
(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}
Herbie found 6 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 (- x -1.0)))) (/ 1.0 (fma (pow x 0.3333333333333333) (+ (cbrt x) t_0) (pow t_0 2.0)))))
double code(double x) {
double t_0 = cbrt((x - -1.0));
return 1.0 / fma(pow(x, 0.3333333333333333), (cbrt(x) + t_0), pow(t_0, 2.0));
}
function code(x) t_0 = cbrt(Float64(x - -1.0)) return Float64(1.0 / fma((x ^ 0.3333333333333333), Float64(cbrt(x) + t_0), (t_0 ^ 2.0))) end
code[x_] := Block[{t$95$0 = N[Power[N[(x - -1.0), $MachinePrecision], 1/3], $MachinePrecision]}, N[(1.0 / N[(N[Power[x, 0.3333333333333333], $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]{x - -1}\\
\frac{1}{\mathsf{fma}\left({x}^{0.3333333333333333}, \sqrt[3]{x} + t\_0, {t\_0}^{2}\right)}
\end{array}
\end{array}
Initial program 6.9%
lift--.f64N/A
flip3--N/A
lower-/.f64N/A
lift-cbrt.f64N/A
rem-cube-cbrtN/A
lift-cbrt.f64N/A
rem-cube-cbrtN/A
lower--.f64N/A
lift-+.f64N/A
metadata-evalN/A
fp-cancel-sign-sub-invN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower--.f64N/A
metadata-evalN/A
+-commutativeN/A
Applied rewrites9.0%
lift-cbrt.f64N/A
pow1/3N/A
lift-pow.f648.9
Applied rewrites8.9%
Taylor expanded in x around 0
Applied rewrites93.1%
(FPCore (x) :precision binary64 (if (<= x 6.4e+161) (* (cbrt (pow x -2.0)) 0.3333333333333333) (pow (fma (+ (cbrt x) 1.0) (cbrt x) 1.0) -1.0)))
double code(double x) {
double tmp;
if (x <= 6.4e+161) {
tmp = cbrt(pow(x, -2.0)) * 0.3333333333333333;
} else {
tmp = pow(fma((cbrt(x) + 1.0), cbrt(x), 1.0), -1.0);
}
return tmp;
}
function code(x) tmp = 0.0 if (x <= 6.4e+161) tmp = Float64(cbrt((x ^ -2.0)) * 0.3333333333333333); else tmp = fma(Float64(cbrt(x) + 1.0), cbrt(x), 1.0) ^ -1.0; end return tmp end
code[x_] := If[LessEqual[x, 6.4e+161], N[(N[Power[N[Power[x, -2.0], $MachinePrecision], 1/3], $MachinePrecision] * 0.3333333333333333), $MachinePrecision], N[Power[N[(N[(N[Power[x, 1/3], $MachinePrecision] + 1.0), $MachinePrecision] * N[Power[x, 1/3], $MachinePrecision] + 1.0), $MachinePrecision], -1.0], $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;x \leq 6.4 \cdot 10^{+161}:\\
\;\;\;\;\sqrt[3]{{x}^{-2}} \cdot 0.3333333333333333\\
\mathbf{else}:\\
\;\;\;\;{\left(\mathsf{fma}\left(\sqrt[3]{x} + 1, \sqrt[3]{x}, 1\right)\right)}^{-1}\\
\end{array}
\end{array}
if x < 6.40000000000000004e161Initial program 8.8%
lift-cbrt.f64N/A
lift-+.f64N/A
flip3-+N/A
cbrt-divN/A
lower-/.f64N/A
lower-cbrt.f64N/A
metadata-evalN/A
metadata-evalN/A
fp-cancel-sign-sub-invN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower--.f64N/A
lower-pow.f64N/A
metadata-evalN/A
lower-cbrt.f64N/A
lower-fma.f64N/A
metadata-evalN/A
*-rgt-identityN/A
lower--.f648.4
