
(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 3 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) a (* b b))) b)))
double code(double a, double b, double c) {
return (-2.0 * c) / (sqrt(fma((-4.0 * c), a, (b * b))) + b);
}
function code(a, b, c) return Float64(Float64(-2.0 * c) / Float64(sqrt(fma(Float64(-4.0 * c), a, Float64(b * b))) + b)) end
code[a_, b_, c_] := N[(N[(-2.0 * c), $MachinePrecision] / N[(N[Sqrt[N[(N[(-4.0 * c), $MachinePrecision] * a + N[(b * b), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] + b), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{-2 \cdot c}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b}
\end{array}
Initial program 17.6%
lift--.f64N/A
sub-negN/A
lift-*.f64N/A
lower-fma.f64N/A
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
distribute-lft-neg-inN/A
*-commutativeN/A
associate-*r*N/A
lower-*.f64N/A
lower-*.f64N/A
metadata-eval17.7
Applied rewrites17.7%
lift-+.f64N/A
+-commutativeN/A
lift-fma.f64N/A
lift-*.f64N/A
+-commutativeN/A
lift-*.f64N/A
lift-fma.f64N/A
lift-neg.f64N/A
sub-negN/A
flip--N/A
lower-/.f64N/A
Applied rewrites18.1%
lift-/.f64N/A
lift-/.f64N/A
associate-/l/N/A
associate-/r*N/A
lower-/.f64N/A
lower-/.f6418.1
lift--.f64N/A
lift-fma.f64N/A
associate--l+N/A
+-inversesN/A
lower-fma.f6499.7
Applied rewrites99.7%
Taylor expanded in c around 0
*-commutativeN/A
lower-*.f6499.9
Applied rewrites99.9%
Final simplification99.9%
(FPCore (a b c) :precision binary64 (/ 0.5 (fma 0.5 (/ a b) (* -0.5 (/ b c)))))
double code(double a, double b, double c) {
return 0.5 / fma(0.5, (a / b), (-0.5 * (b / c)));
}
function code(a, b, c) return Float64(0.5 / fma(0.5, Float64(a / b), Float64(-0.5 * Float64(b / c)))) end
code[a_, b_, c_] := N[(0.5 / N[(0.5 * N[(a / b), $MachinePrecision] + N[(-0.5 * N[(b / c), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{0.5}{\mathsf{fma}\left(0.5, \frac{a}{b}, -0.5 \cdot \frac{b}{c}\right)}
\end{array}
Initial program 17.6%
lift-/.f64N/A
div-invN/A
lift-*.f64N/A
associate-/r*N/A
metadata-evalN/A
lift-+.f64N/A
flip-+N/A
clear-numN/A
frac-timesN/A
metadata-evalN/A
Applied rewrites17.6%
Taylor expanded in a around 0
+-commutativeN/A
lower-fma.f64N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f64N/A
lower-/.f6495.7
Applied rewrites95.7%
Final simplification95.7%
(FPCore (a b c) :precision binary64 (/ (- c) b))
double code(double a, double b, double c) {
return -c / 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 / b
end function
public static double code(double a, double b, double c) {
return -c / b;
}
def code(a, b, c): return -c / b
function code(a, b, c) return Float64(Float64(-c) / b) end
function tmp = code(a, b, c) tmp = -c / b; end
code[a_, b_, c_] := N[((-c) / b), $MachinePrecision]
\begin{array}{l}
\\
\frac{-c}{b}
\end{array}
Initial program 17.6%
Taylor expanded in c around 0
associate-*r/N/A
lower-/.f64N/A
mul-1-negN/A
lower-neg.f6490.5
Applied rewrites90.5%
herbie shell --seed 2024284
(FPCore (a b c)
:name "Quadratic roots, 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) (* (* 4.0 a) c)))) (* 2.0 a)))