
(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(4.0 * Float64(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[(4.0 * N[(a * c), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(2.0 * a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\left(-b\right) - \sqrt{b \cdot b - 4 \cdot \left(a \cdot c\right)}}{2 \cdot a}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 12 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(4.0 * Float64(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[(4.0 * N[(a * c), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(2.0 * a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\left(-b\right) - \sqrt{b \cdot b - 4 \cdot \left(a \cdot c\right)}}{2 \cdot a}
\end{array}
(FPCore (a b c)
:precision binary64
(if (<= b -1e+104)
(- (/ c b))
(if (<= b -7e-275)
(/ c (* (- b (sqrt (fma -4.0 (* c a) (* b b)))) -0.5))
(if (<= b 1.8e+127)
(/ (+ b (sqrt (fma b b (* c (* -4.0 a))))) (* a -2.0))
(- (/ b a))))))
double code(double a, double b, double c) {
double tmp;
if (b <= -1e+104) {
tmp = -(c / b);
} else if (b <= -7e-275) {
tmp = c / ((b - sqrt(fma(-4.0, (c * a), (b * b)))) * -0.5);
} else if (b <= 1.8e+127) {
tmp = (b + sqrt(fma(b, b, (c * (-4.0 * a))))) / (a * -2.0);
} else {
tmp = -(b / a);
}
return tmp;
}
function code(a, b, c) tmp = 0.0 if (b <= -1e+104) tmp = Float64(-Float64(c / b)); elseif (b <= -7e-275) tmp = Float64(c / Float64(Float64(b - sqrt(fma(-4.0, Float64(c * a), Float64(b * b)))) * -0.5)); elseif (b <= 1.8e+127) tmp = Float64(Float64(b + sqrt(fma(b, b, Float64(c * Float64(-4.0 * a))))) / Float64(a * -2.0)); else tmp = Float64(-Float64(b / a)); end return tmp end
code[a_, b_, c_] := If[LessEqual[b, -1e+104], (-N[(c / b), $MachinePrecision]), If[LessEqual[b, -7e-275], N[(c / N[(N[(b - N[Sqrt[N[(-4.0 * N[(c * a), $MachinePrecision] + N[(b * b), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * -0.5), $MachinePrecision]), $MachinePrecision], If[LessEqual[b, 1.8e+127], N[(N[(b + N[Sqrt[N[(b * b + N[(c * N[(-4.0 * a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(a * -2.0), $MachinePrecision]), $MachinePrecision], (-N[(b / a), $MachinePrecision])]]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;b \leq -1 \cdot 10^{+104}:\\
\;\;\;\;-\frac{c}{b}\\
\mathbf{elif}\;b \leq -7 \cdot 10^{-275}:\\
\;\;\;\;\frac{c}{\left(b - \sqrt{\mathsf{fma}\left(-4, c \cdot a, b \cdot b\right)}\right) \cdot -0.5}\\
\mathbf{elif}\;b \leq 1.8 \cdot 10^{+127}:\\
\;\;\;\;\frac{b + \sqrt{\mathsf{fma}\left(b, b, c \cdot \left(-4 \cdot a\right)\right)}}{a \cdot -2}\\
\mathbf{else}:\\
\;\;\;\;-\frac{b}{a}\\
\end{array}
\end{array}
if b < -1e104Initial program 4.6%
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.f6489.0
Simplified89.0%
if -1e104 < b < -6.99999999999999938e-275Initial program 53.5%
Applied egg-rr53.6%
Applied egg-rr67.5%
lift-*.f64N/A
lift-*.f64N/A
lift-*.f64N/A
lift-fma.f64N/A
lift-sqrt.f64N/A
