
(FPCore (a b c) :precision binary64 (/ (+ (- b) (sqrt (- (* b b) (* (* 3.0 a) c)))) (* 3.0 a)))
double code(double a, double b, double c) {
return (-b + sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * 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) - ((3.0d0 * a) * c)))) / (3.0d0 * a)
end function
public static double code(double a, double b, double c) {
return (-b + Math.sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a);
}
def code(a, b, c): return (-b + math.sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a)
function code(a, b, c) return Float64(Float64(Float64(-b) + sqrt(Float64(Float64(b * b) - Float64(Float64(3.0 * a) * c)))) / Float64(3.0 * a)) end
function tmp = code(a, b, c) tmp = (-b + sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a); end
code[a_, b_, c_] := N[(N[((-b) + N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(N[(3.0 * a), $MachinePrecision] * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(3.0 * a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 6 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (a b c) :precision binary64 (/ (+ (- b) (sqrt (- (* b b) (* (* 3.0 a) c)))) (* 3.0 a)))
double code(double a, double b, double c) {
return (-b + sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * 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) - ((3.0d0 * a) * c)))) / (3.0d0 * a)
end function
public static double code(double a, double b, double c) {
return (-b + Math.sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a);
}
def code(a, b, c): return (-b + math.sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a)
function code(a, b, c) return Float64(Float64(Float64(-b) + sqrt(Float64(Float64(b * b) - Float64(Float64(3.0 * a) * c)))) / Float64(3.0 * a)) end
function tmp = code(a, b, c) tmp = (-b + sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a); end
code[a_, b_, c_] := N[(N[((-b) + N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(N[(3.0 * a), $MachinePrecision] * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(3.0 * a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}
\end{array}
(FPCore (a b c) :precision binary64 (/ (- (* (* c a) 3.0)) (* (+ b (sqrt (* (fma -3.0 c (/ (* b b) a)) a))) (* a 3.0))))
double code(double a, double b, double c) {
return -((c * a) * 3.0) / ((b + sqrt((fma(-3.0, c, ((b * b) / a)) * a))) * (a * 3.0));
}
function code(a, b, c) return Float64(Float64(-Float64(Float64(c * a) * 3.0)) / Float64(Float64(b + sqrt(Float64(fma(-3.0, c, Float64(Float64(b * b) / a)) * a))) * Float64(a * 3.0))) end
code[a_, b_, c_] := N[((-N[(N[(c * a), $MachinePrecision] * 3.0), $MachinePrecision]) / N[(N[(b + N[Sqrt[N[(N[(-3.0 * c + N[(N[(b * b), $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision] * a), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * N[(a * 3.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{-\left(c \cdot a\right) \cdot 3}{\left(b + \sqrt{\mathsf{fma}\left(-3, c, \frac{b \cdot b}{a}\right) \cdot a}\right) \cdot \left(a \cdot 3\right)}
\end{array}
Initial program 34.9%
Taylor expanded in a around inf
*-commutativeN/A
lower-*.f64N/A
fp-cancel-sub-sign-invN/A
metadata-evalN/A
+-commutativeN/A
lower-fma.f64N/A
lower-/.f64N/A
unpow2N/A
lower-*.f6434.8
Applied rewrites34.8%
lift-/.f64N/A
lift-+.f64N/A
flip-+N/A
associate-/l/N/A
lower-/.f64N/A
Applied rewrites35.5%
Taylor expanded in a around 0
*-commutativeN/A
lower-*.f64N/A
*-commutativeN/A
lower-*.f6499.2
Applied rewrites99.2%
Final simplification99.2%