Applied rewrites8.4%
Taylor expanded in x around inf
*-commutativeN/A
lower-*.f64N/A
lower-cbrt.f64N/A
pow-flipN/A
metadata-evalN/A
lower-pow.f6493.3
Applied rewrites93.3%
if 6.40000000000000004e161 < x Initial program 4.8%
lift--.f64N/A
flip3--N/A
lower-/.f64N/A
lift-cbrt.f64N/A
rem-cube-cbrtN/A
lift-cbrt.f64N/A
rem-cube-cbrtN/A
lower--.f64N/A
lift-+.f64N/A
metadata-evalN/A
fp-cancel-sign-sub-invN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower--.f64N/A
metadata-evalN/A
+-commutativeN/A
Applied rewrites4.8%
lift-cbrt.f64N/A
pow1/3N/A
lift-pow.f644.8
Applied rewrites4.8%
Taylor expanded in x around 0
inv-powN/A
lower-pow.f64N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
+-commutativeN/A
lower-+.f64N/A
lift-cbrt.f64N/A
lift-cbrt.f6417.7
Applied rewrites17.7%
(FPCore (x) :precision binary64 (* (cbrt (pow x -2.0)) 0.3333333333333333))
double code(double x) {
return cbrt(pow(x, -2.0)) * 0.3333333333333333;
}
public static double code(double x) {
return Math.cbrt(Math.pow(x, -2.0)) * 0.3333333333333333;
}
function code(x) return Float64(cbrt((x ^ -2.0)) * 0.3333333333333333) end
code[x_] := N[(N[Power[N[Power[x, -2.0], $MachinePrecision], 1/3], $MachinePrecision] * 0.3333333333333333), $MachinePrecision]
\begin{array}{l}
\\
\sqrt[3]{{x}^{-2}} \cdot 0.3333333333333333
\end{array}
Initial program 6.9%
lift-cbrt.f64N/A
lift-+.f64N/A
flip3-+N/A
cbrt-divN/A
lower-/.f64N/A
lower-cbrt.f64N/A
metadata-evalN/A
metadata-evalN/A
fp-cancel-sign-sub-invN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower--.f64N/A
lower-pow.f64N/A
metadata-evalN/A
lower-cbrt.f64N/A
lower-fma.f64N/A
metadata-evalN/A
*-rgt-identityN/A
lower--.f644.5
Applied rewrites4.5%
Taylor expanded in x around inf
*-commutativeN/A
lower-*.f64N/A
lower-cbrt.f64N/A
pow-flipN/A
metadata-evalN/A
lower-pow.f6452.4
Applied rewrites52.4%
(FPCore (x) :precision binary64 (/ (- (- x -1.0) x) (* (cbrt (* x x)) 2.0)))
double code(double x) {
return ((x - -1.0) - x) / (cbrt((x * x)) * 2.0);
}
public static double code(double x) {
return ((x - -1.0) - x) / (Math.cbrt((x * x)) * 2.0);
}
function code(x) return Float64(Float64(Float64(x - -1.0) - x) / Float64(cbrt(Float64(x * x)) * 2.0)) end
code[x_] := N[(N[(N[(x - -1.0), $MachinePrecision] - x), $MachinePrecision] / N[(N[Power[N[(x * x), $MachinePrecision], 1/3], $MachinePrecision] * 2.0), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\left(x - -1\right) - x}{\sqrt[3]{x \cdot x} \cdot 2}
\end{array}
Initial program 6.9%
lift--.f64N/A
flip3--N/A
lower-/.f64N/A
lift-cbrt.f64N/A
rem-cube-cbrtN/A
lift-cbrt.f64N/A
rem-cube-cbrtN/A
lower--.f64N/A
lift-+.f64N/A
metadata-evalN/A
fp-cancel-sign-sub-invN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower--.f64N/A
