
(FPCore (cosTheta alpha)
:precision binary32
(let* ((t_0 (- (* alpha alpha) 1.0)))
(/
t_0
(* (* PI (log (* alpha alpha))) (+ 1.0 (* (* t_0 cosTheta) cosTheta))))))
float code(float cosTheta, float alpha) {
float t_0 = (alpha * alpha) - 1.0f;
return t_0 / ((((float) M_PI) * logf((alpha * alpha))) * (1.0f + ((t_0 * cosTheta) * cosTheta)));
}
function code(cosTheta, alpha) t_0 = Float32(Float32(alpha * alpha) - Float32(1.0)) return Float32(t_0 / Float32(Float32(Float32(pi) * log(Float32(alpha * alpha))) * Float32(Float32(1.0) + Float32(Float32(t_0 * cosTheta) * cosTheta)))) end
function tmp = code(cosTheta, alpha) t_0 = (alpha * alpha) - single(1.0); tmp = t_0 / ((single(pi) * log((alpha * alpha))) * (single(1.0) + ((t_0 * cosTheta) * cosTheta))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \alpha \cdot \alpha - 1\\
\frac{t\_0}{\left(\pi \cdot \log \left(\alpha \cdot \alpha\right)\right) \cdot \left(1 + \left(t\_0 \cdot cosTheta\right) \cdot cosTheta\right)}
\end{array}
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 8 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (cosTheta alpha)
:precision binary32
(let* ((t_0 (- (* alpha alpha) 1.0)))
(/
t_0
(* (* PI (log (* alpha alpha))) (+ 1.0 (* (* t_0 cosTheta) cosTheta))))))
float code(float cosTheta, float alpha) {
float t_0 = (alpha * alpha) - 1.0f;
return t_0 / ((((float) M_PI) * logf((alpha * alpha))) * (1.0f + ((t_0 * cosTheta) * cosTheta)));
}
function code(cosTheta, alpha) t_0 = Float32(Float32(alpha * alpha) - Float32(1.0)) return Float32(t_0 / Float32(Float32(Float32(pi) * log(Float32(alpha * alpha))) * Float32(Float32(1.0) + Float32(Float32(t_0 * cosTheta) * cosTheta)))) end
function tmp = code(cosTheta, alpha) t_0 = (alpha * alpha) - single(1.0); tmp = t_0 / ((single(pi) * log((alpha * alpha))) * (single(1.0) + ((t_0 * cosTheta) * cosTheta))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \alpha \cdot \alpha - 1\\
\frac{t\_0}{\left(\pi \cdot \log \left(\alpha \cdot \alpha\right)\right) \cdot \left(1 + \left(t\_0 \cdot cosTheta\right) \cdot cosTheta\right)}
\end{array}
\end{array}
(FPCore (cosTheta alpha)
:precision binary32
(/
(fma alpha alpha -1.0)
(*
PI
(*
(* 2.0 (log alpha))
(+ 1.0 (* cosTheta (* cosTheta (* (+ alpha -1.0) (+ alpha 1.0)))))))))
float code(float cosTheta, float alpha) {
return fmaf(alpha, alpha, -1.0f) / (((float) M_PI) * ((2.0f * logf(alpha)) * (1.0f + (cosTheta * (cosTheta * ((alpha + -1.0f) * (alpha + 1.0f)))))));
}
function code(cosTheta, alpha) return Float32(fma(alpha, alpha, Float32(-1.0)) / Float32(Float32(pi) * Float32(Float32(Float32(2.0) * log(alpha)) * Float32(Float32(1.0) + Float32(cosTheta * Float32(cosTheta * Float32(Float32(alpha + Float32(-1.0)) * Float32(alpha + Float32(1.0))))))))) end
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\alpha, \alpha, -1\right)}{\pi \cdot \left(\left(2 \cdot \log \alpha\right) \cdot \left(1 + cosTheta \cdot \left(cosTheta \cdot \left(\left(\alpha + -1\right) \cdot \left(\alpha + 1\right)\right)\right)\right)\right)}
\end{array}
Initial program 98.6%
associate-/r*98.6%
cancel-sign-sub98.6%
distribute-rgt-neg-out98.6%
unsub-neg98.6%
distribute-rgt-neg-out98.6%
associate-/r*98.6%
fma-neg98.3%
metadata-eval98.3%
associate-*l*98.3%
*-commutative98.3%
distribute-rgt-neg-out98.3%
Simplified98.3%
Taylor expanded in alpha around 0 98.7%
fma-undefine98.7%
difference-of-sqr--198.7%
sub-neg98.7%
metadata-eval98.7%
Applied egg-rr98.7%
Final simplification98.7%
(FPCore (cosTheta alpha)
:precision binary32
(let* ((t_0 (+ -1.0 (* alpha alpha))))
(/
t_0
(* (* PI (log (* alpha alpha))) (+ 1.0 (* cosTheta (* cosTheta t_0)))))))
float code(float cosTheta, float alpha) {
