
(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
(/ c b)
-0.5
(*
(*
(fma
(* (* (fma (* c a) -0.5625 (* (* b b) -0.375)) c) c)
(* b b)
(* (pow c 4.0) (* -1.0546875 (* a a))))
(pow b -7.0))
a)))
double code(double a, double b, double c) {
return fma((c / b), -0.5, ((fma(((fma((c * a), -0.5625, ((b * b) * -0.375)) * c) * c), (b * b), (pow(c, 4.0) * (-1.0546875 * (a * a)))) * pow(b, -7.0)) * a));
}
function code(a, b, c) return fma(Float64(c / b), -0.5, Float64(Float64(fma(Float64(Float64(fma(Float64(c * a), -0.5625, Float64(Float64(b * b) * -0.375)) * c) * c), Float64(b * b), Float64((c ^ 4.0) * Float64(-1.0546875 * Float64(a * a)))) * (b ^ -7.0)) * a)) end
code[a_, b_, c_] := N[(N[(c / b), $MachinePrecision] * -0.5 + N[(N[(N[(N[(N[(N[(N[(c * a), $MachinePrecision] * -0.5625 + N[(N[(b * b), $MachinePrecision] * -0.375), $MachinePrecision]), $MachinePrecision] * c), $MachinePrecision] * c), $MachinePrecision] * N[(b * b), $MachinePrecision] + N[(N[Power[c, 4.0], $MachinePrecision] * N[(-1.0546875 * N[(a * a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] * N[Power[b, -7.0], $MachinePrecision]), $MachinePrecision] * a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(\frac{c}{b}, -0.5, \left(\mathsf{fma}\left(\left(\mathsf{fma}\left(c \cdot a, -0.5625, \left(b \cdot b\right) \cdot -0.375\right) \cdot c\right) \cdot c, b \cdot b, {c}^{4} \cdot \left(-1.0546875 \cdot \left(a \cdot a\right)\right)\right) \cdot {b}^{-7}\right) \cdot a\right)
\end{array}
Initial program 15.9%
Taylor expanded in a around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
Applied rewrites97.5%
Taylor expanded in b around 0
Applied rewrites97.5%
Taylor expanded in c around 0
Applied rewrites97.5%
Applied rewrites97.5%
Final simplification97.5%
(FPCore (a b c) :precision binary64 (fma (* (* c c) (fma (* -0.5625 a) (/ c (pow b 5.0)) (/ -0.375 (pow b 3.0)))) a (* -0.5 (/ c b))))
double code(double a, double b, double c) {
return fma(((c * c) * fma((-0.5625 * a), (c / pow(b, 5.0)), (-0.375 / pow(b, 3.0)))), a, (-0.5 * (c / b)));
}
function code(a, b, c) return fma(Float64(Float64(c * c) * fma(Float64(-0.5625 * a), Float64(c / (b ^ 5.0)), Float64(-0.375 / (b ^ 3.0)))), a, Float64(-0.5 * Float64(c / b))) end
code[a_, b_, c_] := N[(N[(N[(c * c), $MachinePrecision] * N[(N[(-0.5625 * a), $MachinePrecision] * N[(c / N[Power[b, 5.0], $MachinePrecision]), $MachinePrecision] + N[(-0.375 / N[Power[b, 3.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] * a + N[(-0.5 * N[(c / b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(\left(c \cdot c\right) \cdot \mathsf{fma}\left(-0.5625 \cdot a, \frac{c}{{b}^{5}}, \frac{-0.375}{{b}^{3}}\right), a, -0.5 \cdot \frac{c}{b}\right)
\end{array}
Initial program 15.9%
Taylor expanded in a around 0
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
Applied rewrites97.5%
Taylor expanded in c around 0
Applied rewrites96.8%
Final simplification96.8%
(FPCore (a b c)
:precision binary64
(/
0.3333333333333333
(*
(- b)
(+
(fma (/ a (* b b)) -0.5 (/ 0.6666666666666666 c))
(/ (* (* (* a a) c) -0.375) (pow b 4.0))))))
double code(double a, double b, double c) {
return 0.3333333333333333 / (-b * (fma((a / (b * b)), -0.5, (0.6666666666666666 / c)) + ((((a * a) * c) * -0.375) / pow(b, 4.0))));
}
function code(a, b, c) return Float64(0.3333333333333333 / Float64(Float64(-b) * Float64(fma(Float64(a / Float64(b * b)), -0.5, Float64(0.6666666666666666 / c)) + Float64(Float64(Float64(Float64(a * a) * c) * -0.375) / (b ^ 4.0))))) end
code[a_, b_, c_] := N[(0.3333333333333333 / N[((-b) * N[(N[(N[(a / N[(b * b), $MachinePrecision]), $MachinePrecision] * -0.5 + N[(0.6666666666666666 / c), $MachinePrecision]), $MachinePrecision] + N[(N[(N[(N[(a * a), $MachinePrecision] * c), $MachinePrecision] * -0.375), $MachinePrecision] / N[Power[b, 4.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{0.3333333333333333}{\left(-b\right) \cdot \left(\mathsf{fma}\left(\frac{a}{b \cdot b}, -0.5, \frac{0.6666666666666666}{c}\right) + \frac{\left(\left(a \cdot a\right) \cdot c\right) \cdot -0.375}{{b}^{4}}\right)}
\end{array}
Initial program 15.9%
lift-/.f64N/A
div-invN/A
lift-+.f64N/A
flip3-+N/A
clear-numN/A
lift-*.f64N/A
associate-/r*N/A
frac-timesN/A
Applied rewrites15.9%
