Cubic critical, wide range

Percentage Accurate: 17.8% → 99.4%
Time: 9.3s
Alternatives: 5
Speedup: 23.2×

Specification

?
\[\left(\left(4.930380657631324 \cdot 10^{-32} < a \land a < 2.028240960365167 \cdot 10^{+31}\right) \land \left(4.930380657631324 \cdot 10^{-32} < b \land b < 2.028240960365167 \cdot 10^{+31}\right)\right) \land \left(4.930380657631324 \cdot 10^{-32} < c \land c < 2.028240960365167 \cdot 10^{+31}\right)\]
\[\begin{array}{l} \\ \frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \end{array} \]
(FPCore (a b c)
 :precision binary64
 (/ (+ (- 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:

Local Percentage Accuracy vs ?

The average percentage accuracy by input value. Horizontal axis shows value of an input variable; the variable is choosen in the title. Vertical axis is accuracy; higher is better. Red represent the original program, while blue represents Herbie's suggestion. These can be toggled with buttons below the plot. The line is an average while dots represent individual samples.

Accuracy vs Speed?

Herbie found 5 alternatives:

AlternativeAccuracySpeedup
The accuracy (vertical axis) and speed (horizontal axis) of each alternatives. Up and to the right is better. The red square shows the initial program, and each blue circle shows an alternative.The line shows the best available speed-accuracy tradeoffs.

Initial Program: 17.8% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \end{array} \]
(FPCore (a b c)
 :precision binary64
 (/ (+ (- 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}

Alternative 1: 99.4% accurate, 0.2× speedup?

\[\begin{array}{l} \\ \frac{\frac{c \cdot \left(a \cdot {27}^{0.3333333333333333}\right) + \left({b}^{2} - {b}^{2}\right)}{-\left(b + \sqrt{{b}^{2} - 3 \cdot \left(c \cdot a\right)}\right)}}{a \cdot 3} \end{array} \]
(FPCore (a b c)
 :precision binary64
 (/
  (/
   (+ (* c (* a (pow 27.0 0.3333333333333333))) (- (pow b 2.0) (pow b 2.0)))
   (- (+ b (sqrt (- (pow b 2.0) (* 3.0 (* c a)))))))
  (* a 3.0)))
double code(double a, double b, double c) {
	return (((c * (a * pow(27.0, 0.3333333333333333))) + (pow(b, 2.0) - pow(b, 2.0))) / -(b + sqrt((pow(b, 2.0) - (3.0 * (c * a)))))) / (a * 3.0);
}
real(8) function code(a, b, c)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    real(8), intent (in) :: c
    code = (((c * (a * (27.0d0 ** 0.3333333333333333d0))) + ((b ** 2.0d0) - (b ** 2.0d0))) / -(b + sqrt(((b ** 2.0d0) - (3.0d0 * (c * a)))))) / (a * 3.0d0)
end function
public static double code(double a, double b, double c) {
	return (((c * (a * Math.pow(27.0, 0.3333333333333333))) + (Math.pow(b, 2.0) - Math.pow(b, 2.0))) / -(b + Math.sqrt((Math.pow(b, 2.0) - (3.0 * (c * a)))))) / (a * 3.0);
}
def code(a, b, c):
	return (((c * (a * math.pow(27.0, 0.3333333333333333))) + (math.pow(b, 2.0) - math.pow(b, 2.0))) / -(b + math.sqrt((math.pow(b, 2.0) - (3.0 * (c * a)))))) / (a * 3.0)
function code(a, b, c)
	return Float64(Float64(Float64(Float64(c * Float64(a * (27.0 ^ 0.3333333333333333))) + Float64((b ^ 2.0) - (b ^ 2.0))) / Float64(-Float64(b + sqrt(Float64((b ^ 2.0) - Float64(3.0 * Float64(c * a))))))) / Float64(a * 3.0))
end
function tmp = code(a, b, c)
	tmp = (((c * (a * (27.0 ^ 0.3333333333333333))) + ((b ^ 2.0) - (b ^ 2.0))) / -(b + sqrt(((b ^ 2.0) - (3.0 * (c * a)))))) / (a * 3.0);
end
code[a_, b_, c_] := N[(N[(N[(N[(c * N[(a * N[Power[27.0, 0.3333333333333333], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(N[Power[b, 2.0], $MachinePrecision] - N[Power[b, 2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / (-N[(b + N[Sqrt[N[(N[Power[b, 2.0], $MachinePrecision] - N[(3.0 * N[(c * a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision])), $MachinePrecision] / N[(a * 3.0), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{\frac{c \cdot \left(a \cdot {27}^{0.3333333333333333}\right) + \left({b}^{2} - {b}^{2}\right)}{-\left(b + \sqrt{{b}^{2} - 3 \cdot \left(c \cdot a\right)}\right)}}{a \cdot 3}
\end{array}
Derivation
  1. Initial program 16.5%