(FPCore (a b c) :precision binary64 (if (<= (/ (+ (- b) (sqrt (- (* b b) (* (* 3.0 a) c)))) (* 3.0 a)) -9e-8) (/ (+ (- b) (sqrt (fma (* c a) -3.0 (* b b)))) (* 3.0 a)) (* (/ c b) -0.5)))
double code(double a, double b, double c) {
double tmp;
if (((-b + sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a)) <= -9e-8) {
tmp = (-b + sqrt(fma((c * a), -3.0, (b * b)))) / (3.0 * a);
} else {
tmp = (c / b) * -0.5;
}
return tmp;
}
function code(a, b, c) tmp = 0.0 if (Float64(Float64(Float64(-b) + sqrt(Float64(Float64(b * b) - Float64(Float64(3.0 * a) * c)))) / Float64(3.0 * a)) <= -9e-8) tmp = Float64(Float64(Float64(-b) + sqrt(fma(Float64(c * a), -3.0, Float64(b * b)))) / Float64(3.0 * a)); else tmp = Float64(Float64(c / b) * -0.5); end return tmp end
code[a_, b_, c_] := If[LessEqual[N[(N[((-b) + N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(N[(3.0 * a), $MachinePrecision] * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(3.0 * a), $MachinePrecision]), $MachinePrecision], -9e-8], N[(N[((-b) + N[Sqrt[N[(N[(c * a), $MachinePrecision] * -3.0 + N[(b * b), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(3.0 * a), $MachinePrecision]), $MachinePrecision], N[(N[(c / b), $MachinePrecision] * -0.5), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \leq -9 \cdot 10^{-8}:\\
\;\;\;\;\frac{\left(-b\right) + \sqrt{\mathsf{fma}\left(c \cdot a, -3, b \cdot b\right)}}{3 \cdot a}\\
\mathbf{else}:\\
\;\;\;\;\frac{c}{b} \cdot -0.5\\
\end{array}
\end{array}
if (/.f64 (+.f64 (neg.f64 b) (sqrt.f64 (-.f64 (*.f64 b b) (*.f64 (*.f64 #s(literal 3 binary64) a) c)))) (*.f64 #s(literal 3 binary64) a)) < -8.99999999999999986e-8Initial program 67.2%
lift--.f64N/A
lift-*.f64N/A
fp-cancel-sub-sign-invN/A
+-commutativeN/A
lift-*.f64N/A
distribute-lft-neg-inN/A
associate-*r*N/A
*-commutativeN/A
lower-fma.f64N/A
*-commutativeN/A
lower-*.f64N/A
metadata-eval67.3
Applied rewrites67.3%
if -8.99999999999999986e-8 < (/.f64 (+.f64 (neg.f64 b) (sqrt.f64 (-.f64 (*.f64 b b) (*.f64 (*.f64 #s(literal 3 binary64) a) c)))) (*.f64 #s(literal 3 binary64) a)) Initial program 17.7%
Taylor expanded in a around 0
*-commutativeN/A
lower-*.f64N/A
lower-/.f6491.1
Applied rewrites91.1%
(FPCore (a b c) :precision binary64 (if (<= (/ (+ (- b) (sqrt (- (* b b) (* (* 3.0 a) c)))) (* 3.0 a)) -9e-8) (/ (+ (- b) (sqrt (fma b b (* (* -3.0 a) c)))) (* 3.0 a)) (* (/ c b) -0.5)))
double code(double a, double b, double c) {
double tmp;
if (((-b + sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a)) <= -9e-8) {
tmp = (-b + sqrt(fma(b, b, ((-3.0 * a) * c)))) / (3.0 * a);
} else {
tmp = (c / b) * -0.5;
}
return tmp;
}
function code(a, b, c) tmp = 0.0 if (Float64(Float64(Float64(-b) + sqrt(Float64(Float64(b * b) - Float64(Float64(3.0 * a) * c)))) / Float64(3.0 * a)) <= -9e-8) tmp = Float64(Float64(Float64(-b) + sqrt(fma(b, b, Float64(Float64(-3.0 * a) * c)))) / Float64(3.0 * a)); else tmp = Float64(Float64(c / b) * -0.5); end return tmp end
code[a_, b_, c_] := If[LessEqual[N[(N[((-b) + N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(N[(3.0 * a), $MachinePrecision] * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(3.0 * a), $MachinePrecision]), $MachinePrecision], -9e-8], N[(N[((-b) + N[Sqrt[N[(b * b + N[(N[(-3.0 * a), $MachinePrecision] * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(3.0 * a), $MachinePrecision]), $MachinePrecision], N[(N[(c / b), $MachinePrecision] * -0.5), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \leq -9 \cdot 10^{-8}:\\
