
(FPCore (x) :precision binary64 (- (cbrt (+ x 1.0)) (cbrt x)))
double code(double x) {
return cbrt((x + 1.0)) - cbrt(x);
}
public static double code(double x) {
return Math.cbrt((x + 1.0)) - Math.cbrt(x);
}
function code(x) return Float64(cbrt(Float64(x + 1.0)) - cbrt(x)) end
code[x_] := N[(N[Power[N[(x + 1.0), $MachinePrecision], 1/3], $MachinePrecision] - N[Power[x, 1/3], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\sqrt[3]{x + 1} - \sqrt[3]{x}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 8 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (x) :precision binary64 (- (cbrt (+ x 1.0)) (cbrt x)))
double code(double x) {
return cbrt((x + 1.0)) - cbrt(x);
}
public static double code(double x) {
return Math.cbrt((x + 1.0)) - Math.cbrt(x);
}
function code(x) return Float64(cbrt(Float64(x + 1.0)) - cbrt(x)) end
code[x_] := N[(N[Power[N[(x + 1.0), $MachinePrecision], 1/3], $MachinePrecision] - N[Power[x, 1/3], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\sqrt[3]{x + 1} - \sqrt[3]{x}
\end{array}
(FPCore (x) :precision binary64 (let* ((t_0 (cbrt (+ 1.0 x)))) (/ 1.0 (fma (cbrt x) (+ (cbrt x) t_0) (pow t_0 2.0)))))
double code(double x) {
double t_0 = cbrt((1.0 + x));
return 1.0 / fma(cbrt(x), (cbrt(x) + t_0), pow(t_0, 2.0));
}
function code(x) t_0 = cbrt(Float64(1.0 + x)) return Float64(1.0 / fma(cbrt(x), Float64(cbrt(x) + t_0), (t_0 ^ 2.0))) end
code[x_] := Block[{t$95$0 = N[Power[N[(1.0 + x), $MachinePrecision], 1/3], $MachinePrecision]}, N[(1.0 / N[(N[Power[x, 1/3], $MachinePrecision] * N[(N[Power[x, 1/3], $MachinePrecision] + t$95$0), $MachinePrecision] + N[Power[t$95$0, 2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt[3]{1 + x}\\
\frac{1}{\mathsf{fma}\left(\sqrt[3]{x}, \sqrt[3]{x} + t\_0, {t\_0}^{2}\right)}
\end{array}
\end{array}
Initial program 6.0%
flip3--6.2%
div-inv6.2%
rem-cube-cbrt5.3%
rem-cube-cbrt7.5%
+-commutative7.5%
distribute-rgt-out7.5%
+-commutative7.5%
fma-define7.5%
add-exp-log7.5%
Applied egg-rr7.5%
associate-*r/7.5%
*-rgt-identity7.5%
+-commutative7.5%
associate--l+93.2%
+-inverses93.2%
metadata-eval93.2%
+-commutative93.2%
exp-prod92.3%
Simplified92.3%
add-sqr-sqrt92.3%
unpow-prod-down93.9%
Applied egg-rr93.9%
add-sqr-sqrt93.9%
pow293.9%
sqrt-prod93.9%
add-exp-log93.3%
add-sqr-sqrt93.3%
log-pow93.2%
log1p-undefine93.2%
+-commutative93.2%
pow1/293.2%
log-pow93.2%
rem-log-exp93.2%
metadata-eval93.2%
pow-to-exp93.0%
pow1/398.5%
Applied egg-rr98.5%
Final simplification98.5%
(FPCore (x) :precision binary64 (/ 1.0 (fma (cbrt x) (+ (cbrt x) (cbrt (+ 1.0 x))) (pow (cbrt x) 2.0))))
double code(double x) {
return 1.0 / fma(cbrt(x), (cbrt(x) + cbrt((1.0 + x))), pow(cbrt(x), 2.0));
}
function code(x) return Float64(1.0 / fma(cbrt(x), Float64(cbrt(x) + cbrt(Float64(1.0 + x))), (cbrt(x) ^ 2.0))) end
code[x_] := N[(1.0 / N[(N[Power[x, 1/3], $MachinePrecision] * N[(N[Power[x, 1/3], $MachinePrecision] + N[Power[N[(1.0 + x), $MachinePrecision], 1/3], $MachinePrecision]), $MachinePrecision] + N[Power[N[Power[x, 1/3], $MachinePrecision], 2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{1}{\mathsf{fma}\left(\sqrt[3]{x}, \sqrt[3]{x} + \sqrt[3]{1 + x}, {\left(\sqrt[3]{x}\right)}^{2}\right)}