    \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]
  2. Step-by-step derivation
    1. add-cbrt-cube16.5%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - \color{blue}{\sqrt[3]{\left(\left(\left(3 \cdot a\right) \cdot c\right) \cdot \left(\left(3 \cdot a\right) \cdot c\right)\right) \cdot \left(\left(3 \cdot a\right) \cdot c\right)}}}}{3 \cdot a} \]
    2. pow1/316.4%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - \color{blue}{{\left(\left(\left(\left(3 \cdot a\right) \cdot c\right) \cdot \left(\left(3 \cdot a\right) \cdot c\right)\right) \cdot \left(\left(3 \cdot a\right) \cdot c\right)\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    3. pow316.4%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - {\color{blue}{\left({\left(\left(3 \cdot a\right) \cdot c\right)}^{3}\right)}}^{0.3333333333333333}}}{3 \cdot a} \]
    4. associate-*l*16.4%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - {\left({\color{blue}{\left(3 \cdot \left(a \cdot c\right)\right)}}^{3}\right)}^{0.3333333333333333}}}{3 \cdot a} \]
    5. unpow-prod-down16.4%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - {\color{blue}{\left({3}^{3} \cdot {\left(a \cdot c\right)}^{3}\right)}}^{0.3333333333333333}}}{3 \cdot a} \]
    6. metadata-eval16.4%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - {\left(\color{blue}{27} \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}{3 \cdot a} \]
  3. Applied egg-rr16.4%

    \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - \color{blue}{{\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
  4. Step-by-step derivation
    1. flip-+16.5%

      \[\leadsto \frac{\color{blue}{\frac{\left(-b\right) \cdot \left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}} \cdot \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}}{3 \cdot a} \]
    2. pow216.5%

      \[\leadsto \frac{\frac{\color{blue}{{\left(-b\right)}^{2}} - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}} \cdot \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    3. add-sqr-sqrt17.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \color{blue}{\left(b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}\right)}}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    4. pow217.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left(\color{blue}{{b}^{2}} - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    5. unpow1/317.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \color{blue}{\sqrt[3]{27 \cdot {\left(a \cdot c\right)}^{3}}}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    6. *-commutative17.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \sqrt[3]{\color{blue}{{\left(a \cdot c\right)}^{3} \cdot 27}}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    7. cbrt-prod17.1%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \color{blue}{\sqrt[3]{{\left(a \cdot c\right)}^{3}} \cdot \sqrt[3]{27}}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    8. unpow317.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \sqrt[3]{\color{blue}{\left(\left(a \cdot c\right) \cdot \left(a \cdot c\right)\right) \cdot \left(a \cdot c\right)}} \cdot \sqrt[3]{27}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    9. add-cbrt-cube17.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \color{blue}{\left(a \cdot c\right)} \cdot \sqrt[3]{27}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
  5. Applied egg-rr17.1%

    \[\leadsto \frac{\color{blue}{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}}{3 \cdot a} \]
  6. Step-by-step derivation
    1. associate--r-98.6%

      \[\leadsto \frac{\frac{\color{blue}{\left({\left(-b\right)}^{2} - {b}^{2}\right) + \left(a \cdot c\right) \cdot \sqrt[3]{27}}}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    2. +-commutative98.6%

      \[\leadsto \frac{\frac{\color{blue}{\left(a \cdot c\right) \cdot \sqrt[3]{27} + \left({\left(-b\right)}^{2} - {b}^{2}\right)}}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    3. *-commutative98.6%

      \[\leadsto \frac{\frac{\color{blue}{\left(c \cdot a\right)} \cdot \sqrt[3]{27} + \left({\left(-b\right)}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    4. associate-*l*98.6%