float t_0 = -1.0f + (alpha * alpha);
return t_0 / ((((float) M_PI) * logf((alpha * alpha))) * (1.0f + (cosTheta * (cosTheta * t_0))));
}
function code(cosTheta, alpha) t_0 = Float32(Float32(-1.0) + Float32(alpha * alpha)) return Float32(t_0 / Float32(Float32(Float32(pi) * log(Float32(alpha * alpha))) * Float32(Float32(1.0) + Float32(cosTheta * Float32(cosTheta * t_0))))) end
function tmp = code(cosTheta, alpha) t_0 = single(-1.0) + (alpha * alpha); tmp = t_0 / ((single(pi) * log((alpha * alpha))) * (single(1.0) + (cosTheta * (cosTheta * t_0)))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := -1 + \alpha \cdot \alpha\\
\frac{t\_0}{\left(\pi \cdot \log \left(\alpha \cdot \alpha\right)\right) \cdot \left(1 + cosTheta \cdot \left(cosTheta \cdot t\_0\right)\right)}
\end{array}
\end{array}
Initial program 98.6%
Final simplification98.6%
(FPCore (cosTheta alpha) :precision binary32 (/ (+ -1.0 (* alpha alpha)) (* (* PI (log (* alpha alpha))) (- 1.0 (* cosTheta cosTheta)))))
float code(float cosTheta, float alpha) {
return (-1.0f + (alpha * alpha)) / ((((float) M_PI) * logf((alpha * alpha))) * (1.0f - (cosTheta * cosTheta)));
}
function code(cosTheta, alpha) return Float32(Float32(Float32(-1.0) + Float32(alpha * alpha)) / Float32(Float32(Float32(pi) * log(Float32(alpha * alpha))) * Float32(Float32(1.0) - Float32(cosTheta * cosTheta)))) end
function tmp = code(cosTheta, alpha) tmp = (single(-1.0) + (alpha * alpha)) / ((single(pi) * log((alpha * alpha))) * (single(1.0) - (cosTheta * cosTheta))); end
\begin{array}{l}
\\
\frac{-1 + \alpha \cdot \alpha}{\left(\pi \cdot \log \left(\alpha \cdot \alpha\right)\right) \cdot \left(1 - cosTheta \cdot cosTheta\right)}
\end{array}
Initial program 98.6%
Taylor expanded in alpha around 0 97.7%
Simplified97.7%
Final simplification97.7%
(FPCore (cosTheta alpha) :precision binary32 (* 0.5 (/ (* (+ alpha -1.0) (+ alpha 1.0)) (* PI (log alpha)))))
float code(float cosTheta, float alpha) {
return 0.5f * (((alpha + -1.0f) * (alpha + 1.0f)) / (((float) M_PI) * logf(alpha)));
}
function code(cosTheta, alpha) return Float32(Float32(0.5) * Float32(Float32(Float32(alpha + Float32(-1.0)) * Float32(alpha + Float32(1.0))) / Float32(Float32(pi) * log(alpha)))) end
function tmp = code(cosTheta, alpha) tmp = single(0.5) * (((alpha + single(-1.0)) * (alpha + single(1.0))) / (single(pi) * log(alpha))); end
\begin{array}{l}
\\
0.5 \cdot \frac{\left(\alpha + -1\right) \cdot \left(\alpha + 1\right)}{\pi \cdot \log \alpha}
\end{array}
Initial program 98.6%
associate-/r*98.6%
fma-neg98.4%
metadata-eval98.4%
+-commutative98.4%
associate-*l*98.4%
fma-define98.4%
fma-neg98.4%
metadata-eval98.4%
Simplified98.4%
div-inv98.2%
fma-undefine98.4%
difference-of-sqr--198.1%
associate-*l*97.9%
sub-neg97.9%
metadata-eval97.9%
associate-/r*97.8%
pow297.8%
log-pow98.1%
Applied egg-rr98.1%
Taylor expanded in cosTheta around 0 95.0%
Final simplification95.0%
(FPCore (cosTheta alpha) :precision binary32 (* 0.5 (* (/ (+ alpha 1.0) PI) (/ (+ alpha -1.0) (log alpha)))))
float code(float cosTheta, float alpha) {
return 0.5f * (((alpha + 1.0f) / ((float) M_PI)) * ((alpha + -1.0f) / logf(alpha)));
}
function code(cosTheta, alpha) return Float32(Float32(0.5) * Float32(Float32(Float32(alpha + Float32(1.0)) / Float32(pi)) * Float32(Float32(alpha + Float32(-1.0)) / log(alpha)))) end
function tmp = code(cosTheta, alpha) tmp = single(0.5) * (((alpha + single(1.0)) / single(pi)) * ((alpha + single(-1.0)) / log(alpha))); end
\begin{array}{l}
\\
0.5 \cdot \left(\frac{\alpha + 1}{\pi} \cdot \frac{\alpha + -1}{\log \alpha}\right)
\end{array}
Initial program 98.6%
associate-/r*98.6%
fma-neg98.4%
metadata-eval98.4%
+-commutative98.4%
associate-*l*98.4%
