\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 r24244 = 1.0;
double r24245 = x;
double r24246 = cos(r24245);
double r24247 = r24244 - r24246;
double r24248 = r24245 * r24245;
double r24249 = r24247 / r24248;
return r24249;
}
double f(double x) {
double r24250 = x;
double r24251 = -0.03408999554764363;
bool r24252 = r24250 <= r24251;
double r24253 = 1.0;
double r24254 = 3.0;
double r24255 = pow(r24253, r24254);
double r24256 = cos(r24250);
double r24257 = pow(r24256, r24254);
double r24258 = r24255 - r24257;
double r24259 = exp(r24258);
double r24260 = log(r24259);
double r24261 = r24256 + r24253;
double r24262 = r24256 * r24261;
double r24263 = r24253 * r24253;
double r24264 = r24262 + r24263;
double r24265 = r24260 / r24264;
double r24266 = r24265 / r24250;
double r24267 = r24266 / r24250;
double r24268 = 0.031210463015068444;
bool r24269 = r24250 <= r24268;
double r24270 = 0.001388888888888889;
double r24271 = 4.0;
double r24272 = pow(r24250, r24271);
double r24273 = r24270 * r24272;
double r24274 = 0.5;
double r24275 = r24273 + r24274;
double r24276 = 0.041666666666666664;
double r24277 = 2.0;
double r24278 = pow(r24250, r24277);
double r24279 = r24276 * r24278;
double r24280 = r24275 - r24279;
double r24281 = r24253 - r24256;
double r24282 = r24264 * r24281;
double r24283 = r24282 / r24264;
double r24284 = r24283 / r24250;
double r24285 = r24284 / r24250;
double r24286 = r24269 ? r24280 : r24285;
double r24287 = r24252 ? r24267 : r24286;
return r24287;
}



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)))