      \[\leadsto \frac{\frac{\color{blue}{c \cdot \left(a \cdot \sqrt[3]{27}\right)} + \left({\left(-b\right)}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    5. unpow298.6%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left(\color{blue}{\left(-b\right) \cdot \left(-b\right)} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    6. sqr-neg98.6%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left(\color{blue}{b \cdot b} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    7. unpow298.6%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left(\color{blue}{{b}^{2}} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    8. *-commutative98.6%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \color{blue}{\left(c \cdot a\right)} \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    9. associate-*l*98.6%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \color{blue}{c \cdot \left(a \cdot \sqrt[3]{27}\right)}}}}{3 \cdot a} \]
  7. Simplified98.6%

    \[\leadsto \frac{\color{blue}{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(a \cdot \sqrt[3]{27}\right)}}}}{3 \cdot a} \]
  8. Step-by-step derivation
    1. pow1/399.3%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \color{blue}{{27}^{0.3333333333333333}}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(a \cdot \sqrt[3]{27}\right)}}}{3 \cdot a} \]
  9. Applied egg-rr99.3%

    \[\leadsto \frac{\frac{c \cdot \left(a \cdot \color{blue}{{27}^{0.3333333333333333}}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(a \cdot \sqrt[3]{27}\right)}}}{3 \cdot a} \]
  10. Taylor expanded in c around 0 99.3%

    \[\leadsto \frac{\frac{c \cdot \left(a \cdot {27}^{0.3333333333333333}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \color{blue}{3 \cdot \left(a \cdot c\right)}}}}{3 \cdot a} \]
  11. Step-by-step derivation
    1. *-commutative99.3%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot {27}^{0.3333333333333333}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - 3 \cdot \color{blue}{\left(c \cdot a\right)}}}}{3 \cdot a} \]
  12. Simplified99.3%

    \[\leadsto \frac{\frac{c \cdot \left(a \cdot {27}^{0.3333333333333333}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \color{blue}{3 \cdot \left(c \cdot a\right)}}}}{3 \cdot a} \]
  13. Final simplification99.3%

    \[\leadsto \frac{\frac{c \cdot \left(a \cdot {27}^{0.3333333333333333}\right) + \left({b}^{2} - {b}^{2}\right)}{-\left(b + \sqrt{{b}^{2} - 3 \cdot \left(c \cdot a\right)}\right)}}{a \cdot 3} \]

Alternative 2: 99.2% accurate, 0.2× speedup?

\[\begin{array}{l} \\ \frac{\frac{\left({b}^{2} - {b}^{2}\right) + 3 \cdot \left(c \cdot a\right)}{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(a \cdot \sqrt[3]{27}\right)}}}{a \cdot 3} \end{array} \]
(FPCore (a b c)
 :precision binary64
 (/
  (/
   (+ (- (pow b 2.0) (pow b 2.0)) (* 3.0 (* c a)))
   (- (- b) (sqrt (- (pow b 2.0) (* c (* a (cbrt 27.0)))))))
  (* a 3.0)))
double code(double a, double b, double c) {
	return (((pow(b, 2.0) - pow(b, 2.0)) + (3.0 * (c * a))) / (-b - sqrt((pow(b, 2.0) - (c * (a * cbrt(27.0))))))) / (a * 3.0);
}
public static double code(double a, double b, double c) {
	return (((Math.pow(b, 2.0) - Math.pow(b, 2.0)) + (3.0 * (c * a))) / (-b - Math.sqrt((Math.pow(b, 2.0) - (c * (a * Math.cbrt(27.0))))))) / (a * 3.0);
}
function code(a, b, c)
	return Float64(Float64(Float64(Float64((b ^ 2.0) - (b ^ 2.0)) + Float64(3.0 * Float64(c * a))) / Float64(Float64(-b) - sqrt(Float64((b ^ 2.0) - Float64(c * Float64(a * cbrt(27.0))))))) / Float64(a * 3.0))
end
code[a_, b_, c_] := N[(N[(N[(N[(N[Power[b, 2.0], $MachinePrecision] - N[Power[b, 2.0], $MachinePrecision]), $MachinePrecision] + N[(3.0 * N[(c * a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[((-b) - N[Sqrt[N[(N[Power[b, 2.0], $MachinePrecision] - N[(c * N[(a * N[Power[27.0, 1/3], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(a * 3.0), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{\frac{\left({b}^{2} - {b}^{2}\right) + 3 \cdot \left(c \cdot a\right)}{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(a \cdot \sqrt[3]{27}\right)}}}{a \cdot 3}
\end{array}
Derivation
  1. Initial program 16.5%