Taylor expanded in b around inf
*-commutativeN/A
lower-*.f64N/A
Applied rewrites96.5%
Final simplification96.5%
(FPCore (a b c) :precision binary64 (* (fma (/ (fma (* (* b b) a) -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(((b * b) * a), -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(b * b) * a), -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[(b * b), $MachinePrecision] * a), $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(b \cdot b\right) \cdot a, -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 15.9%
Taylor expanded in c around 0
*-commutativeN/A
lower-*.f64N/A
Applied rewrites96.4%
Taylor expanded in b around 0
Applied rewrites96.4%
(FPCore (a b c) :precision binary64 (/ (fma (/ (* (* c c) -0.375) b) (/ a b) (* -0.5 c)) b))
double code(double a, double b, double c) {
return fma((((c * c) * -0.375) / b), (a / b), (-0.5 * c)) / b;
}
function code(a, b, c) return Float64(fma(Float64(Float64(Float64(c * c) * -0.375) / b), Float64(a / b), Float64(-0.5 * c)) / b) end
code[a_, b_, c_] := N[(N[(N[(N[(N[(c * c), $MachinePrecision] * -0.375), $MachinePrecision] / b), $MachinePrecision] * N[(a / b), $MachinePrecision] + N[(-0.5 * c), $MachinePrecision]), $MachinePrecision] / b), $MachinePrecision]
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\frac{\left(c \cdot c\right) \cdot -0.375}{b}, \frac{a}{b}, -0.5 \cdot c\right)}{b}
\end{array}
Initial program 15.9%
Taylor expanded in b around inf
lower-/.f64N/A
+-commutativeN/A
associate-*r/N/A
unpow2N/A
*-commutativeN/A
associate-*r*N/A
times-fracN/A
lower-fma.f64N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f64N/A
unpow2N/A
lower-*.f64N/A
lower-/.f64N/A
lower-*.f6495.4
Applied rewrites95.4%
(FPCore (a b c) :precision binary64 (/ 0.3333333333333333 (fma -0.6666666666666666 (/ b c) (* 0.5 (/ a b)))))
double code(double a, double b, double c) {
return 0.3333333333333333 / fma(-0.6666666666666666, (b / c), (0.5 * (a / b)));
}
function code(a, b, c) return Float64(0.3333333333333333 / fma(-0.6666666666666666, Float64(b / c), Float64(0.5 * Float64(a / b)))) end
code[a_, b_, c_] := N[(0.3333333333333333 / N[(-0.6666666666666666 * N[(b / c), $MachinePrecision] + N[(0.5 * N[(a / b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{0.3333333333333333}{\mathsf{fma}\left(-0.6666666666666666, \frac{b}{c}, 0.5 \cdot \frac{a}{b}\right)}
\end{array}
Initial program 15.9%
lift-/.f64N/A
div-invN/A
lift-+.f64N/A
flip3-+N/A
clear-numN/A
lift-*.f64N/A
associate-/r*N/A
frac-timesN/A
Applied rewrites15.9%
Taylor expanded in a around 0
lower-fma.f64N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f64N/A
lower-/.f6495.2
Applied rewrites95.2%
Final simplification95.2%
(FPCore (a b c) :precision binary64 (* -0.5 (/ c b)))
double code(double a, double b, double c) {
return -0.5 * (c / b);
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
code = (-0.5d0) * (c / b)
end function
public static double code(double a, double b, double c) {
return -0.5 * (c / b);
}
def code(a, b, c): return -0.5 * (c / b)
function code(a, b, c) return Float64(-0.5 * Float64(c / b)) end
function tmp = code(a, b, c) tmp = -0.5 * (c / b); end
code[a_, b_, c_] := N[(-0.5 * N[(c / b), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
-0.5 \cdot \frac{c}{b}
\end{array}
Initial program 15.9%
Taylor expanded in c around 0
*-commutativeN/A
lower-*.f64N/A
lower-/.f6491.4
Applied rewrites91.4%
Final simplification91.4%
(FPCore (a b c) :precision binary64 (* (/ -0.5 b) c))
double code(double a, double b, double c) {
return (-0.5 / b) * c;
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
code = ((-0.5d0) / b) * c
end function
public static double code(double a, double b, double c) {
return (-0.5 / b) * c;
}
def code(a, b, c): return (-0.5 / b) * c
function code(a, b, c) return Float64(Float64(-0.5 / b) * c) end
function tmp = code(a, b, c) tmp = (-0.5 / b) * c; end
code[a_, b_, c_] := N[(N[(-0.5 / b), $MachinePrecision] * c), $MachinePrecision]
\begin{array}{l}
\\
\frac{-0.5}{b} \cdot c
\end{array}
Initial program 15.9%
Taylor expanded in c around 0
*-commutativeN/A
lower-*.f64N/A
Applied rewrites96.4%
Taylor expanded in c around 0
Applied rewrites91.1%
herbie shell --seed 2024248
(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)))