\;\;\;\;\frac{\left(-b\right) + \sqrt{\mathsf{fma}\left(b, b, \left(-3 \cdot a\right) \cdot c\right)}}{3 \cdot a}\\
\mathbf{else}:\\
\;\;\;\;\frac{c}{b} \cdot -0.5\\
\end{array}
\end{array}
if (/.f64 (+.f64 (neg.f64 b) (sqrt.f64 (-.f64 (*.f64 b b) (*.f64 (*.f64 #s(literal 3 binary64) a) c)))) (*.f64 #s(literal 3 binary64) a)) < -8.99999999999999986e-8Initial program 67.2%
lift--.f64N/A
lift-*.f64N/A
fp-cancel-sub-sign-invN/A
lift-*.f64N/A
lower-fma.f64N/A
lower-*.f64N/A
lift-*.f64N/A
distribute-lft-neg-inN/A
lower-*.f64N/A
metadata-eval67.2
Applied rewrites67.2%
if -8.99999999999999986e-8 < (/.f64 (+.f64 (neg.f64 b) (sqrt.f64 (-.f64 (*.f64 b b) (*.f64 (*.f64 #s(literal 3 binary64) a) c)))) (*.f64 #s(literal 3 binary64) a)) Initial program 17.7%
Taylor expanded in a around 0
*-commutativeN/A
lower-*.f64N/A
lower-/.f6491.1
Applied rewrites91.1%
(FPCore (a b c) :precision binary64 (/ (fma (/ (* -0.375 a) b) (/ (* c c) b) (* -0.5 c)) b))
double code(double a, double b, double c) {
return fma(((-0.375 * a) / b), ((c * c) / b), (-0.5 * c)) / b;
}
function code(a, b, c) return Float64(fma(Float64(Float64(-0.375 * a) / b), Float64(Float64(c * c) / b), Float64(-0.5 * c)) / b) end
code[a_, b_, c_] := N[(N[(N[(N[(-0.375 * a), $MachinePrecision] / b), $MachinePrecision] * N[(N[(c * c), $MachinePrecision] / b), $MachinePrecision] + N[(-0.5 * c), $MachinePrecision]), $MachinePrecision] / b), $MachinePrecision]
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\frac{-0.375 \cdot a}{b}, \frac{c \cdot c}{b}, -0.5 \cdot c\right)}{b}
\end{array}
Initial program 34.9%
Taylor expanded in a around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
Applied rewrites95.3%
Taylor expanded in b around inf
lower-/.f64N/A
+-commutativeN/A
associate-*r/N/A
associate-*r*N/A
unpow2N/A
times-fracN/A
lower-fma.f64N/A
lower-/.f64N/A
lower-*.f64N/A
lower-/.f64N/A
unpow2N/A
lower-*.f64N/A
lower-*.f6489.5
Applied rewrites89.5%
(FPCore (a b c) :precision binary64 (* (/ c b) -0.5))
double code(double a, double b, double c) {
return (c / b) * -0.5;
}
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) * (-0.5d0)
end function
public static double code(double a, double b, double c) {
return (c / b) * -0.5;
}
def code(a, b, c): return (c / b) * -0.5
function code(a, b, c) return Float64(Float64(c / b) * -0.5) end
function tmp = code(a, b, c) tmp = (c / b) * -0.5; end
code[a_, b_, c_] := N[(N[(c / b), $MachinePrecision] * -0.5), $MachinePrecision]
\begin{array}{l}
\\
\frac{c}{b} \cdot -0.5
\end{array}
Initial program 34.9%
Taylor expanded in a around 0
*-commutativeN/A
lower-*.f64N/A
lower-/.f6478.8
Applied rewrites78.8%
(FPCore (a b c) :precision binary64 (* c (/ -0.5 b)))
double code(double a, double b, double c) {
return c * (-0.5 / 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 * ((-0.5d0) / b)
end function
public static double code(double a, double b, double c) {
return c * (-0.5 / b);
}
def code(a, b, c): return c * (-0.5 / b)
function code(a, b, c) return Float64(c * Float64(-0.5 / b)) end
function tmp = code(a, b, c) tmp = c * (-0.5 / b); end
code[a_, b_, c_] := N[(c * N[(-0.5 / b), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
c \cdot \frac{-0.5}{b}
\end{array}
Initial program 34.9%
Taylor expanded in a around 0
*-commutativeN/A
lower-*.f64N/A
lower-/.f6478.8
Applied rewrites78.8%
Applied rewrites78.6%
herbie shell --seed 2024337
(FPCore (a b c)
:name "Cubic critical, 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) (* (* 3.0 a) c)))) (* 3.0 a)))