lift--.f64N/A
lift-*.f64N/A
lift-*.f64N/A
associate-/l*N/A
lift-*.f64N/A
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
Applied egg-rr89.1%
lift-*.f64N/A
lift-*.f64N/A
lift-fma.f64N/A
lift-sqrt.f64N/A
lift--.f64N/A
lift-*.f64N/A
clear-numN/A
un-div-invN/A
lower-/.f64N/A
Applied egg-rr89.3%
if -6.99999999999999938e-275 < b < 1.79999999999999989e127Initial program 87.1%
Applied egg-rr87.2%
if 1.79999999999999989e127 < b Initial program 51.6%
Taylor expanded in b around inf
mul-1-negN/A
lower-neg.f64N/A
lower-/.f64100.0
Simplified100.0%
Final simplification90.9%
(FPCore (a b c)
:precision binary64
(if (<= b -1e+104)
(- (/ c b))
(if (<= b -7e-234)
(/ c (* (- b (sqrt (fma -4.0 (* c a) (* b b)))) -0.5))
(if (<= b 1.7e+127)
(* (+ b (sqrt (fma b b (* c (* -4.0 a))))) (/ -0.5 a))
(- (/ b a))))))
double code(double a, double b, double c) {
double tmp;
if (b <= -1e+104) {
tmp = -(c / b);
} else if (b <= -7e-234) {
tmp = c / ((b - sqrt(fma(-4.0, (c * a), (b * b)))) * -0.5);
} else if (b <= 1.7e+127) {
tmp = (b + sqrt(fma(b, b, (c * (-4.0 * a))))) * (-0.5 / a);
} else {
tmp = -(b / a);
}
return tmp;
}
function code(a, b, c) tmp = 0.0 if (b <= -1e+104) tmp = Float64(-Float64(c / b)); elseif (b <= -7e-234) tmp = Float64(c / Float64(Float64(b - sqrt(fma(-4.0, Float64(c * a), Float64(b * b)))) * -0.5)); elseif (b <= 1.7e+127) tmp = Float64(Float64(b + sqrt(fma(b, b, Float64(c * Float64(-4.0 * a))))) * Float64(-0.5 / a)); else tmp = Float64(-Float64(b / a)); end return tmp end
code[a_, b_, c_] := If[LessEqual[b, -1e+104], (-N[(c / b), $MachinePrecision]), If[LessEqual[b, -7e-234], N[(c / N[(N[(b - N[Sqrt[N[(-4.0 * N[(c * a), $MachinePrecision] + N[(b * b), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * -0.5), $MachinePrecision]), $MachinePrecision], If[LessEqual[b, 1.7e+127], N[(N[(b + N[Sqrt[N[(b * b + N[(c * N[(-4.0 * a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * N[(-0.5 / a), $MachinePrecision]), $MachinePrecision], (-N[(b / a), $MachinePrecision])]]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;b \leq -1 \cdot 10^{+104}:\\
\;\;\;\;-\frac{c}{b}\\
\mathbf{elif}\;b \leq -7 \cdot 10^{-234}:\\
\;\;\;\;\frac{c}{\left(b - \sqrt{\mathsf{fma}\left(-4, c \cdot a, b \cdot b\right)}\right) \cdot -0.5}\\
\mathbf{elif}\;b \leq 1.7 \cdot 10^{+127}:\\
\;\;\;\;\left(b + \sqrt{\mathsf{fma}\left(b, b, c \cdot \left(-4 \cdot a\right)\right)}\right) \cdot \frac{-0.5}{a}\\
\mathbf{else}:\\
\;\;\;\;-\frac{b}{a}\\
\end{array}
\end{array}
if b < -1e104Initial program 7.3%
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.f6496.2
Simplified96.2%
if -1e104 < b < -7.0000000000000003e-234Initial program 46.6%
Applied egg-rr46.5%
Applied egg-rr68.9%
lift-*.f64N/A
lift-*.f64N/A
lift-*.f64N/A
lift-fma.f64N/A
lift-sqrt.f64N/A
lift--.f64N/A
lift-*.f64N/A
lift-*.f64N/A
associate-/l*N/A
lift-*.f64N/A
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
Applied egg-rr88.3%
