
(FPCore (a b c) :precision binary64 (/ (+ (- b) (sqrt (- (* b b) (* (* 4.0 a) c)))) (* 2.0 a)))
double code(double a, double b, double c) {
return (-b + sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * 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) - ((4.0d0 * a) * c)))) / (2.0d0 * a)
end function
public static double code(double a, double b, double c) {
return (-b + Math.sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * a);
}
def code(a, b, c): return (-b + math.sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * a)
function code(a, b, c) return Float64(Float64(Float64(-b) + sqrt(Float64(Float64(b * b) - Float64(Float64(4.0 * a) * c)))) / Float64(2.0 * a)) end
function tmp = code(a, b, c) tmp = (-b + sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * a); end
code[a_, b_, c_] := N[(N[((-b) + N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(N[(4.0 * a), $MachinePrecision] * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(2.0 * a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 8 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (a b c) :precision binary64 (/ (+ (- b) (sqrt (- (* b b) (* (* 4.0 a) c)))) (* 2.0 a)))
double code(double a, double b, double c) {
return (-b + sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * 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) - ((4.0d0 * a) * c)))) / (2.0d0 * a)
end function
public static double code(double a, double b, double c) {
return (-b + Math.sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * a);
}
def code(a, b, c): return (-b + math.sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * a)
function code(a, b, c) return Float64(Float64(Float64(-b) + sqrt(Float64(Float64(b * b) - Float64(Float64(4.0 * a) * c)))) / Float64(2.0 * a)) end
function tmp = code(a, b, c) tmp = (-b + sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * a); end
code[a_, b_, c_] := N[(N[((-b) + N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(N[(4.0 * a), $MachinePrecision] * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(2.0 * a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a}
\end{array}
(FPCore (a b c) :precision binary64 (/ (* -2.0 c) (+ (sqrt (* (fma -4.0 c (/ (* b b) a)) a)) b)))
double code(double a, double b, double c) {
return (-2.0 * c) / (sqrt((fma(-4.0, c, ((b * b) / a)) * a)) + b);
}
function code(a, b, c) return Float64(Float64(-2.0 * c) / Float64(sqrt(Float64(fma(-4.0, c, Float64(Float64(b * b) / a)) * a)) + b)) end
code[a_, b_, c_] := N[(N[(-2.0 * c), $MachinePrecision] / N[(N[Sqrt[N[(N[(-4.0 * c + N[(N[(b * b), $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision] * a), $MachinePrecision]], $MachinePrecision] + b), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{-2 \cdot c}{\sqrt{\mathsf{fma}\left(-4, c, \frac{b \cdot b}{a}\right) \cdot a} + b}
\end{array}
Initial program 30.8%
lift-/.f64N/A
clear-numN/A
lift-*.f64N/A
associate-/l*N/A
associate-/r*N/A
metadata-evalN/A
lower-/.f64N/A
lower-/.f6430.8
lift-+.f64N/A
+-commutativeN/A
lift-neg.f64N/A
unsub-negN/A
lower--.f6430.8
Applied rewrites30.8%
lift-/.f64N/A
lift-/.f64N/A
associate-/r/N/A
lift--.f64N/A
flip--N/A
associate-*r/N/A
lower-/.f64N/A
Applied rewrites31.4%
Taylor expanded in a around 0
*-commutativeN/A
lower-*.f6499.7
Applied rewrites99.7%
Taylor expanded in a around inf
*-commutativeN/A
lower-*.f64N/A
lower-fma.f64N/A
lower-/.f64N/A
unpow2N/A
lower-*.f6499.7
Applied rewrites99.7%
Final simplification99.7%
(FPCore (a b c) :precision binary64 (/ (* -2.0 c) (+ (sqrt (fma b b (* (* -4.0 c) a))) b)))
double code(double a, double b, double c) {
return (-2.0 * c) / (sqrt(fma(b, b, ((-4.0 * c) * a))) + b);
}
function code(a, b, c) return Float64(Float64(-2.0 * c) / Float64(sqrt(fma(b, b, Float64(Float64(-4.0 * c) * a))) + b)) end
code[a_, b_, c_] := N[(N[(-2.0 * c), $MachinePrecision] / N[(N[Sqrt[N[(b * b + N[(N[(-4.0 * c), $MachinePrecision] * a), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] + b), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{-2 \cdot c}{\sqrt{\mathsf{fma}\left(b, b, \left(-4 \cdot c\right) \cdot a\right)} + b}
\end{array}
Initial program 31.1%
lift-/.f64N/A
clear-numN/A
lift-*.f64N/A
associate-/l*N/A
associate-/r*N/A
metadata-evalN/A
lower-/.f64N/A
lower-/.f6431.1
lift-+.f64N/A
+-commutativeN/A
lift-neg.f64N/A
unsub-negN/A
lower--.f6431.1
Applied rewrites31.1%
lift-/.f64N/A
lift-/.f64N/A
associate-/r/N/A
lift--.f64N/A
flip--N/A
associate-*r/N/A
lower-/.f64N/A
Applied rewrites32.0%
Taylor expanded in a around 0
*-commutativeN/A
lower-*.f6499.7
Applied rewrites99.7%
lift-fma.f64N/A
+-commutativeN/A
lift-*.f64N/A
lower-fma.f64N/A
lift-*.f64N/A
associate-*l*N/A
*-commutativeN/A
lower-*.f64N/A
*-commutativeN/A
lower-*.f6499.7
Applied rewrites99.7%
Final simplification99.7%
herbie shell --seed 2024234
(FPCore (a b c)
:name "Quadratic roots, medium range"
:precision binary64
:pre (and (and (and (< 1.1102230246251565e-16 a) (< a 9007199254740992.0)) (and (< 1.1102230246251565e-16 b) (< b 9007199254740992.0))) (and (< 1.1102230246251565e-16 c) (< c 9007199254740992.0)))
(/ (+ (- b) (sqrt (- (* b b) (* (* 4.0 a) c)))) (* 2.0 a)))