fma-define98.4%
fma-neg98.4%
metadata-eval98.4%
Simplified98.4%
div-inv98.2%
fma-undefine98.4%
difference-of-sqr--198.1%
associate-*l*97.9%
sub-neg97.9%
metadata-eval97.9%
associate-/r*97.8%
pow297.8%
log-pow98.1%
Applied egg-rr98.1%
Taylor expanded in cosTheta around 0 95.0%
times-frac94.9%
sub-neg94.9%
metadata-eval94.9%
Applied egg-rr94.9%
Final simplification94.9%
(FPCore (cosTheta alpha) :precision binary32 (* 0.5 (* (+ alpha 1.0) (/ (+ alpha -1.0) (* PI (log alpha))))))
float code(float cosTheta, float alpha) {
return 0.5f * ((alpha + 1.0f) * ((alpha + -1.0f) / (((float) M_PI) * logf(alpha))));
}
function code(cosTheta, alpha) return Float32(Float32(0.5) * Float32(Float32(alpha + Float32(1.0)) * Float32(Float32(alpha + Float32(-1.0)) / Float32(Float32(pi) * log(alpha))))) end
function tmp = code(cosTheta, alpha) tmp = single(0.5) * ((alpha + single(1.0)) * ((alpha + single(-1.0)) / (single(pi) * log(alpha)))); end
\begin{array}{l}
\\
0.5 \cdot \left(\left(\alpha + 1\right) \cdot \frac{\alpha + -1}{\pi \cdot \log \alpha}\right)
\end{array}
Initial program 98.6%
associate-/r*98.6%
fma-neg98.4%
metadata-eval98.4%
+-commutative98.4%
associate-*l*98.4%
fma-define98.4%
fma-neg98.4%
metadata-eval98.4%
Simplified98.4%
div-inv98.2%
fma-undefine98.4%
difference-of-sqr--198.1%
associate-*l*97.9%
sub-neg97.9%
metadata-eval97.9%
associate-/r*97.8%
pow297.8%
log-pow98.1%
Applied egg-rr98.1%
Taylor expanded in cosTheta around 0 95.0%
associate-/l*94.9%
sub-neg94.9%
metadata-eval94.9%
Applied egg-rr94.9%
Final simplification94.9%
(FPCore (cosTheta alpha) :precision binary32 (/ (/ -0.5 PI) (log alpha)))
float code(float cosTheta, float alpha) {
return (-0.5f / ((float) M_PI)) / logf(alpha);
}
function code(cosTheta, alpha) return Float32(Float32(Float32(-0.5) / Float32(pi)) / log(alpha)) end
function tmp = code(cosTheta, alpha) tmp = (single(-0.5) / single(pi)) / log(alpha); end
\begin{array}{l}
\\
\frac{\frac{-0.5}{\pi}}{\log \alpha}
\end{array}
Initial program 98.6%
associate-/r*98.6%
fma-neg98.4%
metadata-eval98.4%
+-commutative98.4%
associate-*l*98.4%
fma-define98.4%
fma-neg98.4%
metadata-eval98.4%
Simplified98.4%
div-inv98.2%
fma-undefine98.4%
difference-of-sqr--198.1%
associate-*l*97.9%
sub-neg97.9%
metadata-eval97.9%
associate-/r*97.8%
pow297.8%
log-pow98.1%
Applied egg-rr98.1%
Taylor expanded in cosTheta around 0 95.0%
Taylor expanded in alpha around 0 63.8%
Taylor expanded in alpha around 0 63.8%
associate-/r*63.8%
Simplified63.8%
(FPCore (cosTheta alpha) :precision binary32 (/ -0.5 (* PI (log alpha))))
float code(float cosTheta, float alpha) {
return -0.5f / (((float) M_PI) * logf(alpha));
}
function code(cosTheta, alpha) return Float32(Float32(-0.5) / Float32(Float32(pi) * log(alpha))) end
function tmp = code(cosTheta, alpha) tmp = single(-0.5) / (single(pi) * log(alpha)); end
\begin{array}{l}
\\
\frac{-0.5}{\pi \cdot \log \alpha}
\end{array}
Initial program 98.6%
associate-/r*98.6%
fma-neg98.4%
metadata-eval98.4%
+-commutative98.4%
associate-*l*98.4%
fma-define98.4%
fma-neg98.4%
metadata-eval98.4%
Simplified98.4%
div-inv98.2%
fma-undefine98.4%
difference-of-sqr--198.1%
associate-*l*97.9%
sub-neg97.9%
metadata-eval97.9%
associate-/r*97.8%
pow297.8%
log-pow98.1%
Applied egg-rr98.1%
Taylor expanded in cosTheta around 0 95.0%
Taylor expanded in alpha around 0 63.8%
Taylor expanded in alpha around 0 63.8%
herbie shell --seed 2024123
(FPCore (cosTheta alpha)
:name "GTR1 distribution"
:precision binary32
:pre (and (and (<= 0.0 cosTheta) (<= cosTheta 1.0)) (and (<= 0.0001 alpha) (<= alpha 1.0)))
(/ (- (* alpha alpha) 1.0) (* (* PI (log (* alpha alpha))) (+ 1.0 (* (* (- (* alpha alpha) 1.0) cosTheta) cosTheta)))))