left(\cos x\right)}^{3}}\right)}{\cos x \cdot \left(\cos x + 1\right) + 1 \cdot 1}}{x}}{x}\\
\mathbf{elif}\;x \le 0.03121046301506844380946326111825328553095:\\
\;\;\;\;\left(\frac{1}{720} \cdot {x}^{4} + \frac{1}{2}\right) - \frac{1}{24} \cdot {x}^{2}\\
\mathbf{else}:\\
\;\;\;\;\frac{\frac{\frac{\left(\cos x \cdot \left(\cos x + 1\right) + 1 \cdot 1\right) \cdot \left(1 - \cos x\right)}{\cos x \cdot \left(\cos x + 1\right) + 1 \cdot 1}}{x}}{x}\\
\end{array}double f(double x) {
double r23857 = 1.0;
double r23858 = x;
double r23859 = cos(r23858);
double r23860 = r23857 - r23859;
double r23861 = r23858 * r23858;
double r23862 = r23860 / r23861;
return r23862;
}
double f(double x) {
double r23863 = x;
double r23864 = -0.03408999554764363;
bool r23865 = r23863 <= r23864;
double r23866 = 1.0;
double r23867 = 3.0;
double r23868 = pow(r23866, r23867);
double r23869 = cos(r23863);
double r23870 = pow(r23869, r23867);
double r23871 = r23868 - r23870;
double r23872 = exp(r23871);
double r23873 = log(r23872);
double r23874 = r23869 + r23866;
double r23875 = r23869 * r23874;
double r23876 = r23866 * r23866;
double r23877 = r23875 + r23876;
double r23878 = r23873 / r23877;
double r23879 = r23878 / r23863;
double r23880 = r23879 / r23863;
double r23881 = 0.031210463015068444;
bool r23882 = r23863 <= r23881;
double r23883 = 0.001388888888888889;
double r23884 = 4.0;
double r23885 = pow(r23863, r23884);
double r23886 = r23883 * r23885;
double r23887 = 0.5;
double r23888 = r23886 + r23887;
double r23889 = 0.041666666666666664;
double r23890 = 2.0;
double r23891 = pow(r23863, r23890);
double r23892 = r23889 * r23891;
double r23893 = r23888 - r23892;
double r23894 = r23866 - r23869;
double r23895 = r23877 * r23894;
double r23896 = r23895 / r23877;
double r23897 = r23896 / r23863;
double r23898 = r23897 / r23863;
double r23899 = r23882 ? r23893 : r23898;
double r23900 = r23865 ? r23880 : r23899;
return r23900;
}



Bits error versus x
Results
if x < -0.03408999554764363Initial program 1.1
rmApplied associate-/r*0.4
rmApplied flip3--0.5
Simplified0.5
rmApplied add-log-exp0.5
Applied add-log-exp0.5
Applied diff-log0.6
Simplified0.5
if -0.03408999554764363 < x < 0.031210463015068444Initial program 62.4
Taylor expanded around 0 0.0
if 0.031210463015068444 < x Initial program 1.0
rmApplied associate-/r*0.4
rmApplied flip3--0.5
Simplified0.5
rmApplied difference-cubes0.5
Simplified0.4
Final simplification0.2
herbie shell --seed 2020001
(FPCore (x)
:name "cos2 (problem 3.4.1)"
:precision binary64
(/ (- 1 (cos x)) (* x x)))