
(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 9 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
(if (<= b -1.95e+101)
(- (/ b a))
(if (<= b 1.12e-51)
(fma (/ (sqrt (fma a (* c -4.0) (* b b))) a) 0.5 (/ b (* a -2.0)))
(/ c (- b)))))
double code(double a, double b, double c) {
double tmp;
if (b <= -1.95e+101) {
tmp = -(b / a);
} else if (b <= 1.12e-51) {
tmp = fma((sqrt(fma(a, (c * -4.0), (b * b))) / a), 0.5, (b / (a * -2.0)));
} else {
tmp = c / -b;
}
return tmp;
}
function code(a, b, c) tmp = 0.0 if (b <= -1.95e+101) tmp = Float64(-Float64(b / a)); elseif (b <= 1.12e-51) tmp = fma(Float64(sqrt(fma(a, Float64(c * -4.0), Float64(b * b))) / a), 0.5, Float64(b / Float64(a * -2.0))); else tmp = Float64(c / Float64(-b)); end return tmp end
code[a_, b_, c_] := If[LessEqual[b, -1.95e+101], (-N[(b / a), $MachinePrecision]), If[LessEqual[b, 1.12e-51], N[(N[(N[Sqrt[N[(a * N[(c * -4.0), $MachinePrecision] + N[(b * b), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] / a), $MachinePrecision] * 0.5 + N[(b / N[(a * -2.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(c / (-b)), $MachinePrecision]]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;b \leq -1.95 \cdot 10^{+101}:\\
\;\;\;\;-\frac{b}{a}\\
\mathbf{elif}\;b \leq 1.12 \cdot 10^{-51}:\\
\;\;\;\;\mathsf{fma}\left(\frac{\sqrt{\mathsf{fma}\left(a, c \cdot -4, b \cdot b\right)}}{a}, 0.5, \frac{b}{a \cdot -2}\right)\\
\mathbf{else}:\\
\;\;\;\;\frac{c}{-b}\\
\end{array}
\end{array}
if b < -1.95e101Initial program 62.9%
Taylor expanded in b around -inf
mul-1-negN/A
distribute-neg-frac2N/A
mul-1-negN/A
lower-/.f64N/A
mul-1-negN/A
lower-neg.f6498.2
Applied rewrites98.2%
if -1.95e101 < b < 1.11999999999999998e-51Initial program 76.5%
lift-+.f64N/A
+-commutativeN/A
lift-neg.f64N/A
unsub-negN/A
lower--.f6476.5
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-eval76.5
Applied rewrites76.5%
lift-/.f64N/A
lift--.f64N/A
div-subN/A
sub-negN/A
lift-*.f64N/A
*-commutativeN/A
associate-/r*N/A
div-invN/A
metadata-evalN/A
lower-fma.f64N/A
lower-/.f64N/A
lower-neg.f64N/A
lower-/.f6476.5
lift-*.f64N/A
*-commutativeN/A
lower-*.f6476.5
Applied rewrites76.5%
lift-neg.f64N/A
lift-/.f64N/A
distribute-neg-frac2N/A
lift-*.f64N/A
*-commutativeN/A
lower-/.f64N/A
*-commutativeN/A
distribute-rgt-neg-inN/A
lower-*.f64N/A
metadata-eval76.5
Applied rewrites76.5%
if 1.11999999999999998e-51 < b Initial program 23.4%
Taylor expanded in b around inf
mul-1-negN/A
distribute-neg-frac2N/A
lower-/.f64N/A
lower-neg.f6482.7
Applied rewrites82.7%
Final simplification83.5%
(FPCore (a b c)
:precision binary64
(if (<= b -1.95e+101)
(- (/ b a))
(if (<= b 1.12e-51)
(/ (- (sqrt (- (* b b) (* c (* 4.0 a)))) b) (* a 2.0))
(/ c (- b)))))
double code(double a, double b, double c) {
double tmp;
if (b <= -1.95e+101) {
tmp = -(b / a);
} else if (b <= 1.12e-51) {
tmp = (sqrt(((b * b) - (c * (4.0 * a)))) - b) / (a * 2.0);
} else {
tmp = c / -b;
}
return tmp;
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
real(8) :: tmp
if (b <= (-1.95d+101)) then
tmp = -(b / a)
else if (b <= 1.12d-51) then
tmp = (sqrt(((b * b) - (c * (4.0d0 * a)))) - b) / (a * 2.0d0)
else
tmp = c / -b
end if
code = tmp
end function
public static double code(double a, double b, double c) {
double tmp;
if (b <= -1.95e+101) {
tmp = -(b / a);
} else if (b <= 1.12e-51) {
tmp = (Math.sqrt(((b * b) - (c * (4.0 * a)))) - b) / (a * 2.0);
} else {
tmp = c / -b;
}
return tmp;
}
def code(a, b, c): tmp = 0 if b <= -1.95e+101: tmp = -(b / a) elif b <= 1.12e-51: tmp = (math.sqrt(((b * b) - (c * (4.0 * a)))) - b) / (a * 2.0) else: tmp = c / -b return tmp
function code(a, b, c) tmp = 0.0 if (b <= -1.95e+101) tmp = Float64(-Float64(b / a)); elseif (b <= 1.12e-51) tmp = Float64(Float64(sqrt(Float64(Float64(b * b) - Float64(c * Float64(4.0 * a)))) - b) / Float64(a * 2.0)); else tmp = Float64(c / Float64(-b)); end return tmp end
function tmp_2 = code(a, b, c) tmp = 0.0; if (b <= -1.95e+101) tmp = -(b / a); elseif (b <= 1.12e-51) tmp = (sqrt(((b * b) - (c * (4.0 * a)))) - b) / (a * 2.0); else tmp = c / -b; end tmp_2 = tmp; end
code[a_, b_, c_] := If[LessEqual[b, -1.95e+101], (-N[(b / a), $MachinePrecision]), If[LessEqual[b, 1.12e-51], 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], N[(c / (-b)), $MachinePrecision]]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;b \leq -1.95 \cdot 10^{+101}:\\
\;\;\;\;-\frac{b}{a}\\
\mathbf{elif}\;b \leq 1.12 \cdot 10^{-51}:\\
\;\;\;\;\frac{\sqrt{b \cdot b - c \cdot \left(4 \cdot a\right)} - b}{a \cdot 2}\\
\mathbf{else}:\\
\;\;\;\;\frac{c}{-b}\\
\end{array}
\end{array}
if b < -1.95e101Initial program 53.7%
Taylor expanded in b around -inf
mul-1-negN/A
distribute-neg-frac2N/A
mul-1-negN/A
lower-/.f64N/A
mul-1-negN/A
lower-neg.f6495.7
Applied rewrites95.7%
if -1.95e101 < b < 1.11999999999999998e-51Initial program 79.9%
if 1.11999999999999998e-51 < b Initial program 16.4%
Taylor expanded in b around inf
mul-1-negN/A
distribute-neg-frac2N/A
lower-/.f64N/A
lower-neg.f6487.3
Applied rewrites87.3%
Final simplification85.8%
herbie shell --seed 2024226
(FPCore (a b c)
:name "Quadratic roots, full range"
:precision binary64
(/ (+ (- b) (sqrt (- (* b b) (* (* 4.0 a) c)))) (* 2.0 a)))