
(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 6 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 (/ (* (* a -3.0) c) (* (* a 3.0) (+ b (sqrt (fma b b (* -3.0 (* a c))))))))
double code(double a, double b, double c) {
return ((a * -3.0) * c) / ((a * 3.0) * (b + sqrt(fma(b, b, (-3.0 * (a * c))))));
}
function code(a, b, c) return Float64(Float64(Float64(a * -3.0) * c) / Float64(Float64(a * 3.0) * Float64(b + sqrt(fma(b, b, Float64(-3.0 * Float64(a * c))))))) end
code[a_, b_, c_] := N[(N[(N[(a * -3.0), $MachinePrecision] * c), $MachinePrecision] / N[(N[(a * 3.0), $MachinePrecision] * N[(b + N[Sqrt[N[(b * b + N[(-3.0 * N[(a * c), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\left(a \cdot -3\right) \cdot c}{\left(a \cdot 3\right) \cdot \left(b + \sqrt{\mathsf{fma}\left(b, b, -3 \cdot \left(a \cdot c\right)\right)}\right)}
\end{array}
Initial program 18.1%
Applied rewrites18.4%
lift-/.f64N/A
lift--.f64N/A
lift-/.f64N/A
lift-/.f64N/A
sub-divN/A
associate-/l/N/A
lower-/.f64N/A
Applied rewrites18.7%
lift--.f64N/A
lift-fma.f64N/A
lift-*.f64N/A
+-commutativeN/A
associate--l+N/A
lift-*.f64N/A
lift-*.f64N/A
associate-*r*N/A
metadata-evalN/A
distribute-lft-neg-inN/A
lower-fma.f64N/A
*-commutativeN/A
distribute-rgt-neg-inN/A
metadata-evalN/A
lower-*.f64N/A
lower--.f6499.4
Applied rewrites99.4%
lift-fma.f64N/A
lift--.f64N/A
+-inversesN/A
+-rgt-identityN/A
lower-*.f6499.4
Applied rewrites99.4%
(FPCore (a b c) :precision binary64 (let* ((t_0 (* -3.0 (* a c)))) (/ t_0 (* (* a 3.0) (+ b (sqrt (fma b b t_0)))))))
double code(double a, double b, double c) {
double t_0 = -3.0 * (a * c);
return t_0 / ((a * 3.0) * (b + sqrt(fma(b, b, t_0))));
}
function code(a, b, c) t_0 = Float64(-3.0 * Float64(a * c)) return Float64(t_0 / Float64(Float64(a * 3.0) * Float64(b + sqrt(fma(b, b, t_0))))) end
code[a_, b_, c_] := Block[{t$95$0 = N[(-3.0 * N[(a * c), $MachinePrecision]), $MachinePrecision]}, N[(t$95$0 / N[(N[(a * 3.0), $MachinePrecision] * N[(b + N[Sqrt[N[(b * b + t$95$0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := -3 \cdot \left(a \cdot c\right)\\
\frac{t\_0}{\left(a \cdot 3\right) \cdot \left(b + \sqrt{\mathsf{fma}\left(b, b, t\_0\right)}\right)}
\end{array}
\end{array}
Initial program 17.5%
Applied rewrites17.7%
lift-/.f64N/A
lift--.f64N/A
lift-/.f64N/A
lift-/.f64N/A
sub-divN/A
associate-/l/N/A
lower-/.f64N/A
Applied rewrites17.9%
Taylor expanded in b around 0
rem-square-sqrtN/A
unpow2N/A
lower-*.f64N/A
unpow2N/A
rem-square-sqrtN/A
lower-*.f6499.2
Applied rewrites99.2%
herbie shell --seed 2024219
(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)))