
(FPCore (u s)
:precision binary32
(let* ((t_0 (/ 1.0 (+ 1.0 (exp (/ PI s))))))
(*
(- s)
(log
(-
(/ 1.0 (+ (* u (- (/ 1.0 (+ 1.0 (exp (/ (- PI) s)))) t_0)) t_0))
1.0)))))
float code(float u, float s) {
float t_0 = 1.0f / (1.0f + expf((((float) M_PI) / s)));
return -s * logf(((1.0f / ((u * ((1.0f / (1.0f + expf((-((float) M_PI) / s)))) - t_0)) + t_0)) - 1.0f));
}
function code(u, s) t_0 = Float32(Float32(1.0) / Float32(Float32(1.0) + exp(Float32(Float32(pi) / s)))) return Float32(Float32(-s) * log(Float32(Float32(Float32(1.0) / Float32(Float32(u * Float32(Float32(Float32(1.0) / Float32(Float32(1.0) + exp(Float32(Float32(-Float32(pi)) / s)))) - t_0)) + t_0)) - Float32(1.0)))) end
function tmp = code(u, s) t_0 = single(1.0) / (single(1.0) + exp((single(pi) / s))); tmp = -s * log(((single(1.0) / ((u * ((single(1.0) / (single(1.0) + exp((-single(pi) / s)))) - t_0)) + t_0)) - single(1.0))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{1 + e^{\frac{\pi}{s}}}\\
\left(-s\right) \cdot \log \left(\frac{1}{u \cdot \left(\frac{1}{1 + e^{\frac{-\pi}{s}}} - t\_0\right) + t\_0} - 1\right)
\end{array}
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 9 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (u s)
:precision binary32
(let* ((t_0 (/ 1.0 (+ 1.0 (exp (/ PI s))))))
(*
(- s)
(log
(-
(/ 1.0 (+ (* u (- (/ 1.0 (+ 1.0 (exp (/ (- PI) s)))) t_0)) t_0))
1.0)))))
float code(float u, float s) {
float t_0 = 1.0f / (1.0f + expf((((float) M_PI) / s)));
return -s * logf(((1.0f / ((u * ((1.0f / (1.0f + expf((-((float) M_PI) / s)))) - t_0)) + t_0)) - 1.0f));
}
function code(u, s) t_0 = Float32(Float32(1.0) / Float32(Float32(1.0) + exp(Float32(Float32(pi) / s)))) return Float32(Float32(-s) * log(Float32(Float32(Float32(1.0) / Float32(Float32(u * Float32(Float32(Float32(1.0) / Float32(Float32(1.0) + exp(Float32(Float32(-Float32(pi)) / s)))) - t_0)) + t_0)) - Float32(1.0)))) end
function tmp = code(u, s) t_0 = single(1.0) / (single(1.0) + exp((single(pi) / s))); tmp = -s * log(((single(1.0) / ((u * ((single(1.0) / (single(1.0) + exp((-single(pi) / s)))) - t_0)) + t_0)) - single(1.0))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{1 + e^{\frac{\pi}{s}}}\\
\left(-s\right) \cdot \log \left(\frac{1}{u \cdot \left(\frac{1}{1 + e^{\frac{-\pi}{s}}} - t\_0\right) + t\_0} - 1\right)
\end{array}
\end{array}
(FPCore (u s)
:precision binary32
(let* ((t_0
(+
(/ u (+ 1.0 (exp (/ (- PI) s))))
(/ (- 1.0 u) (+ 1.0 (pow (exp (/ 1.0 s)) PI))))))
(* (- s) (log1p (/ (- (pow t_0 -2.0) 4.0) (- (/ 1.0 t_0) -2.0))))))
float code(float u, float s) {
float t_0 = (u / (1.0f + expf((-((float) M_PI) / s)))) + ((1.0f - u) / (1.0f + powf(expf((1.0f / s)), ((float) M_PI))));
return -s * log1pf(((powf(t_0, -2.0f) - 4.0f) / ((1.0f / t_0) - -2.0f)));