    \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]
  2. Step-by-step derivation
    1. add-cbrt-cube16.5%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - \color{blue}{\sqrt[3]{\left(\left(\left(3 \cdot a\right) \cdot c\right) \cdot \left(\left(3 \cdot a\right) \cdot c\right)\right) \cdot \left(\left(3 \cdot a\right) \cdot c\right)}}}}{3 \cdot a} \]
    2. pow1/316.4%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - \color{blue}{{\left(\left(\left(\left(3 \cdot a\right) \cdot c\right) \cdot \left(\left(3 \cdot a\right) \cdot c\right)\right) \cdot \left(\left(3 \cdot a\right) \cdot c\right)\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    3. pow316.4%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - {\color{blue}{\left({\left(\left(3 \cdot a\right) \cdot c\right)}^{3}\right)}}^{0.3333333333333333}}}{3 \cdot a} \]
    4. associate-*l*16.4%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - {\left({\color{blue}{\left(3 \cdot \left(a \cdot c\right)\right)}}^{3}\right)}^{0.3333333333333333}}}{3 \cdot a} \]
    5. unpow-prod-down16.4%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - {\color{blue}{\left({3}^{3} \cdot {\left(a \cdot c\right)}^{3}\right)}}^{0.3333333333333333}}}{3 \cdot a} \]
    6. metadata-eval16.4%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - {\left(\color{blue}{27} \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}{3 \cdot a} \]
  3. Applied egg-rr16.4%

    \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - \color{blue}{{\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
  4. Step-by-step derivation
    1. flip-+16.5%

      \[\leadsto \frac{\color{blue}{\frac{\left(-b\right) \cdot \left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}} \cdot \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}}{3 \cdot a} \]
    2. pow216.5%

      \[\leadsto \frac{\frac{\color{blue}{{\left(-b\right)}^{2}} - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}} \cdot \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    3. add-sqr-sqrt17.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \color{blue}{\left(b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}\right)}}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    4. pow217.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left(\color{blue}{{b}^{2}} - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    5. unpow1/317.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \color{blue}{\sqrt[3]{27 \cdot {\left(a \cdot c\right)}^{3}}}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    6. *-commutative17.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \sqrt[3]{\color{blue}{{\left(a \cdot c\right)}^{3} \cdot 27}}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    7. cbrt-prod17.1%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \color{blue}{\sqrt[3]{{\left(a \cdot c\right)}^{3}} \cdot \sqrt[3]{27}}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    8. unpow317.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \sqrt[3]{\color{blue}{\left(\left(a \cdot c\right) \cdot \left(a \cdot c\right)\right) \cdot \left(a \cdot c\right)}} \cdot \sqrt[3]{27}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    9. add-cbrt-cube17.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \color{blue}{\left(a \cdot c\right)} \cdot \sqrt[3]{27}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
  5. Applied egg-rr17.1%

    \[\leadsto \frac{\color{blue}{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}}{3 \cdot a} \]
  6. Step-by-step derivation
    1. associate--r-98.6%

      \[\leadsto \frac{\frac{\color{blue}{\left({\left(-b\right)}^{2} - {b}^{2}\right) + \left(a \cdot c\right) \cdot \sqrt[3]{27}}}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    2. +-commutative98.6%

      \[\leadsto \frac{\frac{\color{blue}{\left(a \cdot c\right) \cdot \sqrt[3]{27} + \left({\left(-b\right)}^{2} - {b}^{2}\right)}}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    3. *-commutative98.6%

      \[\leadsto \frac{\frac{\color{blue}{\left(c \cdot a\right)} \cdot \sqrt[3]{27} + \left({\left(-b\right)}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    4. associate-*l*98.6%

