
(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 8 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
(fma
(/
(fma
(* -1.0546875 (* a a))
(pow c 4.0)
(* (* (fma (* c a) -0.5625 (* (* b b) -0.375)) (* c c)) (* b b)))
(pow b 7.0))
a
(* (/ c b) -0.5)))
double code(double a, double b, double c) {
return fma((fma((-1.0546875 * (a * a)), pow(c, 4.0), ((fma((c * a), -0.5625, ((b * b) * -0.375)) * (c * c)) * (b * b))) / pow(b, 7.0)), a, ((c / b) * -0.5));
}
function code(a, b, c) return fma(Float64(fma(Float64(-1.0546875 * Float64(a * a)), (c ^ 4.0), Float64(Float64(fma(Float64(c * a), -0.5625, Float64(Float64(b * b) * -0.375)) * Float64(c * c)) * Float64(b * b))) / (b ^ 7.0)), a, Float64(Float64(c / b) * -0.5)) end
code[a_, b_, c_] := N[(N[(N[(N[(-1.0546875 * N[(a * a), $MachinePrecision]), $MachinePrecision] * N[Power[c, 4.0], $MachinePrecision] + N[(N[(N[(N[(c * a), $MachinePrecision] * -0.5625 + N[(N[(b * b), $MachinePrecision] * -0.375), $MachinePrecision]), $MachinePrecision] * N[(c * c), $MachinePrecision]), $MachinePrecision] * N[(b * b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[Power[b, 7.0], $MachinePrecision]), $MachinePrecision] * a + N[(N[(c / b), $MachinePrecision] * -0.5), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(\frac{\mathsf{fma}\left(-1.0546875 \cdot \left(a \cdot a\right), {c}^{4}, \left(\mathsf{fma}\left(c \cdot a, -0.5625, \left(b \cdot b\right) \cdot -0.375\right) \cdot \left(c \cdot c\right)\right) \cdot \left(b \cdot b\right)\right)}{{b}^{7}}, a, \frac{c}{b} \cdot -0.5\right)
\end{array}
Initial program 20.5%
Taylor expanded in a around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
Applied rewrites96.4%
Taylor expanded in b around 0
Applied rewrites96.4%
Taylor expanded in c around 0
Applied rewrites96.4%
(FPCore (a b c) :precision binary64 (fma (* (- (* a (* (/ c (pow b 5.0)) -0.5625)) (/ 0.375 (pow b 3.0))) (* c c)) a (* (/ c b) -0.5)))
double code(double a, double b, double c) {
return fma((((a * ((c / pow(b, 5.0)) * -0.5625)) - (0.375 / pow(b, 3.0))) * (c * c)), a, ((c / b) * -0.5));
}
function code(a, b, c) return fma(Float64(Float64(Float64(a * Float64(Float64(c / (b ^ 5.0)) * -0.5625)) - Float64(0.375 / (b ^ 3.0))) * Float64(c * c)), a, Float64(Float64(c / b) * -0.5)) end
code[a_, b_, c_] := N[(N[(N[(N[(a * N[(N[(c / N[Power[b, 5.0], $MachinePrecision]), $MachinePrecision] * -0.5625), $MachinePrecision]), $MachinePrecision] - N[(0.375 / N[Power[b, 3.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] * N[(c * c), $MachinePrecision]), $MachinePrecision] * a + N[(N[(c / b), $MachinePrecision] * -0.5), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(\left(a \cdot \left(\frac{c}{{b}^{5}} \cdot -0.5625\right) - \frac{0.375}{{b}^{3}}\right) \cdot \left(c \cdot c\right), a, \frac{c}{b} \cdot -0.5\right)
\end{array}
Initial program 20.5%
Taylor expanded in a around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
Applied rewrites96.4%
Taylor expanded in c around 0
Applied rewrites95.6%
(FPCore (a b c) :precision binary64 (* (fma (/ (fma (* (* a b) b) -0.375 (* (* (* a a) c) -0.5625)) (pow b 5.0)) c (/ -0.5 b)) c))
double code(double a, double b, double c) {
return fma((fma(((a * b) * b), -0.375, (((a * a) * c) * -0.5625)) / pow(b, 5.0)), c, (-0.5 / b)) * c;
}
function code(a, b, c) return Float64(fma(Float64(fma(Float64(Float64(a * b) * b), -0.375, Float64(Float64(Float64(a * a) * c) * -0.5625)) / (b ^ 5.0)), c, Float64(-0.5 / b)) * c) end
