
(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 (fma -0.5625 (/ (pow c 3.0) (/ (pow b 5.0) (* a a))) (fma -0.16666666666666666 (* (/ (pow (* c a) 4.0) a) (/ 6.328125 (pow b 7.0))) (fma -0.5 (/ c b) (* -0.375 (/ (* c c) (/ (pow b 3.0) a)))))))
double code(double a, double b, double c) {
return fma(-0.5625, (pow(c, 3.0) / (pow(b, 5.0) / (a * a))), fma(-0.16666666666666666, ((pow((c * a), 4.0) / a) * (6.328125 / pow(b, 7.0))), fma(-0.5, (c / b), (-0.375 * ((c * c) / (pow(b, 3.0) / a))))));
}
function code(a, b, c) return fma(-0.5625, Float64((c ^ 3.0) / Float64((b ^ 5.0) / Float64(a * a))), fma(-0.16666666666666666, Float64(Float64((Float64(c * a) ^ 4.0) / a) * Float64(6.328125 / (b ^ 7.0))), fma(-0.5, Float64(c / b), Float64(-0.375 * Float64(Float64(c * c) / Float64((b ^ 3.0) / a)))))) 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[(-0.16666666666666666 * N[(N[(N[Power[N[(c * a), $MachinePrecision], 4.0], $MachinePrecision] / a), $MachinePrecision] * N[(6.328125 / N[Power[b, 7.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(-0.5 * N[(c / b), $MachinePrecision] + N[(-0.375 * N[(N[(c * c), $MachinePrecision] / N[(N[Power[b, 3.0], $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(-0.5625, \frac{{c}^{3}}{\frac{{b}^{5}}{a \cdot a}}, \mathsf{fma}\left(-0.16666666666666666, \frac{{\left(c \cdot a\right)}^{4}}{a} \cdot \frac{6.328125}{{b}^{7}}, \mathsf{fma}\left(-0.5, \frac{c}{b}, -0.375 \cdot \frac{c \cdot c}{\frac{{b}^{3}}{a}}\right)\right)\right)
\end{array}
Initial program 16.5%
/-rgt-identity16.5%
metadata-eval16.5%
associate-/l*16.5%
associate-*r/16.5%
*-commutative16.5%
associate-*l/16.5%
associate-*r/16.5%
metadata-eval16.5%
metadata-eval16.5%
times-frac16.5%
neg-mul-116.5%
distribute-rgt-neg-in16.5%
times-frac16.5%
metadata-eval16.5%
neg-mul-116.5%
Simplified16.4%
Taylor expanded in b around inf 98.4%
fma-def98.4%
associate-/l*98.4%
unpow298.4%
fma-def98.4%
Simplified98.4%
Taylor expanded in c around 0 98.4%
distribute-rgt-out98.4%
associate-*r*98.4%
times-frac98.4%
Simplified98.4%
Final simplification98.4%
(FPCore (a b c)
:precision binary64
(fma
-0.16666666666666666
(* (/ (pow (* c a) 4.0) a) (/ 6.328125 (pow b 7.0)))
(fma
-0.5
(/ c b)
(*
a
(+
(* -0.375 (/ (* c c) (pow b 3.0)))
(* -0.5625 (* a (/ (pow c 3.0) (pow b 5.0)))))))))
double code(double a, double b, double c) {
return fma(-0.16666666666666666, ((pow((c * a), 4.0) / a) * (6.328125 / pow(b, 7.0))), fma(-0.5, (c / b), (a * ((-0.375 * ((c * c) / pow(b, 3.0))) + (-0.5625 * (a * (pow(c, 3.0) / pow(b, 5.0))))))));
}
function code(a, b, c) return fma(-0.16666666666666666, Float64(Float64((Float64(c * a) ^ 4.0) / a) * Float64(6.328125 / (b ^ 7.0))), fma(-0.5, Float64(c / b), Float64(a * Float64(Float64(-0.375 * Float64(Float64(c * c) / (b ^ 3.0))) + Float64(-0.5625 * Float64(a * Float64((c ^ 3.0) / (b ^ 5.0)))))))) end