      \[\leadsto \frac{\frac{\color{blue}{c \cdot \left(a \cdot \sqrt[3]{27}\right)} + \left({\left(-b\right)}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    5. unpow298.6%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left(\color{blue}{\left(-b\right) \cdot \left(-b\right)} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    6. sqr-neg98.6%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left(\color{blue}{b \cdot b} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    7. unpow298.6%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left(\color{blue}{{b}^{2}} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    8. *-commutative98.6%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \color{blue}{\left(c \cdot a\right)} \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    9. associate-*l*98.6%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \color{blue}{c \cdot \left(a \cdot \sqrt[3]{27}\right)}}}}{3 \cdot a} \]
  7. Simplified98.6%

    \[\leadsto \frac{\color{blue}{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(a \cdot \sqrt[3]{27}\right)}}}}{3 \cdot a} \]
  8. Taylor expanded in c around 0 99.2%

    \[\leadsto \frac{\frac{\color{blue}{3 \cdot \left(a \cdot c\right)} + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(a \cdot \sqrt[3]{27}\right)}}}{3 \cdot a} \]
  9. Step-by-step derivation
    1. *-commutative99.3%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot {27}^{0.3333333333333333}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - 3 \cdot \color{blue}{\left(c \cdot a\right)}}}}{3 \cdot a} \]
  10. Simplified99.2%

    \[\leadsto \frac{\frac{\color{blue}{3 \cdot \left(c \cdot a\right)} + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(a \cdot \sqrt[3]{27}\right)}}}{3 \cdot a} \]
  11. Final simplification99.2%

    \[\leadsto \frac{\frac{\left({b}^{2} - {b}^{2}\right) + 3 \cdot \left(c \cdot a\right)}{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(a \cdot \sqrt[3]{27}\right)}}}{a \cdot 3} \]

Alternative 3: 98.9% accurate, 0.3× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := c \cdot \left(a \cdot \sqrt[3]{27}\right)\\ \frac{t_0}{\frac{\left(-b\right) - \sqrt{{b}^{2} - t_0}}{\frac{0.3333333333333333}{a}}} \end{array} \end{array} \]
(FPCore (a b c)
 :precision binary64
 (let* ((t_0 (* c (* a (cbrt 27.0)))))
   (/ t_0 (/ (- (- b) (sqrt (- (pow b 2.0) t_0))) (/ 0.3333333333333333 a)))))
double code(double a, double b, double c) {
	double t_0 = c * (a * cbrt(27.0));
	return t_0 / ((-b - sqrt((pow(b, 2.0) - t_0))) / (0.3333333333333333 / a));
}
public static double code(double a, double b, double c) {
	double t_0 = c * (a * Math.cbrt(27.0));
	return t_0 / ((-b - Math.sqrt((Math.pow(b, 2.0) - t_0))) / (0.3333333333333333 / a));
}
function code(a, b, c)
	t_0 = Float64(c * Float64(a * cbrt(27.0)))
	return Float64(t_0 / Float64(Float64(Float64(-b) - sqrt(Float64((b ^ 2.0) - t_0))) / Float64(0.3333333333333333 / a)))
end
code[a_, b_, c_] := Block[{t$95$0 = N[(c * N[(a * N[Power[27.0, 1/3], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]}, N[(t$95$0 / N[(N[((-b) - N[Sqrt[N[(N[Power[b, 2.0], $MachinePrecision] - t$95$0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(0.3333333333333333 / a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := c \cdot \left(a \cdot \sqrt[3]{27}\right)\\
\frac{t_0}{\frac{\left(-b\right) - \sqrt{{b}^{2} - t_0}}{\frac{0.3333333333333333}{a}}}
\end{array}
\end{array}
Derivation
  1. Initial program 16.5%

    \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]
  2. Step-by-step derivation
    1. add-cbrt-cube16.5%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - \color{blue}{\sqrt[3]{\left(\left(\left(3 \cdot a\right) \cdot c\right) \cdot \left(\left(3 \cdot a\right) \cdot c\right)\right) \cdot \left(\left(3 \cdot a\right) \cdot c\right)}}}}{3 \cdot a} \]
    2. pow1/316.4%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - \color{blue}{{\left(\left(\left(\left(3 \cdot a\right) \cdot c\right) \cdot \left(\left(3 \cdot a\right) \cdot c\right)\right) \cdot \left(\left(3 \cdot a\right) \cdot c\right)\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    3. pow316.4%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - {\color{blue}{\left({\left(\left(3 \cdot a\right) \cdot c\right)}^{3}\right)}}^{0.3333333333333333}}}{3 \cdot a} \]
    4. associate-*l*16.4%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - {\left({\color{blue}{\left(3 \cdot \left(a \cdot c\right)\right)}}^{3}\right)}^{0.3333333333333333}}}{3 \cdot a} \]
    5. unpow-prod-down16.4%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - {\color{blue}{\left({3}^{3} \cdot {\left(a \cdot c\right)}^{3}\right)}}^{0.3333333333333333}}}{3 \cdot a} \]
    6. metadata-eval16.4%