code[a_, b_, c_] := N[(N[(N[(N[(N[(N[(a * b), $MachinePrecision] * b), $MachinePrecision] * -0.375 + N[(N[(N[(a * a), $MachinePrecision] * c), $MachinePrecision] * -0.5625), $MachinePrecision]), $MachinePrecision] / N[Power[b, 5.0], $MachinePrecision]), $MachinePrecision] * c + N[(-0.5 / b), $MachinePrecision]), $MachinePrecision] * c), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(\frac{\mathsf{fma}\left(\left(a \cdot b\right) \cdot b, -0.375, \left(\left(a \cdot a\right) \cdot c\right) \cdot -0.5625\right)}{{b}^{5}}, c, \frac{-0.5}{b}\right) \cdot c
\end{array}
Initial program 20.5%
Taylor expanded in c around 0
*-commutativeN/A
lower-*.f64N/A
Applied rewrites95.2%
Taylor expanded in b around 0
Applied rewrites95.2%
(FPCore (a b c) :precision binary64 (fma (* -0.375 a) (/ (/ (* c c) (* b b)) b) (* (/ c b) -0.5)))
double code(double a, double b, double c) {
return fma((-0.375 * a), (((c * c) / (b * b)) / b), ((c / b) * -0.5));
}
function code(a, b, c) return fma(Float64(-0.375 * a), Float64(Float64(Float64(c * c) / Float64(b * b)) / b), Float64(Float64(c / b) * -0.5)) end
code[a_, b_, c_] := N[(N[(-0.375 * a), $MachinePrecision] * N[(N[(N[(c * c), $MachinePrecision] / N[(b * b), $MachinePrecision]), $MachinePrecision] / b), $MachinePrecision] + N[(N[(c / b), $MachinePrecision] * -0.5), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(-0.375 \cdot a, \frac{\frac{c \cdot c}{b \cdot b}}{b}, \frac{c}{b} \cdot -0.5\right)
\end{array}
Initial program 20.5%
Taylor expanded in a around 0
+-commutativeN/A
associate-/l*N/A
associate-*r*N/A
lower-fma.f64N/A
lower-*.f64N/A
unpow2N/A
associate-/l*N/A
lower-*.f64N/A
lower-/.f64N/A
lower-pow.f64N/A
*-commutativeN/A
lower-*.f64N/A
lower-/.f6494.1
Applied rewrites94.1%
Applied rewrites94.1%
(FPCore (a b c) :precision binary64 (/ (fma (* -0.375 a) (/ (* c c) (* b b)) (* -0.5 c)) b))
double code(double a, double b, double c) {
return fma((-0.375 * a), ((c * c) / (b * b)), (-0.5 * c)) / b;
}
function code(a, b, c) return Float64(fma(Float64(-0.375 * a), Float64(Float64(c * c) / Float64(b * b)), Float64(-0.5 * c)) / b) end
code[a_, b_, c_] := N[(N[(N[(-0.375 * a), $MachinePrecision] * N[(N[(c * c), $MachinePrecision] / N[(b * b), $MachinePrecision]), $MachinePrecision] + N[(-0.5 * c), $MachinePrecision]), $MachinePrecision] / b), $MachinePrecision]
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(-0.375 \cdot a, \frac{c \cdot c}{b \cdot b}, -0.5 \cdot c\right)}{b}
\end{array}
Initial program 20.5%
Taylor expanded in a around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
Applied rewrites96.4%
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-*.f6494.1
Applied rewrites94.1%
Applied rewrites94.1%
(FPCore (a b c) :precision binary64 (* (/ (fma (* 0.375 a) (/ c (* b b)) 0.5) (- b)) c))
double code(double a, double b, double c) {
return (fma((0.375 * a), (c / (b * b)), 0.5) / -b) * c;
}
function code(a, b, c) return Float64(Float64(fma(Float64(0.375 * a), Float64(c / Float64(b * b)), 0.5) / Float64(-b)) * c) end
code[a_, b_, c_] := N[(N[(N[(N[(0.375 * a), $MachinePrecision] * N[(c / N[(b * b), $MachinePrecision]), $MachinePrecision] + 0.5), $MachinePrecision] / (-b)), $MachinePrecision] * c), $MachinePrecision]
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(0.375 \cdot a, \frac{c}{b \cdot b}, 0.5\right)}{-b} \cdot c
\end{array}
Initial program 20.5%
Taylor expanded in c around 0
*-commutativeN/A
lower-*.f64N/A
Applied rewrites95.2%
Taylor expanded in b around -inf
Applied rewrites93.8%
(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 20.5%
Taylor expanded in a around 0
*-commutativeN/A
lower-*.f64N/A
lower-/.f6488.4
Applied rewrites88.4%
(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 20.5%
Taylor expanded in a around 0
*-commutativeN/A
lower-*.f64N/A
lower-/.f6488.4
Applied rewrites88.4%
Applied rewrites88.1%
herbie shell --seed 2024338
(FPCore (a b c)
:name "Cubic critical, 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) (* (* 3.0 a) c)))) (* 3.0 a)))