}
function code(u, s) t_0 = Float32(Float32(u / Float32(Float32(1.0) + exp(Float32(Float32(-Float32(pi)) / s)))) + Float32(Float32(Float32(1.0) - u) / Float32(Float32(1.0) + (exp(Float32(Float32(1.0) / s)) ^ Float32(pi))))) return Float32(Float32(-s) * log1p(Float32(Float32((t_0 ^ Float32(-2.0)) - Float32(4.0)) / Float32(Float32(Float32(1.0) / t_0) - Float32(-2.0))))) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{u}{1 + e^{\frac{-\pi}{s}}} + \frac{1 - u}{1 + {\left(e^{\frac{1}{s}}\right)}^{\pi}}\\
\left(-s\right) \cdot \mathsf{log1p}\left(\frac{{t\_0}^{-2} - 4}{\frac{1}{t\_0} - -2}\right)
\end{array}
\end{array}
Initial program 98.9%
Simplified98.9%
clear-num98.9%
inv-pow98.9%
Applied egg-rr98.9%
unpow-198.9%
Simplified98.9%
log1p-expm1-u98.9%
expm1-undefine98.9%
Applied egg-rr98.9%
associate--l+98.9%
metadata-eval98.9%
Simplified98.9%
flip-+98.9%
Applied egg-rr99.0%
Final simplification99.0%
(FPCore (u s)
:precision binary32
(let* ((t_0
(+
(/ u (+ 1.0 (exp (/ (- PI) s))))
(/ (- 1.0 u) (+ 1.0 (exp (/ PI s)))))))
(* (- s) (log1p (/ (+ -4.0 (pow t_0 -2.0)) (+ 2.0 (/ 1.0 t_0)))))))
float code(float u, float s) {
float t_0 = (u / (1.0f + expf((-((float) M_PI) / s)))) + ((1.0f - u) / (1.0f + expf((((float) M_PI) / s))));
return -s * log1pf(((-4.0f + powf(t_0, -2.0f)) / (2.0f + (1.0f / t_0))));
}
function code(u, s) t_0 = Float32(Float32(u / Float32(Float32(1.0) + exp(Float32(Float32(-Float32(pi)) / s)))) + Float32(Float32(Float32(1.0) - u) / Float32(Float32(1.0) + exp(Float32(Float32(pi) / s))))) return Float32(Float32(-s) * log1p(Float32(Float32(Float32(-4.0) + (t_0 ^ Float32(-2.0))) / Float32(Float32(2.0) + Float32(Float32(1.0) / t_0))))) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{u}{1 + e^{\frac{-\pi}{s}}} + \frac{1 - u}{1 + e^{\frac{\pi}{s}}}\\
\left(-s\right) \cdot \mathsf{log1p}\left(\frac{-4 + {t\_0}^{-2}}{2 + \frac{1}{t\_0}}\right)
\end{array}
\end{array}
Initial program 98.9%
Simplified98.9%
clear-num98.9%
inv-pow98.9%
Applied egg-rr98.9%
unpow-198.9%
Simplified98.9%
log1p-expm1-u98.9%
expm1-undefine98.9%
Applied egg-rr98.9%
associate--l+98.9%
metadata-eval98.9%
Simplified98.9%
flip-+98.9%
Applied egg-rr99.0%
*-un-lft-identity99.0%
Applied egg-rr99.0%
*-lft-identity99.0%
+-commutative99.0%
+-commutative99.0%
Simplified99.0%
Final simplification99.0%
(FPCore (u s)
:precision binary32
(*
s
(-
(log
(+
(/
1.0
(+
(/ u (+ 1.0 (exp (/ (- PI) s))))
(/ (- 1.0 u) (+ 1.0 (exp (/ PI s))))))
-1.0)))))
float code(float u, float s) {
return s * -logf(((1.0f / ((u / (1.0f + expf((-((float) M_PI) / s)))) + ((1.0f - u) / (1.0f + expf((((float) M_PI) / s)))))) + -1.0f));
}
