
(FPCore (a b c) :precision binary64 (/ (+ (- b) (sqrt (- (* b b) (* (* 3.0 a) c)))) (* 3.0 a)))
double code(double a, double b, double c) {
return (-b + sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a);
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
code = (-b + sqrt(((b * b) - ((3.0d0 * a) * c)))) / (3.0d0 * a)
end function
public static double code(double a, double b, double c) {
return (-b + Math.sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a);
}
def code(a, b, c): return (-b + math.sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a)
function code(a, b, c) return Float64(Float64(Float64(-b) + sqrt(Float64(Float64(b * b) - Float64(Float64(3.0 * a) * c)))) / Float64(3.0 * a)) end
function tmp = code(a, b, c) tmp = (-b + sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a); end
code[a_, b_, c_] := N[(N[((-b) + N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(N[(3.0 * a), $MachinePrecision] * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(3.0 * a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 5 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (a b c) :precision binary64 (/ (+ (- b) (sqrt (- (* b b) (* (* 3.0 a) c)))) (* 3.0 a)))
double code(double a, double b, double c) {
return (-b + sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a);
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
code = (-b + sqrt(((b * b) - ((3.0d0 * a) * c)))) / (3.0d0 * a)
end function
public static double code(double a, double b, double c) {
return (-b + Math.sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a);
}
def code(a, b, c): return (-b + math.sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a)
function code(a, b, c) return Float64(Float64(Float64(-b) + sqrt(Float64(Float64(b * b) - Float64(Float64(3.0 * a) * c)))) / Float64(3.0 * a)) end
function tmp = code(a, b, c) tmp = (-b + sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a); end
code[a_, b_, c_] := N[(N[((-b) + N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(N[(3.0 * a), $MachinePrecision] * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(3.0 * a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}
\end{array}
(FPCore (a b c)
:precision binary64
(let* ((t_0 (* (* c c) (* (* a a) -1.125))))
(fma
-0.5625
(/ (* (pow c 3.0) (* a a)) (pow b 5.0))
(fma
-0.16666666666666666
(/ (+ (* t_0 t_0) (* 5.0625 (pow (* c a) 4.0))) (* a (pow b 7.0)))
(fma -0.5 (/ c b) (* -0.375 (/ (* c c) (/ (pow b 3.0) a))))))))
double code(double a, double b, double c) {
double t_0 = (c * c) * ((a * a) * -1.125);
return fma(-0.5625, ((pow(c, 3.0) * (a * a)) / pow(b, 5.0)), fma(-0.16666666666666666, (((t_0 * t_0) + (5.0625 * pow((c * a), 4.0))) / (a * pow(b, 7.0))), fma(-0.5, (c / b), (-0.375 * ((c * c) / (pow(b, 3.0) / a))))));
}
function code(a, b, c) t_0 = Float64(Float64(c * c) * Float64(Float64(a * a) * -1.125)) return fma(-0.5625, Float64(Float64((c ^ 3.0) * Float64(a * a)) / (b ^ 5.0)), fma(-0.16666666666666666, Float64(Float64(Float64(t_0 * t_0) + Float64(5.0625 * (Float64(c * a) ^ 4.0))) / Float64(a * (b ^ 7.0))), fma(-0.5, Float64(c / b), Float64(-0.375 * Float64(Float64(c * c) / Float64((b ^ 3.0) / a)))))) end
code[a_, b_, c_] := Block[{t$95$0 = N[(N[(c * c), $MachinePrecision] * N[(N[(a * a), $MachinePrecision] * -1.125), $MachinePrecision]), $MachinePrecision]}, N[(-0.5625 * N[(N[(N[Power[c, 3.0], $MachinePrecision] * N[(a * a), $MachinePrecision]), $MachinePrecision] / N[Power[b, 5.0], $MachinePrecision]), $MachinePrecision] + N[(-0.16666666666666666 * N[(N[(N[(t$95$0 * t$95$0), $MachinePrecision] + N[(5.0625 * N[Power[N[(c * a), $MachinePrecision], 4.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(a * N[Power[b, 7.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(-0.5 * N[(c / b), $MachinePrecision] + N[(-0.375 * N[(N[(c * c), $MachinePrecision] / N[(N[Power[b, 3.0], $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(c \cdot c\right) \cdot \left(\left(a \cdot a\right) \cdot -1.125\right)\\
