
(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 7 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 -0.3333333333333333) a) (/ 0.3333333333333333 a)) (+ b (sqrt (fma a (* -3.0 c) (* b b))))))
double code(double a, double b, double c) {
return (((c * -0.3333333333333333) / a) / (0.3333333333333333 / a)) / (b + sqrt(fma(a, (-3.0 * c), (b * b))));
}
function code(a, b, c) return Float64(Float64(Float64(Float64(c * -0.3333333333333333) / a) / Float64(0.3333333333333333 / a)) / Float64(b + sqrt(fma(a, Float64(-3.0 * c), Float64(b * b))))) end
code[a_, b_, c_] := N[(N[(N[(N[(c * -0.3333333333333333), $MachinePrecision] / a), $MachinePrecision] / N[(0.3333333333333333 / a), $MachinePrecision]), $MachinePrecision] / N[(b + N[Sqrt[N[(a * N[(-3.0 * c), $MachinePrecision] + N[(b * b), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\frac{\frac{c \cdot -0.3333333333333333}{a}}{\frac{0.3333333333333333}{a}}}{b + \sqrt{\mathsf{fma}\left(a, -3 \cdot c, b \cdot b\right)}}
\end{array}
Initial program 19.4%
lift-/.f64N/A
lift-+.f64N/A
+-commutativeN/A
lift-neg.f64N/A
unsub-negN/A
div-subN/A
lower--.f64N/A
Applied rewrites19.3%
Applied rewrites19.8%
Taylor expanded in c around 0
associate-*r/N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f6499.1
Applied rewrites99.1%
lift-/.f64N/A
lift-/.f64N/A
clear-numN/A
lift-*.f64N/A
associate-/r*N/A
Applied rewrites99.3%
(FPCore (a b c) :precision binary64 (* a (/ (/ (* c -0.3333333333333333) a) (* 0.3333333333333333 (+ b (sqrt (fma a (* -3.0 c) (* b b))))))))
double code(double a, double b, double c) {
return a * (((c * -0.3333333333333333) / a) / (0.3333333333333333 * (b + sqrt(fma(a, (-3.0 * c), (b * b))))));
}
function code(a, b, c) return Float64(a * Float64(Float64(Float64(c * -0.3333333333333333) / a) / Float64(0.3333333333333333 * Float64(b + sqrt(fma(a, Float64(-3.0 * c), Float64(b * b))))))) end
code[a_, b_, c_] := N[(a * N[(N[(N[(c * -0.3333333333333333), $MachinePrecision] / a), $MachinePrecision] / N[(0.3333333333333333 * N[(b + N[Sqrt[N[(a * N[(-3.0 * c), $MachinePrecision] + N[(b * b), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
a \cdot \frac{\frac{c \cdot -0.3333333333333333}{a}}{0.3333333333333333 \cdot \left(b + \sqrt{\mathsf{fma}\left(a, -3 \cdot c, b \cdot b\right)}\right)}
\end{array}
Initial program 19.4%
lift-/.f64N/A
lift-+.f64N/A
+-commutativeN/A
lift-neg.f64N/A
unsub-negN/A
div-subN/A
lower--.f64N/A
Applied rewrites19.3%
Applied rewrites19.8%
Taylor expanded in c around 0
associate-*r/N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f6499.1
Applied rewrites99.1%
lift-/.f64N/A
lift-/.f64N/A
clear-numN/A
lift-*.f64N/A
lift-/.f64N/A
associate-*l/N/A
Applied rewrites99.1%
Final simplification99.1%
(FPCore (a b c) :precision binary64 (/ (fma a (/ (* (* c c) -0.375) (* b b)) (* c -0.5)) b))
double code(double a, double b, double c) {
return fma(a, (((c * c) * -0.375) / (b * b)), (c * -0.5)) / b;
}
function code(a, b, c) return Float64(fma(a, Float64(Float64(Float64(c * c) * -0.375) / Float64(b * b)), Float64(c * -0.5)) / b) end
code[a_, b_, c_] := N[(N[(a * N[(N[(N[(c * c), $MachinePrecision] * -0.375), $MachinePrecision] / N[(b * b), $MachinePrecision]), $MachinePrecision] + N[(c * -0.5), $MachinePrecision]), $MachinePrecision] / b), $MachinePrecision]