function code(u, s) return Float32(s * Float32(-log(Float32(Float32(Float32(1.0) / Float32(Float32(u / Float32(Float32(1.0) + exp(Float32(Float32(-Float32(pi)) / s)))) + Float32(Float32(Float32(1.0) - u) / Float32(Float32(1.0) + exp(Float32(Float32(pi) / s)))))) + Float32(-1.0))))) end
function tmp = code(u, s) tmp = s * -log(((single(1.0) / ((u / (single(1.0) + exp((-single(pi) / s)))) + ((single(1.0) - u) / (single(1.0) + exp((single(pi) / s)))))) + single(-1.0))); end
\begin{array}{l}
\\
s \cdot \left(-\log \left(\frac{1}{\frac{u}{1 + e^{\frac{-\pi}{s}}} + \frac{1 - u}{1 + e^{\frac{\pi}{s}}}} + -1\right)\right)
\end{array}
Initial program 98.9%
Simplified98.9%
Final simplification98.9%
(FPCore (u s) :precision binary32 (* s (- (log (+ 1.0 (* 4.0 (/ (- (* -0.25 (* u PI)) (* PI -0.25)) s)))))))
float code(float u, float s) {
return s * -logf((1.0f + (4.0f * (((-0.25f * (u * ((float) M_PI))) - (((float) M_PI) * -0.25f)) / s))));
}
function code(u, s) return Float32(s * Float32(-log(Float32(Float32(1.0) + Float32(Float32(4.0) * Float32(Float32(Float32(Float32(-0.25) * Float32(u * Float32(pi))) - Float32(Float32(pi) * Float32(-0.25))) / s)))))) end
function tmp = code(u, s) tmp = s * -log((single(1.0) + (single(4.0) * (((single(-0.25) * (u * single(pi))) - (single(pi) * single(-0.25))) / s)))); end
\begin{array}{l}
\\
s \cdot \left(-\log \left(1 + 4 \cdot \frac{-0.25 \cdot \left(u \cdot \pi\right) - \pi \cdot -0.25}{s}\right)\right)
\end{array}
Initial program 98.9%
Simplified98.9%
Taylor expanded in s around -inf 25.9%
Taylor expanded in u around 0 26.0%
*-commutative26.0%
Simplified26.0%
Final simplification26.0%
(FPCore (u s) :precision binary32 (* (- s) (log (+ 1.0 (* 4.0 (* (/ PI s) 0.25))))))
float code(float u, float s) {
return -s * logf((1.0f + (4.0f * ((((float) M_PI) / s) * 0.25f))));
}
function code(u, s) return Float32(Float32(-s) * log(Float32(Float32(1.0) + Float32(Float32(4.0) * Float32(Float32(Float32(pi) / s) * Float32(0.25)))))) end
function tmp = code(u, s) tmp = -s * log((single(1.0) + (single(4.0) * ((single(pi) / s) * single(0.25))))); end
\begin{array}{l}
\\
\left(-s\right) \cdot \log \left(1 + 4 \cdot \left(\frac{\pi}{s} \cdot 0.25\right)\right)
\end{array}
Initial program 98.9%
Simplified98.9%
Taylor expanded in s around -inf 25.9%
Taylor expanded in u around 0 26.0%
*-commutative26.0%
Simplified26.0%
(FPCore (u s) :precision binary32 (* -4.0 (* PI (+ (fma u -0.25 0.25) (* u -0.25)))))
float code(float u, float s) {
return -4.0f * (((float) M_PI) * (fmaf(u, -0.25f, 0.25f) + (u * -0.25f)));
}
function code(u, s) return Float32(Float32(-4.0) * Float32(Float32(pi) * Float32(fma(u, Float32(-0.25), Float32(0.25)) + Float32(u * Float32(-0.25))))) end
\begin{array}{l}
\\
-4 \cdot \left(\pi \cdot \left(\mathsf{fma}\left(u, -0.25, 0.25\right) + u \cdot -0.25\right)\right)
\end{array}