\mathsf{fma}\left(-0.5625, \frac{{c}^{3} \cdot \left(a \cdot a\right)}{{b}^{5}}, \mathsf{fma}\left(-0.16666666666666666, \frac{t_0 \cdot t_0 + 5.0625 \cdot {\left(c \cdot a\right)}^{4}}{a \cdot {b}^{7}}, \mathsf{fma}\left(-0.5, \frac{c}{b}, -0.375 \cdot \frac{c \cdot c}{\frac{{b}^{3}}{a}}\right)\right)\right)
\end{array}
\end{array}
Initial program 20.5%
/-rgt-identity20.5%
metadata-eval20.5%
associate-/l*20.5%
associate-*r/20.5%
*-commutative20.5%
associate-*l/20.5%
associate-*r/20.5%
metadata-eval20.5%
metadata-eval20.5%
times-frac20.5%
neg-mul-120.5%
distribute-rgt-neg-in20.5%
times-frac20.5%
metadata-eval20.5%
neg-mul-120.5%
Simplified20.5%
Taylor expanded in b around inf 98.0%
fma-def98.0%
unpow298.0%
fma-def98.0%
Simplified98.0%
pow198.0%
pow-prod-down98.0%
Applied egg-rr98.0%
unpow198.0%
Simplified98.0%
unpow298.0%
associate-*l*98.0%
associate-*l*98.0%
Applied egg-rr98.0%
Final simplification98.0%
(FPCore (a b c) :precision binary64 (fma -0.5625 (/ (pow c 3.0) (/ (pow b 5.0) (* a a))) (fma -0.375 (/ (* c c) (/ (pow b 3.0) a)) (/ (* c -0.5) b))))
double code(double a, double b, double c) {
return fma(-0.5625, (pow(c, 3.0) / (pow(b, 5.0) / (a * a))), fma(-0.375, ((c * c) / (pow(b, 3.0) / a)), ((c * -0.5) / b)));
}
function code(a, b, c) return fma(-0.5625, Float64((c ^ 3.0) / Float64((b ^ 5.0) / Float64(a * a))), fma(-0.375, Float64(Float64(c * c) / Float64((b ^ 3.0) / a)), Float64(Float64(c * -0.5) / b))) end
code[a_, b_, c_] := N[(-0.5625 * N[(N[Power[c, 3.0], $MachinePrecision] / N[(N[Power[b, 5.0], $MachinePrecision] / N[(a * a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(-0.375 * N[(N[(c * c), $MachinePrecision] / N[(N[Power[b, 3.0], $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision] + N[(N[(c * -0.5), $MachinePrecision] / b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(-0.5625, \frac{{c}^{3}}{\frac{{b}^{5}}{a \cdot a}}, \mathsf{fma}\left(-0.375, \frac{c \cdot c}{\frac{{b}^{3}}{a}}, \frac{c \cdot -0.5}{b}\right)\right)
\end{array}
Initial program 20.5%
/-rgt-identity20.5%
metadata-eval20.5%
associate-/l*20.5%
associate-*r/20.5%
*-commutative20.5%
associate-*l/20.5%
associate-*r/20.5%
metadata-eval20.5%
metadata-eval20.5%
times-frac20.5%
neg-mul-120.5%
distribute-rgt-neg-in20.5%
times-frac20.5%
metadata-eval20.5%
neg-mul-120.5%
Simplified20.5%
Taylor expanded in b around inf 97.2%
fma-def97.2%
associate-/l*97.2%
unpow297.2%
+-commutative97.2%
fma-def97.2%
associate-/l*97.2%
unpow297.2%
associate-*r/97.2%
Simplified97.2%
Final simplification97.2%
(FPCore (a b c) :precision binary64 (* -0.3333333333333333 (fma 1.6875 (/ (pow c 3.0) (/ (pow b 5.0) (* a a))) (+ (* (/ c b) 1.5) (* 1.125 (* a (/ (* c c) (pow b 3.0))))))))
double code(double a, double b, double c) {
return -0.3333333333333333 * fma(1.6875, (pow(c, 3.0) / (pow(b, 5.0) / (a * a))), (((c / b) * 1.5) + (1.125 * (a * ((c * c) / pow(b, 3.0))))));
}
function code(a, b, c) return Float64(-0.3333333333333333 * fma(1.6875, Float64((c ^ 3.0) / Float64((b ^ 5.0) / Float64(a * a))), Float64(Float64(Float64(c / b) * 1.5) + Float64(1.125 * Float64(a * Float64(Float64(c * c) / (b ^ 3.0))))))) end
