
(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 4 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 -0.5625 (* a (* a (/ (pow c 3.0) (pow b 5.0)))) (fma -0.16666666666666666 (/ (* (pow (* a c) 4.0) 6.328125) (* a (pow b 7.0))) (fma -0.5 (/ c b) (* a (* (/ c (/ (pow b 3.0) c)) -0.375))))))
double code(double a, double b, double c) {
return fma(-0.5625, (a * (a * (pow(c, 3.0) / pow(b, 5.0)))), fma(-0.16666666666666666, ((pow((a * c), 4.0) * 6.328125) / (a * pow(b, 7.0))), fma(-0.5, (c / b), (a * ((c / (pow(b, 3.0) / c)) * -0.375)))));
}
function code(a, b, c) return fma(-0.5625, Float64(a * Float64(a * Float64((c ^ 3.0) / (b ^ 5.0)))), fma(-0.16666666666666666, Float64(Float64((Float64(a * c) ^ 4.0) * 6.328125) / Float64(a * (b ^ 7.0))), fma(-0.5, Float64(c / b), Float64(a * Float64(Float64(c / Float64((b ^ 3.0) / c)) * -0.375))))) end
code[a_, b_, c_] := N[(-0.5625 * N[(a * N[(a * N[(N[Power[c, 3.0], $MachinePrecision] / N[Power[b, 5.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(-0.16666666666666666 * N[(N[(N[Power[N[(a * c), $MachinePrecision], 4.0], $MachinePrecision] * 6.328125), $MachinePrecision] / N[(a * N[Power[b, 7.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(-0.5 * N[(c / b), $MachinePrecision] + N[(a * N[(N[(c / N[(N[Power[b, 3.0], $MachinePrecision] / c), $MachinePrecision]), $MachinePrecision] * -0.375), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(-0.5625, a \cdot \left(a \cdot \frac{{c}^{3}}{{b}^{5}}\right), \mathsf{fma}\left(-0.16666666666666666, \frac{{\left(a \cdot c\right)}^{4} \cdot 6.328125}{a \cdot {b}^{7}}, \mathsf{fma}\left(-0.5, \frac{c}{b}, a \cdot \left(\frac{c}{\frac{{b}^{3}}{c}} \cdot -0.375\right)\right)\right)\right)
\end{array}
Initial program 16.7%
neg-sub016.7%
associate-+l-16.7%
sub0-neg16.7%
neg-mul-116.7%
associate-*r/16.7%
*-commutative16.7%
metadata-eval16.7%
metadata-eval16.7%
times-frac16.7%
*-commutative16.7%
times-frac16.7%
Simplified16.9%
add-exp-log16.9%
Applied egg-rr16.9%
Taylor expanded in b around inf 98.9%
Simplified98.9%
Final simplification98.9%
(FPCore (a b c) :precision binary64 (fma -0.5625 (/ (pow c 3.0) (/ (pow b 5.0) (* a a))) (+ (* -0.375 (/ (* c c) (/ (pow b 3.0) a))) (* -0.5 (/ c b)))))
double code(double a, double b, double c) {
return fma(-0.5625, (pow(c, 3.0) / (pow(b, 5.0) / (a * a))), ((-0.375 * ((c * c) / (pow(b, 3.0) / a))) + (-0.5 * (c / b))));
}
function code(a, b, c) return fma(-0.5625, Float64((c ^ 3.0) / Float64((b ^ 5.0) / Float64(a * a))), Float64(Float64(-0.375 * Float64(Float64(c * c) / Float64((b ^ 3.0) / a))) + Float64(-0.5 * Float64(c / b)))) end
code[a_, b_, c_] := N[(-0.5625 * N[(N[Power[c, 3.0], $MachinePrecision] / N[(N[Power[b, 5.0], $MachinePrecision] / N[(a * a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(N[(-0.375 * N[(N[(c * c), $MachinePrecision] / N[(N[Power[b, 3.0], $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(-0.5 * N[(c / b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(-0.5625, \frac{{c}^{3}}{\frac{{b}^{5}}{a \cdot a}}, -0.375 \cdot \frac{c \cdot c}{\frac{{b}^{3}}{a}} + -0.5 \cdot \frac{c}{b}\right)
\end{array}
Initial program 16.7%
neg-sub016.7%
associate-+l-16.7%
sub0-neg16.7%
neg-mul-116.7%
associate-*r/16.7%
*-commutative16.7%
metadata-eval16.7%
metadata-eval16.7%
times-frac16.7%
*-commutative16.7%
times-frac16.7%
Simplified16.9%
Taylor expanded in b around inf 98.3%
fma-def98.3%
associate-/l*98.3%
unpow298.3%
+-commutative98.3%
fma-def98.3%
associate-/l*98.3%
unpow298.3%
Simplified98.3%
fma-udef96.8%
Applied egg-rr98.3%
Final simplification98.3%
(FPCore (a b c) :precision binary64 (+ (* -0.375 (/ (* c c) (/ (pow b 3.0) a))) (* -0.5 (/ c b))))
double code(double a, double b, double c) {
return (-0.375 * ((c * c) / (pow(b, 3.0) / a))) + (-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 = ((-0.375d0) * ((c * c) / ((b ** 3.0d0) / a))) + ((-0.5d0) * (c / b))
end function
public static double code(double a, double b, double c) {
return (-0.375 * ((c * c) / (Math.pow(b, 3.0) / a))) + (-0.5 * (c / b));
}
def code(a, b, c): return (-0.375 * ((c * c) / (math.pow(b, 3.0) / a))) + (-0.5 * (c / b))
function code(a, b, c) return Float64(Float64(-0.375 * Float64(Float64(c * c) / Float64((b ^ 3.0) / a))) + Float64(-0.5 * Float64(c / b))) end
function tmp = code(a, b, c) tmp = (-0.375 * ((c * c) / ((b ^ 3.0) / a))) + (-0.5 * (c / b)); end
code[a_, b_, c_] := N[(N[(-0.375 * N[(N[(c * c), $MachinePrecision] / N[(N[Power[b, 3.0], $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(-0.5 * N[(c / b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
-0.375 \cdot \frac{c \cdot c}{\frac{{b}^{3}}{a}} + -0.5 \cdot \frac{c}{b}
\end{array}
Initial program 16.7%
neg-sub016.7%
associate-+l-16.7%
sub0-neg16.7%
neg-mul-116.7%
associate-*r/16.7%
*-commutative16.7%
metadata-eval16.7%
metadata-eval16.7%
times-frac16.7%
*-commutative16.7%
times-frac16.7%
Simplified16.9%
Taylor expanded in b around inf 96.8%
+-commutative96.8%
fma-def96.8%
associate-/l*96.8%
unpow296.8%
Simplified96.8%
fma-udef96.8%
Applied egg-rr96.8%
Final simplification96.8%
(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 16.7%
neg-sub016.7%
associate-+l-16.7%
sub0-neg16.7%
neg-mul-116.7%
associate-*r/16.7%
*-commutative16.7%
metadata-eval16.7%
metadata-eval16.7%
times-frac16.7%
*-commutative16.7%
times-frac16.7%
Simplified16.9%
Taylor expanded in b around inf 91.6%
Final simplification91.6%
herbie shell --seed 2023182
(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)))