
(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 5 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
-0.5
(/ c b)
(fma
-0.16666666666666666
(* (/ (pow (* c a) 4.0) (pow b 7.0)) (/ 6.328125 a))
(*
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), fma(-0.16666666666666666, ((pow((c * a), 4.0) / pow(b, 7.0)) * (6.328125 / a)), (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), fma(-0.16666666666666666, Float64(Float64((Float64(c * a) ^ 4.0) / (b ^ 7.0)) * Float64(6.328125 / a)), Float64(a * Float64(Float64(-0.375 * Float64(c * Float64(c / (b ^ 3.0)))) + Float64(-0.5625 * Float64(Float64(a * (c ^ 3.0)) / (b ^ 5.0))))))) end
code[a_, b_, c_] := N[(-0.5 * N[(c / b), $MachinePrecision] + N[(-0.16666666666666666 * N[(N[(N[Power[N[(c * a), $MachinePrecision], 4.0], $MachinePrecision] / N[Power[b, 7.0], $MachinePrecision]), $MachinePrecision] * N[(6.328125 / a), $MachinePrecision]), $MachinePrecision] + N[(a * N[(N[(-0.375 * N[(c * N[(c / N[Power[b, 3.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(-0.5625 * N[(N[(a * N[Power[c, 3.0], $MachinePrecision]), $MachinePrecision] / N[Power[b, 5.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(-0.5, \frac{c}{b}, \mathsf{fma}\left(-0.16666666666666666, \frac{{\left(c \cdot a\right)}^{4}}{{b}^{7}} \cdot \frac{6.328125}{a}, a \cdot \left(-0.375 \cdot \left(c \cdot \frac{c}{{b}^{3}}\right) + -0.5625 \cdot \frac{a \cdot {c}^{3}}{{b}^{5}}\right)\right)\right)
\end{array}
Initial program 28.6%
/-rgt-identity28.6%
metadata-eval28.6%
associate-/l*28.6%
associate-*r/28.6%
*-commutative28.6%
associate-*l/28.6%
associate-*r/28.6%
metadata-eval28.6%
metadata-eval28.6%
times-frac28.6%
neg-mul-128.6%
distribute-rgt-neg-in28.6%
times-frac28.6%
metadata-eval28.6%
neg-mul-128.6%
Simplified28.6%
Taylor expanded in b around inf 95.2%
fma-def95.2%
associate-/l*95.2%
unpow295.2%
fma-def95.2%
associate-/l*95.2%
unpow295.2%
fma-def95.4%
Simplified95.4%
Taylor expanded in c around 0 95.6%
Simplified95.6%
Final simplification95.6%
(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(c * Float64(c / (b ^ 3.0)))) + Float64(-0.5625 * Float64(Float64(a * (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[(c * N[(c / N[Power[b, 3.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(-0.5625 * N[(N[(a * N[Power[c, 3.0], $MachinePrecision]), $MachinePrecision] / N[Power[b, 5.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(-0.5, \frac{c}{b}, a \cdot \left(-0.375 \cdot \left(c \cdot \frac{c}{{b}^{3}}\right) + -0.5625 \cdot \frac{a \cdot {c}^{3}}{{b}^{5}}\right)\right)
\end{array}
Initial program 28.6%
/-rgt-identity28.6%
metadata-eval28.6%
associate-/l*28.6%
associate-*r/28.6%
*-commutative28.6%
associate-*l/28.6%
associate-*r/28.6%
metadata-eval28.6%
metadata-eval28.6%
times-frac28.6%
neg-mul-128.6%
distribute-rgt-neg-in28.6%
times-frac28.6%
metadata-eval28.6%
neg-mul-128.6%
Simplified28.6%
Taylor expanded in b around inf 95.2%
fma-def95.2%
associate-/l*95.2%
unpow295.2%
fma-def95.2%
associate-/l*95.2%
unpow295.2%
fma-def95.4%
Simplified95.4%
Taylor expanded in c around 0 94.3%
+-commutative94.3%
associate-+l+94.3%
+-commutative94.3%
fma-def94.3%
+-commutative94.3%
associate-*l/94.3%
associate-*r*94.3%
associate-*l/94.3%
unpow294.3%
associate-*r*94.3%
associate-*r*94.3%
Simplified94.3%
Final simplification94.3%
(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(Float64(-0.5 * 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[(N[(-0.5 * c), $MachinePrecision] / b), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(-0.375, \frac{c \cdot c}{\frac{{b}^{3}}{a}}, \frac{-0.5 \cdot c}{b}\right)
\end{array}
Initial program 28.6%
