x - \frac{\log \left(\left(1 - y\right) + y \cdot e^{z}\right)}{t}\begin{array}{l}
\mathbf{if}\;z \le -0.3115017031960372051457852649036794900894:\\
\;\;\;\;x - \sqrt{\log \left(\mathsf{fma}\left(\mathsf{expm1}\left(z\right), y, 1\right)\right)} \cdot \frac{\sqrt{\log \left(\mathsf{fma}\left(\mathsf{expm1}\left(z\right), y, 1\right)\right)}}{t}\\
\mathbf{else}:\\
\;\;\;\;x - \frac{1}{\frac{t}{\mathsf{fma}\left(y, \mathsf{fma}\left(0.5, {z}^{2}, 1 \cdot z\right), \log 1\right)}}\\
\end{array}double f(double x, double y, double z, double t) {
double r231967 = x;
double r231968 = 1.0;
double r231969 = y;
double r231970 = r231968 - r231969;
double r231971 = z;
double r231972 = exp(r231971);
double r231973 = r231969 * r231972;
double r231974 = r231970 + r231973;
double r231975 = log(r231974);
double r231976 = t;
double r231977 = r231975 / r231976;
double r231978 = r231967 - r231977;
return r231978;
}
double f(double x, double y, double z, double t) {
double r231979 = z;
double r231980 = -0.3115017031960372;
bool r231981 = r231979 <= r231980;
double r231982 = x;
double r231983 = expm1(r231979);
double r231984 = y;
double r231985 = 1.0;
double r231986 = fma(r231983, r231984, r231985);
double r231987 = log(r231986);
double r231988 = sqrt(r231987);
double r231989 = t;
double r231990 = r231988 / r231989;
double r231991 = r231988 * r231990;
double r231992 = r231982 - r231991;
double r231993 = 1.0;
double r231994 = 0.5;
double r231995 = 2.0;
double r231996 = pow(r231979, r231995);
double r231997 = r231985 * r231979;
double r231998 = fma(r231994, r231996, r231997);
double r231999 = log(r231985);
double r232000 = fma(r231984, r231998, r231999);
double r232001 = r231989 / r232000;
double r232002 = r231993 / r232001;
double r232003 = r231982 - r232002;
double r232004 = r231981 ? r231992 : r232003;
return r232004;
}




Bits error versus x




Bits error versus y




Bits error versus z




Bits error versus t
| Original | 25.4 |
|---|---|
| Target | 16.5 |
| Herbie | 8.8 |
if z < -0.3115017031960372Initial program 10.9
Simplified10.9
rmApplied *-un-lft-identity10.9
Applied add-sqr-sqrt11.8
Applied times-frac11.8
Simplified11.8
if -0.3115017031960372 < z Initial program 31.3
Simplified11.9
rmApplied clear-num11.9
Taylor expanded around 0 7.6
Simplified7.6
Final simplification8.8
herbie shell --seed 2019303 +o rules:numerics
(FPCore (x y z t)
:name "System.Random.MWC.Distributions:truncatedExp from mwc-random-0.13.3.2"
:precision binary64
:herbie-target
(if (< z -2.88746230882079466e119) (- (- x (/ (/ (- 0.5) (* y t)) (* z z))) (* (/ (- 0.5) (* y t)) (/ (/ 2 z) (* z z)))) (- x (/ (log (+ 1 (* z y))) t)))
(- x (/ (log (+ (- 1 y) (* y (exp z)))) t)))