code[a_, b_, c_] := N[(-0.3333333333333333 * N[(1.6875 * N[(N[Power[c, 3.0], $MachinePrecision] / N[(N[Power[b, 5.0], $MachinePrecision] / N[(a * a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(N[(N[(c / b), $MachinePrecision] * 1.5), $MachinePrecision] + N[(1.125 * N[(a * N[(N[(c * c), $MachinePrecision] / N[Power[b, 3.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
-0.3333333333333333 \cdot \mathsf{fma}\left(1.6875, \frac{{c}^{3}}{\frac{{b}^{5}}{a \cdot a}}, \frac{c}{b} \cdot 1.5 + 1.125 \cdot \left(a \cdot \frac{c \cdot c}{{b}^{3}}\right)\right)
\end{array}
Initial program 20.5%
/-rgt-identity20.5%
metadata-eval20.5%
associate-/l*20.5%
associate-*r/20.5%
*-commutative20.5%
associate-*l/20.5%
associate-*r/20.5%
metadata-eval20.5%
metadata-eval20.5%
times-frac20.5%
neg-mul-120.5%
distribute-rgt-neg-in20.5%
times-frac20.5%
metadata-eval20.5%
neg-mul-120.5%
Simplified20.5%
Taylor expanded in b around inf 96.7%
fma-def96.7%
associate-/l*96.7%
unpow296.7%
+-commutative96.7%
fma-def97.0%
associate-/l*97.0%
unpow297.0%
Simplified97.0%
fma-udef96.7%
associate-/r/96.7%
Applied egg-rr96.7%
Final simplification96.7%
(FPCore (a b c) :precision binary64 (fma -0.375 (/ (* c c) (/ (pow b 3.0) a)) (/ (* c -0.5) b)))
double code(double a, double b, double c) {
return fma(-0.375, ((c * c) / (pow(b, 3.0) / a)), ((c * -0.5) / b));
}
function code(a, b, c) return fma(-0.375, Float64(Float64(c * c) / Float64((b ^ 3.0) / a)), Float64(Float64(c * -0.5) / b)) end
code[a_, b_, c_] := N[(-0.375 * N[(N[(c * c), $MachinePrecision] / N[(N[Power[b, 3.0], $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision] + N[(N[(c * -0.5), $MachinePrecision] / b), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(-0.375, \frac{c \cdot c}{\frac{{b}^{3}}{a}}, \frac{c \cdot -0.5}{b}\right)
\end{array}
Initial program 20.5%
/-rgt-identity20.5%
metadata-eval20.5%
associate-/l*20.5%
associate-*r/20.5%
*-commutative20.5%
associate-*l/20.5%
associate-*r/20.5%
metadata-eval20.5%
metadata-eval20.5%
times-frac20.5%
neg-mul-120.5%
distribute-rgt-neg-in20.5%
times-frac20.5%
metadata-eval20.5%
neg-mul-120.5%
Simplified20.5%
Taylor expanded in b around inf 95.3%
+-commutative95.3%
fma-def95.3%
associate-/l*95.3%
unpow295.3%
associate-*r/95.3%
Simplified95.3%
Final simplification95.3%
(FPCore (a b c) :precision binary64 (/ (* c -0.5) b))
double code(double a, double b, double c) {
return (c * -0.5) / b;
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
code = (c * (-0.5d0)) / b
end function
public static double code(double a, double b, double c) {
return (c * -0.5) / b;
}
def code(a, b, c): return (c * -0.5) / b
function code(a, b, c) return Float64(Float64(c * -0.5) / b) end
function tmp = code(a, b, c) tmp = (c * -0.5) / b; end
code[a_, b_, c_] := N[(N[(c * -0.5), $MachinePrecision] / b), $MachinePrecision]
\begin{array}{l}
\\
\frac{c \cdot -0.5}{b}
\end{array}
Initial program 20.5%
/-rgt-identity20.5%
metadata-eval20.5%
associate-/l*20.5%
associate-*r/20.5%
*-commutative20.5%
associate-*l/20.5%
associate-*r/20.5%
metadata-eval20.5%
metadata-eval20.5%
times-frac20.5%
neg-mul-120.5%
distribute-rgt-neg-in20.5%
times-frac20.5%
metadata-eval20.5%
neg-mul-120.5%
Simplified20.5%
Taylor expanded in b around inf 88.9%
associate-*r/88.9%
Simplified88.9%
Final simplification88.9%
herbie shell --seed 2023199
(FPCore (a b c)
:name "Cubic critical, wide range"
:precision binary64
:pre (and (and (and (< 4.930380657631324e-32 a) (< a 2.028240960365167e+31)) (and (< 4.930380657631324e-32 b) (< b 2.028240960365167e+31))) (and (< 4.930380657631324e-32 c) (< c 2.028240960365167e+31)))
(/ (+ (- b) (sqrt (- (* b b) (* (* 3.0 a) c)))) (* 3.0 a)))