      \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - {\left(\color{blue}{27} \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}{3 \cdot a} \]
  3. Applied egg-rr16.4%

    \[\leadsto \frac{\left(-b\right) + \sqrt{b \cdot b - \color{blue}{{\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
  4. Step-by-step derivation
    1. flip-+16.5%

      \[\leadsto \frac{\color{blue}{\frac{\left(-b\right) \cdot \left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}} \cdot \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}}{3 \cdot a} \]
    2. pow216.5%

      \[\leadsto \frac{\frac{\color{blue}{{\left(-b\right)}^{2}} - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}} \cdot \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    3. add-sqr-sqrt17.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \color{blue}{\left(b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}\right)}}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    4. pow217.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left(\color{blue}{{b}^{2}} - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    5. unpow1/317.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \color{blue}{\sqrt[3]{27 \cdot {\left(a \cdot c\right)}^{3}}}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    6. *-commutative17.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \sqrt[3]{\color{blue}{{\left(a \cdot c\right)}^{3} \cdot 27}}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    7. cbrt-prod17.1%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \color{blue}{\sqrt[3]{{\left(a \cdot c\right)}^{3}} \cdot \sqrt[3]{27}}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    8. unpow317.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \sqrt[3]{\color{blue}{\left(\left(a \cdot c\right) \cdot \left(a \cdot c\right)\right) \cdot \left(a \cdot c\right)}} \cdot \sqrt[3]{27}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
    9. add-cbrt-cube17.0%

      \[\leadsto \frac{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \color{blue}{\left(a \cdot c\right)} \cdot \sqrt[3]{27}\right)}{\left(-b\right) - \sqrt{b \cdot b - {\left(27 \cdot {\left(a \cdot c\right)}^{3}\right)}^{0.3333333333333333}}}}{3 \cdot a} \]
  5. Applied egg-rr17.1%

    \[\leadsto \frac{\color{blue}{\frac{{\left(-b\right)}^{2} - \left({b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}}{3 \cdot a} \]
  6. Step-by-step derivation
    1. associate--r-98.6%

      \[\leadsto \frac{\frac{\color{blue}{\left({\left(-b\right)}^{2} - {b}^{2}\right) + \left(a \cdot c\right) \cdot \sqrt[3]{27}}}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    2. +-commutative98.6%

      \[\leadsto \frac{\frac{\color{blue}{\left(a \cdot c\right) \cdot \sqrt[3]{27} + \left({\left(-b\right)}^{2} - {b}^{2}\right)}}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    3. *-commutative98.6%

      \[\leadsto \frac{\frac{\color{blue}{\left(c \cdot a\right)} \cdot \sqrt[3]{27} + \left({\left(-b\right)}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    4. associate-*l*98.6%

      \[\leadsto \frac{\frac{\color{blue}{c \cdot \left(a \cdot \sqrt[3]{27}\right)} + \left({\left(-b\right)}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    5. unpow298.6%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left(\color{blue}{\left(-b\right) \cdot \left(-b\right)} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    6. sqr-neg98.6%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left(\color{blue}{b \cdot b} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    7. unpow298.6%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left(\color{blue}{{b}^{2}} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \left(a \cdot c\right) \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    8. *-commutative98.6%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \color{blue}{\left(c \cdot a\right)} \cdot \sqrt[3]{27}}}}{3 \cdot a} \]
    9. associate-*l*98.6%

      \[\leadsto \frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - \color{blue}{c \cdot \left(a \cdot \sqrt[3]{27}\right)}}}}{3 \cdot a} \]
  7. Simplified98.6%