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(a, \frac{\left(c \cdot c\right) \cdot -0.375}{b \cdot b}, c \cdot -0.5\right)}{b}
\end{array}
Initial program 19.4%
Taylor expanded in b around inf
lower-/.f64N/A
Applied rewrites94.4%
(FPCore (a b c) :precision binary64 (/ 1.0 (fma 1.5 (/ a b) (/ (* b -2.0) c))))
double code(double a, double b, double c) {
return 1.0 / fma(1.5, (a / b), ((b * -2.0) / c));
}
function code(a, b, c) return Float64(1.0 / fma(1.5, Float64(a / b), Float64(Float64(b * -2.0) / c))) end
code[a_, b_, c_] := N[(1.0 / N[(1.5 * N[(a / b), $MachinePrecision] + N[(N[(b * -2.0), $MachinePrecision] / c), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{1}{\mathsf{fma}\left(1.5, \frac{a}{b}, \frac{b \cdot -2}{c}\right)}
\end{array}
Initial program 19.4%
lift-/.f64N/A
lift-+.f64N/A
+-commutativeN/A
lift-neg.f64N/A
unsub-negN/A
div-subN/A
lower--.f64N/A
Applied rewrites19.3%
Applied rewrites19.8%
Taylor expanded in a around 0
+-commutativeN/A
lower-fma.f64N/A
lower-/.f64N/A
associate-*r/N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f6494.3
Applied rewrites94.3%
(FPCore (a b c) :precision binary64 (* c (/ (fma -0.375 (* a (/ c (* b b))) -0.5) b)))
double code(double a, double b, double c) {
return c * (fma(-0.375, (a * (c / (b * b))), -0.5) / b);
}
function code(a, b, c) return Float64(c * Float64(fma(-0.375, Float64(a * Float64(c / Float64(b * b))), -0.5) / b)) end
code[a_, b_, c_] := N[(c * N[(N[(-0.375 * N[(a * N[(c / N[(b * b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + -0.5), $MachinePrecision] / b), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
c \cdot \frac{\mathsf{fma}\left(-0.375, a \cdot \frac{c}{b \cdot b}, -0.5\right)}{b}
\end{array}
Initial program 19.4%
Taylor expanded in c around 0
sub-negN/A
distribute-lft-inN/A
associate-*r/N/A
associate-*r*N/A
associate-*l/N/A
associate-*r/N/A
distribute-lft-inN/A
lower-*.f64N/A
associate-*r/N/A
associate-*l/N/A
associate-*r*N/A
associate-*r/N/A
*-commutativeN/A
Applied rewrites94.1%
Taylor expanded in b around inf
Applied rewrites94.0%
(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 19.4%
Taylor expanded in b around inf
lower-*.f64N/A
lower-/.f6489.2
Applied rewrites89.2%
(FPCore (a b c) :precision binary64 0.0)
double code(double a, double b, double c) {
return 0.0;
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
code = 0.0d0
end function
public static double code(double a, double b, double c) {
return 0.0;
}
def code(a, b, c): return 0.0
function code(a, b, c) return 0.0 end
function tmp = code(a, b, c) tmp = 0.0; end
code[a_, b_, c_] := 0.0
\begin{array}{l}
\\
0
\end{array}
Initial program 19.4%
lift-/.f64N/A
lift-+.f64N/A
+-commutativeN/A
lift-neg.f64N/A
unsub-negN/A
div-subN/A
lower--.f64N/A
Applied rewrites19.3%
lift--.f64N/A
lift-/.f64N/A
lift-/.f64N/A
frac-subN/A
lower-/.f64N/A
Applied rewrites20.7%
Taylor expanded in a around 0
associate-*r/N/A
distribute-rgt-outN/A
metadata-evalN/A
mul0-rgtN/A
metadata-evalN/A
lower-/.f643.3
Applied rewrites3.3%
Taylor expanded in a around 0
Applied rewrites3.3%
herbie shell --seed 2024233
(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)))