/-rgt-identity28.6%
metadata-eval28.6%
associate-/l*28.6%
associate-*r/28.6%
*-commutative28.6%
associate-*l/28.6%
associate-*r/28.6%
metadata-eval28.6%
metadata-eval28.6%
times-frac28.6%
neg-mul-128.6%
distribute-rgt-neg-in28.6%
times-frac28.6%
metadata-eval28.6%
neg-mul-128.6%
Simplified28.6%
Taylor expanded in b around inf 91.6%
+-commutative91.6%
fma-def91.6%
associate-/l*91.6%
unpow291.6%
associate-*r/91.6%
Simplified91.6%
Final simplification91.6%
(FPCore (a b c) :precision binary64 (* -0.3333333333333333 (/ (+ (* 1.5 (* (/ c b) a)) (/ (* 1.125 (* a a)) (/ (pow b 3.0) (* c c)))) a)))
double code(double a, double b, double c) {
return -0.3333333333333333 * (((1.5 * ((c / b) * a)) + ((1.125 * (a * a)) / (pow(b, 3.0) / (c * c)))) / 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) * (((1.5d0 * ((c / b) * a)) + ((1.125d0 * (a * a)) / ((b ** 3.0d0) / (c * c)))) / a)
end function
public static double code(double a, double b, double c) {
return -0.3333333333333333 * (((1.5 * ((c / b) * a)) + ((1.125 * (a * a)) / (Math.pow(b, 3.0) / (c * c)))) / a);
}
def code(a, b, c): return -0.3333333333333333 * (((1.5 * ((c / b) * a)) + ((1.125 * (a * a)) / (math.pow(b, 3.0) / (c * c)))) / a)
function code(a, b, c) return Float64(-0.3333333333333333 * Float64(Float64(Float64(1.5 * Float64(Float64(c / b) * a)) + Float64(Float64(1.125 * Float64(a * a)) / Float64((b ^ 3.0) / Float64(c * c)))) / a)) end
function tmp = code(a, b, c) tmp = -0.3333333333333333 * (((1.5 * ((c / b) * a)) + ((1.125 * (a * a)) / ((b ^ 3.0) / (c * c)))) / a); end
code[a_, b_, c_] := N[(-0.3333333333333333 * N[(N[(N[(1.5 * N[(N[(c / b), $MachinePrecision] * a), $MachinePrecision]), $MachinePrecision] + N[(N[(1.125 * N[(a * a), $MachinePrecision]), $MachinePrecision] / N[(N[Power[b, 3.0], $MachinePrecision] / N[(c * c), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
-0.3333333333333333 \cdot \frac{1.5 \cdot \left(\frac{c}{b} \cdot a\right) + \frac{1.125 \cdot \left(a \cdot a\right)}{\frac{{b}^{3}}{c \cdot c}}}{a}
\end{array}
Initial program 28.6%
/-rgt-identity28.6%
metadata-eval28.6%
associate-/l*28.6%
associate-*r/28.6%
*-commutative28.6%
associate-*l/28.6%
associate-*r/28.6%
metadata-eval28.6%
metadata-eval28.6%
times-frac28.6%
neg-mul-128.6%
distribute-rgt-neg-in28.6%
times-frac28.6%
metadata-eval28.6%
neg-mul-128.6%
Simplified28.6%
Taylor expanded in b around inf 91.0%
fma-def91.1%
associate-*r/91.1%
*-commutative91.1%
associate-*r*91.1%
unpow291.1%
unpow291.1%
Simplified91.1%
fma-udef91.0%
associate-/l*91.0%
associate-/r/91.1%
associate-/l*91.1%
Applied egg-rr91.1%
Final simplification91.1%
(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(Float64(-0.5 * c) / b) end
function tmp = code(a, b, c) tmp = (-0.5 * c) / b; end
code[a_, b_, c_] := N[(N[(-0.5 * c), $MachinePrecision] / b), $MachinePrecision]
\begin{array}{l}
\\
\frac{-0.5 \cdot c}{b}
\end{array}
Initial program 28.6%
/-rgt-identity28.6%
metadata-eval28.6%
associate-/l*28.6%
associate-*r/28.6%
*-commutative28.6%
associate-*l/28.6%
associate-*r/28.6%
metadata-eval28.6%
metadata-eval28.6%
times-frac28.6%
neg-mul-128.6%
distribute-rgt-neg-in28.6%
times-frac28.6%
metadata-eval28.6%
neg-mul-128.6%
Simplified28.6%
Taylor expanded in b around inf 83.8%
associate-*r/83.8%
Simplified83.8%
Final simplification83.8%
herbie shell --seed 2023257
(FPCore (a b c)
:name "Cubic critical, medium range"
:precision binary64
:pre (and (and (and (< 1.1102230246251565e-16 a) (< a 9007199254740992.0)) (and (< 1.1102230246251565e-16 b) (< b 9007199254740992.0))) (and (< 1.1102230246251565e-16 c) (< c 9007199254740992.0)))
(/ (+ (- b) (sqrt (- (* b b) (* (* 3.0 a) c)))) (* 3.0 a)))