    \[\leadsto \frac{\color{blue}{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(a \cdot \sqrt[3]{27}\right)}}}}{3 \cdot a} \]
  8. Step-by-step derivation
    1. expm1-log1p-u83.9%

      \[\leadsto \color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(\frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(a \cdot \sqrt[3]{27}\right)}}}{3 \cdot a}\right)\right)} \]
    2. expm1-udef19.9%

      \[\leadsto \color{blue}{e^{\mathsf{log1p}\left(\frac{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right) + \left({b}^{2} - {b}^{2}\right)}{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(a \cdot \sqrt[3]{27}\right)}}}{3 \cdot a}\right)} - 1} \]
  9. Applied egg-rr19.9%

    \[\leadsto \color{blue}{e^{\mathsf{log1p}\left(\frac{\mathsf{fma}\left(c, \sqrt[3]{27} \cdot a, 0\right)}{\left(a \cdot 3\right) \cdot \left(\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(\sqrt[3]{27} \cdot a\right)}\right)}\right)} - 1} \]
  10. Step-by-step derivation
    1. expm1-def83.9%

      \[\leadsto \color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(\frac{\mathsf{fma}\left(c, \sqrt[3]{27} \cdot a, 0\right)}{\left(a \cdot 3\right) \cdot \left(\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(\sqrt[3]{27} \cdot a\right)}\right)}\right)\right)} \]
    2. expm1-log1p98.5%

      \[\leadsto \color{blue}{\frac{\mathsf{fma}\left(c, \sqrt[3]{27} \cdot a, 0\right)}{\left(a \cdot 3\right) \cdot \left(\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(\sqrt[3]{27} \cdot a\right)}\right)}} \]
    3. associate-/r*98.6%

      \[\leadsto \color{blue}{\frac{\frac{\mathsf{fma}\left(c, \sqrt[3]{27} \cdot a, 0\right)}{a \cdot 3}}{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(\sqrt[3]{27} \cdot a\right)}}} \]
    4. *-rgt-identity98.6%

      \[\leadsto \frac{\frac{\color{blue}{\mathsf{fma}\left(c, \sqrt[3]{27} \cdot a, 0\right) \cdot 1}}{a \cdot 3}}{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(\sqrt[3]{27} \cdot a\right)}} \]
    5. associate-*r/98.6%

      \[\leadsto \frac{\color{blue}{\mathsf{fma}\left(c, \sqrt[3]{27} \cdot a, 0\right) \cdot \frac{1}{a \cdot 3}}}{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(\sqrt[3]{27} \cdot a\right)}} \]
    6. associate-/l*98.6%

      \[\leadsto \color{blue}{\frac{\mathsf{fma}\left(c, \sqrt[3]{27} \cdot a, 0\right)}{\frac{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(\sqrt[3]{27} \cdot a\right)}}{\frac{1}{a \cdot 3}}}} \]
    7. fma-udef98.6%

      \[\leadsto \frac{\color{blue}{c \cdot \left(\sqrt[3]{27} \cdot a\right) + 0}}{\frac{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(\sqrt[3]{27} \cdot a\right)}}{\frac{1}{a \cdot 3}}} \]
    8. +-rgt-identity98.6%

      \[\leadsto \frac{\color{blue}{c \cdot \left(\sqrt[3]{27} \cdot a\right)}}{\frac{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(\sqrt[3]{27} \cdot a\right)}}{\frac{1}{a \cdot 3}}} \]
    9. *-commutative98.6%

      \[\leadsto \frac{c \cdot \color{blue}{\left(a \cdot \sqrt[3]{27}\right)}}{\frac{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(\sqrt[3]{27} \cdot a\right)}}{\frac{1}{a \cdot 3}}} \]
  11. Simplified99.0%

    \[\leadsto \color{blue}{\frac{c \cdot \left(a \cdot \sqrt[3]{27}\right)}{\frac{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(a \cdot \sqrt[3]{27}\right)}}{\frac{0.3333333333333333}{a}}}} \]
  12. Final simplification99.0%

    \[\leadsto \frac{c \cdot \left(a \cdot \sqrt[3]{27}\right)}{\frac{\left(-b\right) - \sqrt{{b}^{2} - c \cdot \left(a \cdot \sqrt[3]{27}\right)}}{\frac{0.3333333333333333}{a}}} \]