\end{array}
Initial program 6.0%
flip3--6.2%
div-inv6.2%
rem-cube-cbrt5.3%
rem-cube-cbrt7.5%
+-commutative7.5%
distribute-rgt-out7.5%
+-commutative7.5%
fma-define7.5%
add-exp-log7.5%
Applied egg-rr7.5%
associate-*r/7.5%
*-rgt-identity7.5%
+-commutative7.5%
associate--l+93.2%
+-inverses93.2%
metadata-eval93.2%
+-commutative93.2%
exp-prod92.3%
Simplified92.3%
add-sqr-sqrt92.3%
unpow-prod-down93.9%
Applied egg-rr93.9%
add-sqr-sqrt93.9%
pow293.9%
sqrt-prod93.9%
add-exp-log93.3%
add-sqr-sqrt93.3%
log-pow93.2%
log1p-undefine93.2%
+-commutative93.2%
pow1/293.2%
log-pow93.2%
rem-log-exp93.2%
metadata-eval93.2%
pow-to-exp93.0%
pow1/398.5%
Applied egg-rr98.5%
Taylor expanded in x around inf 97.3%
Final simplification97.3%
(FPCore (x) :precision binary64 (/ 1.0 (fma (cbrt x) (+ (cbrt x) (cbrt (+ 1.0 x))) (pow (+ 1.0 x) 0.6666666666666666))))
double code(double x) {
return 1.0 / fma(cbrt(x), (cbrt(x) + cbrt((1.0 + x))), pow((1.0 + x), 0.6666666666666666));
}
function code(x) return Float64(1.0 / fma(cbrt(x), Float64(cbrt(x) + cbrt(Float64(1.0 + x))), (Float64(1.0 + x) ^ 0.6666666666666666))) end
code[x_] := N[(1.0 / N[(N[Power[x, 1/3], $MachinePrecision] * N[(N[Power[x, 1/3], $MachinePrecision] + N[Power[N[(1.0 + x), $MachinePrecision], 1/3], $MachinePrecision]), $MachinePrecision] + N[Power[N[(1.0 + x), $MachinePrecision], 0.6666666666666666], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{1}{\mathsf{fma}\left(\sqrt[3]{x}, \sqrt[3]{x} + \sqrt[3]{1 + x}, {\left(1 + x\right)}^{0.6666666666666666}\right)}
\end{array}
Initial program 6.0%
flip3--6.2%
div-inv6.2%
rem-cube-cbrt5.3%
rem-cube-cbrt7.5%
+-commutative7.5%
distribute-rgt-out7.5%
+-commutative7.5%
fma-define7.5%
add-exp-log7.5%
Applied egg-rr7.5%
associate-*r/7.5%
*-rgt-identity7.5%
+-commutative7.5%
associate--l+93.2%
+-inverses93.2%
metadata-eval93.2%
+-commutative93.2%
exp-prod92.3%
Simplified92.3%
add-sqr-sqrt92.3%
unpow-prod-down93.9%
Applied egg-rr93.9%
add-sqr-sqrt93.9%
pow293.9%
sqrt-prod93.9%
add-exp-log93.3%
add-sqr-sqrt93.3%
log-pow93.2%
log1p-undefine93.2%
+-commutative93.2%
pow1/293.2%
log-pow93.2%
rem-log-exp93.2%
metadata-eval93.2%
pow-to-exp93.0%
pow1/398.5%
Applied egg-rr93.0%
Final simplification93.0%
(FPCore (x)
:precision binary64
(if (<= x 1.35e+154)
(/
(+
(* (cbrt x) -0.1111111111111111)
(* 0.3333333333333333 (pow (cbrt x) 4.0)))
(pow x 2.0))
(/ 1.0 (fma (cbrt x) (+ (cbrt x) (cbrt (+ 1.0 x))) 1.0))))
double code(double x) {
double tmp;
if (x <= 1.35e+154) {
tmp = ((cbrt(x) * -0.1111111111111111) + (0.3333333333333333 * pow(cbrt(x), 4.0))) / pow(x, 2.0);
} else {
tmp = 1.0 / fma(cbrt(x), (cbrt(x) + cbrt((1.0 + x))), 1.0);
}
return tmp;
}
function code(x) tmp = 0.0 if (x <= 1.35e+154) tmp = Float64(Float64(Float64(cbrt(x) * -0.1111111111111111) + Float64(0.3333333333333333 * (cbrt(x) ^ 4.0))) / (x ^ 2.0)); else tmp = Float64(1.0 / fma(cbrt(x), Float64(cbrt(x) + cbrt(Float64(1.0 + x))), 1.0)); end return tmp end
