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 r180456 = x;
double r180457 = 1.0;
double r180458 = y;
double r180459 = r180457 - r180458;
double r180460 = z;
double r180461 = exp(r180460);
double r180462 = r180458 * r180461;
double r180463 = r180459 + r180462;
double r180464 = log(r180463);
double r180465 = t;
double r180466 = r180464 / r180465;
double r180467 = r180456 - r180466;
return r180467;
}
double f(double x, double y, double z, double t) {
double r180468 = z;
double r180469 = -0.3115017031960372;
bool r180470 = r180468 <= r180469;
double r180471 = x;
double r180472 = expm1(r180468);
double r180473 = y;
double r180474 = 1.0;
double r180475 = fma(r180472, r180473, r180474);
double r180476 = log(r180475);
double r180477 = sqrt(r180476);
double r180478 = t;
double r180479 = r180477 / r180478;
double r180480 = r180477 * r180479;
double r180481 = r180471 - r180480;
double r180482 = 1.0;
double r180483 = 0.5;
double r180484 = 2.0;
double r180485 = pow(r180468, r180484);
double r180486 = r180474 * r180468;
double r180487 = fma(r180483, r180485, r180486);
double r180488 = log(r180474);
double r180489 = fma(r180473, r180487, r180488);
double r180490 = r180478 / r180489;
double r180491 = r180482 / r180490;
double r180492 = r180471 - r180491;
double r180493 = r180470 ? r180481 : r180492;
return r180493;
}




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)))