Initial program 98.9%
Simplified98.9%
Taylor expanded in s around -inf 11.7%
associate--r+11.7%
cancel-sign-sub-inv11.7%
cancel-sign-sub-inv11.7%
metadata-eval11.7%
associate-*r*11.7%
distribute-rgt-out11.7%
metadata-eval11.7%
*-commutative11.7%
*-commutative11.7%
associate-*l*11.7%
Simplified11.7%
*-un-lft-identity11.7%
distribute-lft-out11.7%
*-commutative11.7%
fma-define11.7%
Applied egg-rr11.7%
*-lft-identity11.7%
Simplified11.7%
(FPCore (u s) :precision binary32 (* PI (+ -1.0 (* u 2.0))))
float code(float u, float s) {
return ((float) M_PI) * (-1.0f + (u * 2.0f));
}
function code(u, s) return Float32(Float32(pi) * Float32(Float32(-1.0) + Float32(u * Float32(2.0)))) end
function tmp = code(u, s) tmp = single(pi) * (single(-1.0) + (u * single(2.0))); end
\begin{array}{l}
\\
\pi \cdot \left(-1 + u \cdot 2\right)
\end{array}
Initial program 98.9%
Simplified98.9%
Taylor expanded in s around -inf 11.7%
associate--r+11.7%
cancel-sign-sub-inv11.7%
cancel-sign-sub-inv11.7%
metadata-eval11.7%
associate-*r*11.7%
distribute-rgt-out11.7%
metadata-eval11.7%
*-commutative11.7%
*-commutative11.7%
associate-*l*11.7%
Simplified11.7%
Taylor expanded in u around 0 11.7%
neg-mul-111.7%
+-commutative11.7%
associate-*r*11.7%
neg-mul-111.7%
distribute-rgt-out11.7%
Simplified11.7%
Final simplification11.7%
(FPCore (u s) :precision binary32 (- PI))
float code(float u, float s) {
return -((float) M_PI);
}
function code(u, s) return Float32(-Float32(pi)) end
function tmp = code(u, s) tmp = -single(pi); end
\begin{array}{l}
\\
-\pi
\end{array}
Initial program 98.9%
Simplified98.9%
Taylor expanded in u around 0 11.5%
neg-mul-111.5%
Simplified11.5%
(FPCore (u s) :precision binary32 0.0)
float code(float u, float s) {
return 0.0f;
}
real(4) function code(u, s)
real(4), intent (in) :: u
real(4), intent (in) :: s
code = 0.0e0
end function
function code(u, s) return Float32(0.0) end
function tmp = code(u, s) tmp = single(0.0); end
\begin{array}{l}
\\
0
\end{array}
Initial program 98.9%
Simplified98.9%
clear-num98.9%
inv-pow98.9%
Applied egg-rr98.9%
unpow-198.9%
Simplified98.9%
add-exp-log98.8%
log-rec98.7%
associate-/r/98.7%
exp-prod98.7%
Applied egg-rr98.7%
Taylor expanded in s around inf 10.0%
mul-1-neg10.0%
distribute-rgt-neg-in10.0%
exp-neg10.0%
rem-exp-log10.0%
metadata-eval10.0%
metadata-eval10.0%
metadata-eval10.0%
metadata-eval10.0%
Simplified10.0%
Taylor expanded in s around 0 10.0%
herbie shell --seed 2024143
(FPCore (u s)
:name "Sample trimmed logistic on [-pi, pi]"
:precision binary32
:pre (and (and (<= 2.328306437e-10 u) (<= u 1.0)) (and (<= 0.0 s) (<= s 1.0651631)))
(* (- s) (log (- (/ 1.0 (+ (* u (- (/ 1.0 (+ 1.0 (exp (/ (- PI) s)))) (/ 1.0 (+ 1.0 (exp (/ PI s)))))) (/ 1.0 (+ 1.0 (exp (/ PI s)))))) 1.0))))