code[x_] := If[LessEqual[x, 1.35e+154], N[(N[(N[(N[Power[x, 1/3], $MachinePrecision] * -0.1111111111111111), $MachinePrecision] + N[(0.3333333333333333 * N[Power[N[Power[x, 1/3], $MachinePrecision], 4.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[Power[x, 2.0], $MachinePrecision]), $MachinePrecision], N[(1.0 / N[(N[Power[x, 1/3], $MachinePrecision] * N[(N[Power[x, 1/3], $MachinePrecision] + N[Power[N[(1.0 + x), $MachinePrecision], 1/3], $MachinePrecision]), $MachinePrecision] + 1.0), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;x \leq 1.35 \cdot 10^{+154}:\\
\;\;\;\;\frac{\sqrt[3]{x} \cdot -0.1111111111111111 + 0.3333333333333333 \cdot {\left(\sqrt[3]{x}\right)}^{4}}{{x}^{2}}\\
\mathbf{else}:\\
\;\;\;\;\frac{1}{\mathsf{fma}\left(\sqrt[3]{x}, \sqrt[3]{x} + \sqrt[3]{1 + x}, 1\right)}\\
\end{array}
\end{array}
if x < 1.35000000000000003e154Initial program 7.2%
Taylor expanded in x around inf 43.9%
sqr-pow44.0%
cbrt-prod97.1%
metadata-eval97.1%
pow297.1%
metadata-eval97.1%
pow297.1%
cbrt-unprod97.1%
cbrt-unprod96.6%
pow296.6%
pow296.6%
Applied egg-rr96.6%
pow-sqr96.6%
metadata-eval96.6%
Simplified96.6%
if 1.35000000000000003e154 < x Initial program 4.7%
flip3--4.7%
div-inv4.7%
rem-cube-cbrt3.2%
rem-cube-cbrt4.7%
+-commutative4.7%
distribute-rgt-out4.7%
+-commutative4.7%
fma-define4.7%
add-exp-log4.7%
Applied egg-rr4.7%
associate-*r/4.7%
*-rgt-identity4.7%
+-commutative4.7%
associate--l+92.0%
+-inverses92.0%
metadata-eval92.0%
+-commutative92.0%
exp-prod90.9%
Simplified90.9%
Taylor expanded in x around 0 20.0%
Final simplification58.6%
(FPCore (x) :precision binary64 (if (<= x 1.35e+154) (* 0.3333333333333333 (cbrt (/ 1.0 (pow x 2.0)))) (/ 1.0 (fma (cbrt x) (+ (cbrt x) (cbrt (+ 1.0 x))) 1.0))))
double code(double x) {
double tmp;
if (x <= 1.35e+154) {
tmp = 0.3333333333333333 * cbrt((1.0 / pow(x, 2.0)));
} else {
tmp = 1.0 / fma(cbrt(x), (cbrt(x) + cbrt((1.0 + x))), 1.0);
}
return tmp;
}
function code(x) tmp = 0.0 if (x <= 1.35e+154) tmp = Float64(0.3333333333333333 * cbrt(Float64(1.0 / (x ^ 2.0)))); else tmp = Float64(1.0 / fma(cbrt(x), Float64(cbrt(x) + cbrt(Float64(1.0 + x))), 1.0)); end return tmp end
code[x_] := If[LessEqual[x, 1.35e+154], N[(0.3333333333333333 * N[Power[N[(1.0 / N[Power[x, 2.0], $MachinePrecision]), $MachinePrecision], 1/3], $MachinePrecision]), $MachinePrecision], N[(1.0 / N[(N[Power[x, 1/3], $MachinePrecision] * N[(N[Power[x, 1/3], $MachinePrecision] + N[Power[N[(1.0 + x), $MachinePrecision], 1/3], $MachinePrecision]), $MachinePrecision] + 1.0), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;x \leq 1.35 \cdot 10^{+154}:\\
\;\;\;\;0.3333333333333333 \cdot \sqrt[3]{\frac{1}{{x}^{2}}}\\
\mathbf{else}:\\
\;\;\;\;\frac{1}{\mathsf{fma}\left(\sqrt[3]{x}, \sqrt[3]{x} + \sqrt[3]{1 + x}, 1\right)}\\
\end{array}
\end{array}
if x < 1.35000000000000003e154Initial program 7.2%
Taylor expanded in x around inf 96.4%
if 1.35000000000000003e154 < x Initial program 4.7%
flip3--4.7%
div-inv4.7%
rem-cube-cbrt3.2%
rem-cube-cbrt4.7%
+-commutative4.7%
distribute-rgt-out4.7%
+-commutative4.7%
fma-define4.7%
add-exp-log4.7%
Applied egg-rr4.7%
associate-*r/4.7%
*-rgt-identity4.7%
+-commutative4.7%
associate--l+92.0%
+-inverses92.0%
metadata-eval92.0%
+-commutative92.0%
exp-prod90.9%
Simplified90.9%