metadata-evalN/A
+-commutativeN/A
Applied rewrites9.0%
lift-cbrt.f64N/A
pow1/3N/A
lift-pow.f648.9
Applied rewrites8.9%
Taylor expanded in x around inf
*-commutativeN/A
lower-*.f64N/A
lower-cbrt.f64N/A
pow2N/A
lower-*.f645.0
Applied rewrites5.0%
(FPCore (x) :precision binary64 (- (fma 0.3333333333333333 x 1.0) (cbrt x)))
double code(double x) {
return fma(0.3333333333333333, x, 1.0) - cbrt(x);
}
function code(x) return Float64(fma(0.3333333333333333, x, 1.0) - cbrt(x)) end
code[x_] := N[(N[(0.3333333333333333 * x + 1.0), $MachinePrecision] - N[Power[x, 1/3], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(0.3333333333333333, x, 1\right) - \sqrt[3]{x}
\end{array}
Initial program 6.9%
rem-cube-cbrtN/A
lift-cbrt.f64N/A
unpow3N/A
lower-*.f64N/A
pow2N/A
metadata-evalN/A
1-expN/A
1-expN/A
metadata-evalN/A
lower-pow.f64N/A
lift-+.f64N/A
metadata-evalN/A
fp-cancel-sign-sub-invN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower--.f64N/A
metadata-evalN/A
1-expN/A
metadata-evalN/A
1-expN/A
metadata-eval7.0
lift-+.f64N/A
metadata-evalN/A
fp-cancel-sign-sub-invN/A
Applied rewrites7.0%
lift-cbrt.f64N/A
lift-*.f64N/A
cbrt-prodN/A
lower-*.f64N/A
lower-cbrt.f64N/A
lower-cbrt.f647.0
Applied rewrites7.0%
lift-cbrt.f64N/A
pow1/3N/A
pow-to-expN/A
lower-exp.f64N/A
lower-*.f64N/A
lift-cbrt.f64N/A
pow1/3N/A
log-powN/A
lower-*.f64N/A
lift--.f64N/A
sub-negate1N/A
metadata-evalN/A
+-commutativeN/A
lower-log1p.f644.9
Applied rewrites4.9%
Taylor expanded in x around 0
+-commutativeN/A
lower-fma.f644.3
Applied rewrites4.3%
(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 6.9%
rem-cube-cbrtN/A
lift-cbrt.f64N/A
unpow3N/A
lower-*.f64N/A
pow2N/A
metadata-evalN/A
1-expN/A
1-expN/A
metadata-evalN/A
lower-pow.f64N/A
lift-+.f64N/A
metadata-evalN/A
fp-cancel-sign-sub-invN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower--.f64N/A
metadata-evalN/A
1-expN/A
metadata-evalN/A
1-expN/A
metadata-eval7.0
lift-+.f64N/A
metadata-evalN/A
fp-cancel-sign-sub-invN/A
Applied rewrites7.0%
lift-cbrt.f64N/A
lift-*.f64N/A
cbrt-prodN/A
lower-*.f64N/A
lower-cbrt.f64N/A
lower-cbrt.f647.0
Applied rewrites7.0%
lift-cbrt.f64N/A
pow1/3N/A
pow-to-expN/A
lower-exp.f64N/A
lower-*.f64N/A
lift-cbrt.f64N/A
pow1/3N/A
log-powN/A
lower-*.f64N/A
lift--.f64N/A
sub-negate1N/A
metadata-evalN/A
+-commutativeN/A
lower-log1p.f644.9
Applied rewrites4.9%
Taylor expanded in x around 0
Applied rewrites1.8%
(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 2025107
(FPCore (x)
:name "2cbrt (problem 3.3.4)"
:precision binary64
:pre (and (> x 1.0) (< x 1e+308))
:alt
(! :herbie-platform default (/ 1 (+ (* (cbrt (+ x 1)) (cbrt (+ x 1))) (* (cbrt x) (cbrt (+ x 1))) (* (cbrt x) (cbrt x)))))
(- (cbrt (+ x 1.0)) (cbrt x)))