Alternative 4: 95.2% accurate, 0.5× speedup?

\[\begin{array}{l} \\ -0.5 \cdot \frac{c}{b} + -0.375 \cdot \frac{a \cdot {c}^{2}}{{b}^{3}} \end{array} \]
(FPCore (a b c)
 :precision binary64
 (+ (* -0.5 (/ c b)) (* -0.375 (/ (* a (pow c 2.0)) (pow b 3.0)))))
double code(double a, double b, double c) {
	return (-0.5 * (c / b)) + (-0.375 * ((a * pow(c, 2.0)) / pow(b, 3.0)));
}
real(8) function code(a, b, c)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    real(8), intent (in) :: c
    code = ((-0.5d0) * (c / b)) + ((-0.375d0) * ((a * (c ** 2.0d0)) / (b ** 3.0d0)))
end function
public static double code(double a, double b, double c) {
	return (-0.5 * (c / b)) + (-0.375 * ((a * Math.pow(c, 2.0)) / Math.pow(b, 3.0)));
}
def code(a, b, c):
	return (-0.5 * (c / b)) + (-0.375 * ((a * math.pow(c, 2.0)) / math.pow(b, 3.0)))
function code(a, b, c)
	return Float64(Float64(-0.5 * Float64(c / b)) + Float64(-0.375 * Float64(Float64(a * (c ^ 2.0)) / (b ^ 3.0))))
end
function tmp = code(a, b, c)
	tmp = (-0.5 * (c / b)) + (-0.375 * ((a * (c ^ 2.0)) / (b ^ 3.0)));
end
code[a_, b_, c_] := N[(N[(-0.5 * N[(c / b), $MachinePrecision]), $MachinePrecision] + N[(-0.375 * N[(N[(a * N[Power[c, 2.0], $MachinePrecision]), $MachinePrecision] / N[Power[b, 3.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
-0.5 \cdot \frac{c}{b} + -0.375 \cdot \frac{a \cdot {c}^{2}}{{b}^{3}}
\end{array}
Derivation
  1. Initial program 16.5%

    \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]
  2. Taylor expanded in b around inf 96.3%

    \[\leadsto \color{blue}{-0.5 \cdot \frac{c}{b} + -0.375 \cdot \frac{a \cdot {c}^{2}}{{b}^{3}}} \]
  3. Final simplification96.3%

    \[\leadsto -0.5 \cdot \frac{c}{b} + -0.375 \cdot \frac{a \cdot {c}^{2}}{{b}^{3}} \]

Alternative 5: 90.4% accurate, 23.2× speedup?

\[\begin{array}{l} \\ \frac{c \cdot -0.5}{b} \end{array} \]
(FPCore (a b c) :precision binary64 (/ (* c -0.5) b))
double code(double a, double b, double c) {
	return (c * -0.5) / b;
}
real(8) function code(a, b, c)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    real(8), intent (in) :: c
    code = (c * (-0.5d0)) / b
end function
public static double code(double a, double b, double c) {
	return (c * -0.5) / b;
}
def code(a, b, c):
	return (c * -0.5) / b
function code(a, b, c)
	return Float64(Float64(c * -0.5) / b)
end
function tmp = code(a, b, c)
	tmp = (c * -0.5) / b;
end
code[a_, b_, c_] := N[(N[(c * -0.5), $MachinePrecision] / b), $MachinePrecision]
\begin{array}{l}

\\
\frac{c \cdot -0.5}{b}
\end{array}
Derivation
  1. Initial program 16.5%

    \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]
  2. Taylor expanded in b around inf 91.5%

    \[\leadsto \color{blue}{-0.5 \cdot \frac{c}{b}} \]
  3. Step-by-step derivation
    1. *-commutative91.5%

      \[\leadsto \color{blue}{\frac{c}{b} \cdot -0.5} \]
    2. associate-*l/91.5%

      \[\leadsto \color{blue}{\frac{c \cdot -0.5}{b}} \]
  4. Simplified91.5%

    \[\leadsto \color{blue}{\frac{c \cdot -0.5}{b}} \]
  5. Final simplification91.5%

    \[\leadsto \frac{c \cdot -0.5}{b} \]

Reproduce

?
herbie shell --seed 2023301 
(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)))