Taylor expanded in x around 0 20.0%
Final simplification58.5%
(FPCore (x) :precision binary64 (* 0.3333333333333333 (cbrt (/ 1.0 (pow x 2.0)))))
double code(double x) {
return 0.3333333333333333 * cbrt((1.0 / pow(x, 2.0)));
}
public static double code(double x) {
return 0.3333333333333333 * Math.cbrt((1.0 / Math.pow(x, 2.0)));
}
function code(x) return Float64(0.3333333333333333 * cbrt(Float64(1.0 / (x ^ 2.0)))) end
code[x_] := N[(0.3333333333333333 * N[Power[N[(1.0 / N[Power[x, 2.0], $MachinePrecision]), $MachinePrecision], 1/3], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
0.3333333333333333 \cdot \sqrt[3]{\frac{1}{{x}^{2}}}
\end{array}
Initial program 6.0%
Taylor expanded in x around inf 50.9%
(FPCore (x) :precision binary64 (- (cbrt (+ 1.0 x)) (cbrt x)))
double code(double x) {
return cbrt((1.0 + x)) - cbrt(x);
}
public static double code(double x) {
return Math.cbrt((1.0 + x)) - Math.cbrt(x);
}
function code(x) return Float64(cbrt(Float64(1.0 + x)) - cbrt(x)) end
code[x_] := N[(N[Power[N[(1.0 + x), $MachinePrecision], 1/3], $MachinePrecision] - N[Power[x, 1/3], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\sqrt[3]{1 + x} - \sqrt[3]{x}
\end{array}
Initial program 6.0%
Final simplification6.0%
(FPCore (x) :precision binary64 (+ 1.0 (cbrt x)))
double code(double x) {
return 1.0 + cbrt(x);
}
public static double code(double x) {
return 1.0 + Math.cbrt(x);
}
function code(x) return Float64(1.0 + cbrt(x)) end
code[x_] := N[(1.0 + N[Power[x, 1/3], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
1 + \sqrt[3]{x}
\end{array}
Initial program 6.0%
Taylor expanded in x around 0 1.8%
sub-neg1.8%
rem-square-sqrt0.0%
fabs-sqr0.0%
rem-square-sqrt5.3%
fabs-neg5.3%
unpow1/35.3%
metadata-eval5.3%
pow-sqr5.3%
fabs-sqr5.3%
pow-sqr5.3%
metadata-eval5.3%
unpow1/35.3%
Simplified5.3%
(FPCore (x) :precision binary64 (let* ((t_0 (cbrt (+ x 1.0)))) (/ 1.0 (+ (+ (* t_0 t_0) (* (cbrt x) t_0)) (* (cbrt x) (cbrt x))))))
double code(double x) {
double t_0 = cbrt((x + 1.0));
return 1.0 / (((t_0 * t_0) + (cbrt(x) * t_0)) + (cbrt(x) * cbrt(x)));
}
public static double code(double x) {
double t_0 = Math.cbrt((x + 1.0));
return 1.0 / (((t_0 * t_0) + (Math.cbrt(x) * t_0)) + (Math.cbrt(x) * Math.cbrt(x)));
}
function code(x) t_0 = cbrt(Float64(x + 1.0)) return Float64(1.0 / Float64(Float64(Float64(t_0 * t_0) + Float64(cbrt(x) * t_0)) + Float64(cbrt(x) * cbrt(x)))) end
code[x_] := Block[{t$95$0 = N[Power[N[(x + 1.0), $MachinePrecision], 1/3], $MachinePrecision]}, N[(1.0 / N[(N[(N[(t$95$0 * t$95$0), $MachinePrecision] + N[(N[Power[x, 1/3], $MachinePrecision] * t$95$0), $MachinePrecision]), $MachinePrecision] + N[(N[Power[x, 1/3], $MachinePrecision] * N[Power[x, 1/3], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt[3]{x + 1}\\
\frac{1}{\left(t\_0 \cdot t\_0 + \sqrt[3]{x} \cdot t\_0\right) + \sqrt[3]{x} \cdot \sqrt[3]{x}}
\end{array}
\end{array}
herbie shell --seed 2024096
(FPCore (x)
:name "2cbrt (problem 3.3.4)"
:precision binary64
:pre (and (> x 1.0) (< x 1e+308))
:alt
(/ 1.0 (+ (+ (* (cbrt (+ x 1.0)) (cbrt (+ x 1.0))) (* (cbrt x) (cbrt (+ x 1.0)))) (* (cbrt x) (cbrt x))))
(- (cbrt (+ x 1.0)) (cbrt x)))