
(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 10 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
(let* ((t_0 (* c (* c c))))
(fma
(fma
-2.0
(/ t_0 (* (* b b) (* b (* b b))))
(*
(/ (* (* c t_0) (* a 20.0)) (* b (* (* b b) (* (* b b) (* b b)))))
-0.25))
(* a a)
(/ (fma c (/ (* a c) (* b b)) c) (- b)))))
double code(double a, double b, double c) {
double t_0 = c * (c * c);
return fma(fma(-2.0, (t_0 / ((b * b) * (b * (b * b)))), ((((c * t_0) * (a * 20.0)) / (b * ((b * b) * ((b * b) * (b * b))))) * -0.25)), (a * a), (fma(c, ((a * c) / (b * b)), c) / -b));
}
function code(a, b, c) t_0 = Float64(c * Float64(c * c)) return fma(fma(-2.0, Float64(t_0 / Float64(Float64(b * b) * Float64(b * Float64(b * b)))), Float64(Float64(Float64(Float64(c * t_0) * Float64(a * 20.0)) / Float64(b * Float64(Float64(b * b) * Float64(Float64(b * b) * Float64(b * b))))) * -0.25)), Float64(a * a), Float64(fma(c, Float64(Float64(a * c) / Float64(b * b)), c) / Float64(-b))) end
code[a_, b_, c_] := Block[{t$95$0 = N[(c * N[(c * c), $MachinePrecision]), $MachinePrecision]}, N[(N[(-2.0 * N[(t$95$0 / N[(N[(b * b), $MachinePrecision] * N[(b * N[(b * b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(N[(N[(N[(c * t$95$0), $MachinePrecision] * N[(a * 20.0), $MachinePrecision]), $MachinePrecision] / N[(b * N[(N[(b * b), $MachinePrecision] * N[(N[(b * b), $MachinePrecision] * N[(b * b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] * -0.25), $MachinePrecision]), $MachinePrecision] * N[(a * a), $MachinePrecision] + N[(N[(c * N[(N[(a * c), $MachinePrecision] / N[(b * b), $MachinePrecision]), $MachinePrecision] + c), $MachinePrecision] / (-b)), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := c \cdot \left(c \cdot c\right)\\
\mathsf{fma}\left(\mathsf{fma}\left(-2, \frac{t\_0}{\left(b \cdot b\right) \cdot \left(b \cdot \left(b \cdot b\right)\right)}, \frac{\left(c \cdot t\_0\right) \cdot \left(a \cdot 20\right)}{b \cdot \left(\left(b \cdot b\right) \cdot \left(\left(b \cdot b\right) \cdot \left(b \cdot b\right)\right)\right)} \cdot -0.25\right), a \cdot a, \frac{\mathsf{fma}\left(c, \frac{a \cdot c}{b \cdot b}, c\right)}{-b}\right)
\end{array}
\end{array}
Initial program 31.3%
Taylor expanded in a around 0
Applied rewrites94.8%
Applied rewrites94.8%
Final simplification94.8%
(FPCore (a b c)
:precision binary64
(let* ((t_0 (fma c (* a -4.0) (* b b))))
(if (<= (/ (- (sqrt (- (* b b) (* c (* 4.0 a)))) b) (* a 2.0)) -1000.0)
(/ (/ 1.0 (/ (+ b (sqrt t_0)) (- t_0 (* b b)))) (* a 2.0))
(/ (fma (* c c) (/ a (* b b)) c) (- b)))))
double code(double a, double b, double c) {
double t_0 = fma(c, (a * -4.0), (b * b));
double tmp;
if (((sqrt(((b * b) - (c * (4.0 * a)))) - b) / (a * 2.0)) <= -1000.0) {
tmp = (1.0 / ((b + sqrt(t_0)) / (t_0 - (b * b)))) / (a * 2.0);
} else {
tmp = fma((c * c), (a / (b * b)), c) / -b;
}
return tmp;
}
function code(a, b, c) t_0 = fma(c, Float64(a * -4.0), Float64(b * b)) tmp = 0.0 if (Float64(Float64(sqrt(Float64(Float64(b * b) - Float64(c * Float64(4.0 * a)))) - b) / Float64(a * 2.0)) <= -1000.0) tmp = Float64(Float64(1.0 / Float64(Float64(b + sqrt(t_0)) / Float64(t_0 - Float64(b * b)))) / Float64(a * 2.0)); else tmp = Float64(fma(Float64(c * c), Float64(a / Float64(b * b)), c) / Float64(-b)); end return tmp end
code[a_, b_, c_] := Block[{t$95$0 = N[(c * N[(a * -4.0), $MachinePrecision] + N[(b * b), $MachinePrecision]), $MachinePrecision]}, If[LessEqual[N[(N[(N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(c * N[(4.0 * a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] - b), $MachinePrecision] / N[(a * 2.0), $MachinePrecision]), $MachinePrecision], -1000.0], N[(N[(1.0 / N[(N[(b + N[Sqrt[t$95$0], $MachinePrecision]), $MachinePrecision] / N[(t$95$0 - N[(b * b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(a * 2.0), $MachinePrecision]), $MachinePrecision], N[(N[(N[(c * c), $MachinePrecision] * N[(a / N[(b * b), $MachinePrecision]), $MachinePrecision] + c), $MachinePrecision] / (-b)), $MachinePrecision]]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \mathsf{fma}\left(c, a \cdot -4, b \cdot b\right)\\
\mathbf{if}\;\frac{\sqrt{b \cdot b - c \cdot \left(4 \cdot a\right)} - b}{a \cdot 2} \leq -1000:\\
\;\;\;\;\frac{\frac{1}{\frac{b + \sqrt{t\_0}}{t\_0 - b \cdot b}}}{a \cdot 2}\\
\mathbf{else}:\\
\;\;\;\;\frac{\mathsf{fma}\left(c \cdot c, \frac{a}{b \cdot b}, c\right)}{-b}\\
\end{array}
\end{array}
if (/.f64 (+.f64 (neg.f64 b) (sqrt.f64 (-.f64 (*.f64 b b) (*.f64 (*.f64 #s(literal 4 binary64) a) c)))) (*.f64 #s(literal 2 binary64) a)) < -1e3Initial program 72.3%
lift-+.f64N/A
+-commutativeN/A
lift-neg.f64N/A
unsub-negN/A
lower--.f6472.3
lift--.f64N/A
sub-negN/A
+-commutativeN/A
lift-*.f64N/A
distribute-lft-neg-inN/A
lift-*.f64N/A
*-commutativeN/A
distribute-rgt-neg-inN/A
associate-*l*N/A
lower-fma.f64N/A
lower-*.f64N/A
metadata-eval72.3
Applied rewrites72.3%
lift--.f64N/A
flip--N/A
clear-numN/A
lower-/.f64N/A
lower-/.f64N/A
Applied rewrites73.7%
if -1e3 < (/.f64 (+.f64 (neg.f64 b) (sqrt.f64 (-.f64 (*.f64 b b) (*.f64 (*.f64 #s(literal 4 binary64) a) c)))) (*.f64 #s(literal 2 binary64) a)) Initial program 27.9%
Taylor expanded in b around inf
distribute-lft-outN/A
associate-/l*N/A
mul-1-negN/A
lower-neg.f64N/A
lower-/.f64N/A
+-commutativeN/A
*-commutativeN/A
associate-/l*N/A
lower-fma.f64N/A
unpow2N/A
lower-*.f64N/A
lower-/.f64N/A
unpow2N/A
lower-*.f6492.8
Applied rewrites92.8%
Final simplification91.2%
herbie shell --seed 2024222
(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)))