code[a_, b_, c_] := N[(-0.16666666666666666 * N[(N[(N[Power[N[(c * a), $MachinePrecision], 4.0], $MachinePrecision] / a), $MachinePrecision] * N[(6.328125 / N[Power[b, 7.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(-0.5 * N[(c / b), $MachinePrecision] + N[(a * N[(N[(-0.375 * N[(N[(c * c), $MachinePrecision] / N[Power[b, 3.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(-0.5625 * N[(a * N[(N[Power[c, 3.0], $MachinePrecision] / N[Power[b, 5.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(-0.16666666666666666, \frac{{\left(c \cdot a\right)}^{4}}{a} \cdot \frac{6.328125}{{b}^{7}}, \mathsf{fma}\left(-0.5, \frac{c}{b}, a \cdot \left(-0.375 \cdot \frac{c \cdot c}{{b}^{3}} + -0.5625 \cdot \left(a \cdot \frac{{c}^{3}}{{b}^{5}}\right)\right)\right)\right)
\end{array}
Initial program 16.5%
neg-sub016.5%
associate-+l-16.5%
sub0-neg16.5%
neg-mul-116.5%
associate-*r/16.5%
*-commutative16.5%
metadata-eval16.5%
metadata-eval16.5%
times-frac16.5%
*-commutative16.5%
times-frac16.5%
Simplified16.4%
div-inv16.4%
Applied egg-rr16.4%
Taylor expanded in b around inf 98.4%
Simplified98.4%
Final simplification98.4%
(FPCore (a b c)
:precision binary64
(fma
-0.5
(/ c b)
(*
a
(+
(* -0.375 (/ (* c c) (pow b 3.0)))
(* -0.5625 (* a (/ (pow c 3.0) (pow b 5.0))))))))
double code(double a, double b, double c) {
return fma(-0.5, (c / b), (a * ((-0.375 * ((c * c) / pow(b, 3.0))) + (-0.5625 * (a * (pow(c, 3.0) / pow(b, 5.0)))))));
}
function code(a, b, c) return fma(-0.5, Float64(c / b), Float64(a * Float64(Float64(-0.375 * Float64(Float64(c * c) / (b ^ 3.0))) + Float64(-0.5625 * Float64(a * Float64((c ^ 3.0) / (b ^ 5.0))))))) end
code[a_, b_, c_] := N[(-0.5 * N[(c / b), $MachinePrecision] + N[(a * N[(N[(-0.375 * N[(N[(c * c), $MachinePrecision] / N[Power[b, 3.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(-0.5625 * N[(a * N[(N[Power[c, 3.0], $MachinePrecision] / N[Power[b, 5.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(-0.5, \frac{c}{b}, a \cdot \left(-0.375 \cdot \frac{c \cdot c}{{b}^{3}} + -0.5625 \cdot \left(a \cdot \frac{{c}^{3}}{{b}^{5}}\right)\right)\right)
\end{array}
Initial program 16.5%
neg-sub016.5%
associate-+l-16.5%
sub0-neg16.5%
neg-mul-116.5%
associate-*r/16.5%
*-commutative16.5%
metadata-eval16.5%
metadata-eval16.5%
times-frac16.5%
*-commutative16.5%
times-frac16.5%
Simplified16.4%
div-inv16.4%
Applied egg-rr16.4%
Taylor expanded in b around inf 97.9%
+-commutative97.9%
associate-+l+97.9%
fma-def97.9%
unpow297.9%
associate-*l/97.9%
associate-*r*97.9%
associate-*l/97.9%
unpow297.9%
associate-*r*97.9%
associate-*r*97.9%
distribute-rgt-out97.9%
Simplified97.9%
Final simplification97.9%
(FPCore (a b c) :precision binary64 (fma -0.375 (/ (* c c) (/ (pow b 3.0) a)) (* -0.5 (/ c b))))
double code(double a, double b, double c) {
return fma(-0.375, ((c * c) / (pow(b, 3.0) / a)), (-0.5 * (c / b)));
}
function code(a, b, c) return fma(-0.375, Float64(Float64(c * c) / Float64((b ^ 3.0) / a)), Float64(-0.5 * Float64(c / b))) end
code[a_, b_, c_] := N[(-0.375 * N[(N[(c * c), $MachinePrecision] / N[(N[Power[b, 3.0], $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision] + N[(-0.5 * N[(c / b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(-0.375, \frac{c \cdot c}{\frac{{b}^{3}}{a}}, -0.5 \cdot \frac{c}{b}\right)
\end{array}
Initial program 16.5%
/-rgt-identity16.5%
metadata-eval16.5%
associate-/l*16.5%
associate-*r/16.5%