lift-*.f64N/A
lift-*.f64N/A
lift-fma.f64N/A
lift-sqrt.f64N/A
lift--.f64N/A
lift-*.f64N/A
clear-numN/A
un-div-invN/A
lower-/.f64N/A
Applied egg-rr88.6%
if -7.0000000000000003e-234 < b < 1.69999999999999989e127Initial program 86.1%
Applied egg-rr85.8%
if 1.69999999999999989e127 < b Initial program 48.5%
Taylor expanded in b around inf
mul-1-negN/A
lower-neg.f64N/A
lower-/.f6496.9
Simplified96.9%
Final simplification90.8%
(FPCore (a b c)
:precision binary64
(let* ((t_0 (sqrt (- (* b b) (* 4.0 (* a c))))))
(if (< b 0.0)
(/ c (* a (/ (+ (- b) t_0) (* 2.0 a))))
(/ (- (- b) t_0) (* 2.0 a)))))
double code(double a, double b, double c) {
double t_0 = sqrt(((b * b) - (4.0 * (a * c))));
double tmp;
if (b < 0.0) {
tmp = c / (a * ((-b + t_0) / (2.0 * a)));
} else {
tmp = (-b - t_0) / (2.0 * a);
}
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) :: t_0
real(8) :: tmp
t_0 = sqrt(((b * b) - (4.0d0 * (a * c))))
if (b < 0.0d0) then
tmp = c / (a * ((-b + t_0) / (2.0d0 * a)))
else
tmp = (-b - t_0) / (2.0d0 * a)
end if
code = tmp
end function
public static double code(double a, double b, double c) {
double t_0 = Math.sqrt(((b * b) - (4.0 * (a * c))));
double tmp;
if (b < 0.0) {
tmp = c / (a * ((-b + t_0) / (2.0 * a)));
} else {
tmp = (-b - t_0) / (2.0 * a);
}
return tmp;
}
def code(a, b, c): t_0 = math.sqrt(((b * b) - (4.0 * (a * c)))) tmp = 0 if b < 0.0: tmp = c / (a * ((-b + t_0) / (2.0 * a))) else: tmp = (-b - t_0) / (2.0 * a) return tmp
function code(a, b, c) t_0 = sqrt(Float64(Float64(b * b) - Float64(4.0 * Float64(a * c)))) tmp = 0.0 if (b < 0.0) tmp = Float64(c / Float64(a * Float64(Float64(Float64(-b) + t_0) / Float64(2.0 * a)))); else tmp = Float64(Float64(Float64(-b) - t_0) / Float64(2.0 * a)); end return tmp end
function tmp_2 = code(a, b, c) t_0 = sqrt(((b * b) - (4.0 * (a * c)))); tmp = 0.0; if (b < 0.0) tmp = c / (a * ((-b + t_0) / (2.0 * a))); else tmp = (-b - t_0) / (2.0 * a); end tmp_2 = tmp; end
code[a_, b_, c_] := Block[{t$95$0 = N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(4.0 * N[(a * c), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]}, If[Less[b, 0.0], N[(c / N[(a * N[(N[((-b) + t$95$0), $MachinePrecision] / N[(2.0 * a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(N[((-b) - t$95$0), $MachinePrecision] / N[(2.0 * a), $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{b \cdot b - 4 \cdot \left(a \cdot c\right)}\\
\mathbf{if}\;b < 0:\\
\;\;\;\;\frac{c}{a \cdot \frac{\left(-b\right) + t\_0}{2 \cdot a}}\\
\mathbf{else}:\\
\;\;\;\;\frac{\left(-b\right) - t\_0}{2 \cdot a}\\
\end{array}
\end{array}
herbie shell --seed 2024218
(FPCore (a b c)
:name "The quadratic formula (r2)"
:precision binary64
:alt
(! :herbie-platform default (let ((d (sqrt (- (* b b) (* 4 (* a c)))))) (let ((r1 (/ (+ (- b) d) (* 2 a)))) (let ((r2 (/ (- (- b) d) (* 2 a)))) (if (< b 0) (/ c (* a r1)) r2)))))
(/ (- (- b) (sqrt (- (* b b) (* 4.0 (* a c))))) (* 2.0 a)))