*-commutative16.5%
associate-*l/16.5%
associate-*r/16.5%
metadata-eval16.5%
metadata-eval16.5%
times-frac16.5%
neg-mul-116.5%
distribute-rgt-neg-in16.5%
times-frac16.5%
metadata-eval16.5%
neg-mul-116.5%
Simplified16.4%
Taylor expanded in b around inf 96.5%
+-commutative96.5%
fma-def96.5%
associate-/l*96.5%
unpow296.5%
Simplified96.5%
Final simplification96.5%
(FPCore (a b c) :precision binary64 (* -0.3333333333333333 (/ (* a (+ (* c (/ 1.5 b)) (* a (/ c (/ (pow b 3.0) (* c 1.125)))))) a)))
double code(double a, double b, double c) {
return -0.3333333333333333 * ((a * ((c * (1.5 / b)) + (a * (c / (pow(b, 3.0) / (c * 1.125)))))) / a);
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
code = (-0.3333333333333333d0) * ((a * ((c * (1.5d0 / b)) + (a * (c / ((b ** 3.0d0) / (c * 1.125d0)))))) / a)
end function
public static double code(double a, double b, double c) {
return -0.3333333333333333 * ((a * ((c * (1.5 / b)) + (a * (c / (Math.pow(b, 3.0) / (c * 1.125)))))) / a);
}
def code(a, b, c): return -0.3333333333333333 * ((a * ((c * (1.5 / b)) + (a * (c / (math.pow(b, 3.0) / (c * 1.125)))))) / a)
function code(a, b, c) return Float64(-0.3333333333333333 * Float64(Float64(a * Float64(Float64(c * Float64(1.5 / b)) + Float64(a * Float64(c / Float64((b ^ 3.0) / Float64(c * 1.125)))))) / a)) end
function tmp = code(a, b, c) tmp = -0.3333333333333333 * ((a * ((c * (1.5 / b)) + (a * (c / ((b ^ 3.0) / (c * 1.125)))))) / a); end
code[a_, b_, c_] := N[(-0.3333333333333333 * N[(N[(a * N[(N[(c * N[(1.5 / b), $MachinePrecision]), $MachinePrecision] + N[(a * N[(c / N[(N[Power[b, 3.0], $MachinePrecision] / N[(c * 1.125), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
-0.3333333333333333 \cdot \frac{a \cdot \left(c \cdot \frac{1.5}{b} + a \cdot \frac{c}{\frac{{b}^{3}}{c \cdot 1.125}}\right)}{a}
\end{array}
Initial program 16.5%
/-rgt-identity16.5%
metadata-eval16.5%
associate-/l*16.5%
associate-*r/16.5%
*-commutative16.5%
associate-*l/16.5%
associate-*r/16.5%
metadata-eval16.5%
metadata-eval16.5%
times-frac16.5%
neg-mul-116.5%
distribute-rgt-neg-in16.5%
times-frac16.5%
metadata-eval16.5%
neg-mul-116.5%
Simplified16.4%
Taylor expanded in b around inf 95.8%
fma-def95.8%
associate-*r/95.8%
associate-*r*95.8%
unpow295.8%
unpow295.8%
Simplified95.8%
Taylor expanded in c around 0 95.8%
associate-/l*95.8%
associate-/r/95.9%
associate-*r*95.9%
unpow295.9%
associate-/l*95.9%
associate-*r/95.9%
*-commutative95.9%
unpow295.9%
associate-/r/95.9%
associate-*r*95.9%
distribute-rgt-out95.9%
associate-*r/95.9%
associate-*l/95.9%
*-commutative95.9%
Simplified95.9%
Final simplification95.9%
(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 16.5%
/-rgt-identity16.5%
metadata-eval16.5%
associate-/l*16.5%
associate-*r/16.5%
*-commutative16.5%
associate-*l/16.5%
associate-*r/16.5%
metadata-eval16.5%
metadata-eval16.5%
times-frac16.5%
neg-mul-116.5%
distribute-rgt-neg-in16.5%
times-frac16.5%
metadata-eval16.5%
neg-mul-116.5%
Simplified16.4%
Taylor expanded in b around inf 91.7%
Final simplification91.7%
herbie shell --seed 2023200
(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)))