Cubic critical, narrow range

Percentage Accurate: 54.8% → 99.6%
Time: 12.8s
Alternatives: 5
Speedup: 2.9×

Specification

?
\[\left(\left(1.0536712127723509 \cdot 10^{-8} < a \land a < 94906265.62425156\right) \land \left(1.0536712127723509 \cdot 10^{-8} < b \land b < 94906265.62425156\right)\right) \land \left(1.0536712127723509 \cdot 10^{-8} < c \land c < 94906265.62425156\right)\]
\[\begin{array}{l} \\ \frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \end{array} \]
(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: 54.8% 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: 99.6% accurate, 1.2× speedup?

\[\begin{array}{l} \\ \frac{-c}{\sqrt{\mathsf{fma}\left(b, b, \left(c \cdot -3\right) \cdot a\right)} + b} \end{array} \]
(FPCore (a b c)
 :precision binary64
 (/ (- c) (+ (sqrt (fma b b (* (* c -3.0) a))) b)))
double code(double a, double b, double c) {
	return -c / (sqrt(fma(b, b, ((c * -3.0) * a))) + b);
}
function code(a, b, c)
	return Float64(Float64(-c) / Float64(sqrt(fma(b, b, Float64(Float64(c * -3.0) * a))) + b))
end
code[a_, b_, c_] := N[((-c) / N[(N[Sqrt[N[(b * b + N[(N[(c * -3.0), $MachinePrecision] * a), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] + b), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{-c}{\sqrt{\mathsf{fma}\left(b, b, \left(c \cdot -3\right) \cdot a\right)} + b}
\end{array}
Derivation
  1. Initial program 53.7%

    \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}} \]
    2. clear-numN/A

      \[\leadsto \color{blue}{\frac{1}{\frac{3 \cdot a}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    3. lift-*.f64N/A

      \[\leadsto \frac{1}{\frac{\color{blue}{3 \cdot a}}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}} \]
    4. associate-/l*N/A

      \[\leadsto \frac{1}{\color{blue}{3 \cdot \frac{a}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    5. associate-/r*N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{3}}{\frac{a}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    6. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{3}}{\frac{a}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    7. metadata-evalN/A

      \[\leadsto \frac{\color{blue}{\frac{1}{3}}}{\frac{a}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}} \]
    8. lower-/.f6453.7

      \[\leadsto \frac{0.3333333333333333}{\color{blue}{\frac{a}{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    9. lift-+.f64N/A

      \[\leadsto \frac{\frac{1}{3}}{\frac{a}{\color{blue}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    10. +-commutativeN/A

      \[\leadsto \frac{\frac{1}{3}}{\frac{a}{\color{blue}{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c} + \left(\mathsf{neg}\left(b\right)\right)}}} \]
    11. lift-neg.f64N/A

      \[\leadsto \frac{\frac{1}{3}}{\frac{a}{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c} + \color{blue}{\left(\mathsf{neg}\left(b\right)\right)}}} \]
    12. unsub-negN/A

      \[\leadsto \frac{\frac{1}{3}}{\frac{a}{\color{blue}{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c} - b}}} \]
    13. lower--.f6453.7

      \[\leadsto \frac{0.3333333333333333}{\frac{a}{\color{blue}{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c} - b}}} \]
  4. Applied rewrites53.7%

    \[\leadsto \color{blue}{\frac{0.3333333333333333}{\frac{a}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b}}} \]
  5. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{3}}{\frac{a}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b}}} \]
    2. lift-/.f64N/A

      \[\leadsto \frac{\frac{1}{3}}{\color{blue}{\frac{a}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b}}} \]
    3. associate-/r/N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{3}}{a} \cdot \left(\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b\right)} \]
    4. lift--.f64N/A

      \[\leadsto \frac{\frac{1}{3}}{a} \cdot \color{blue}{\left(\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b\right)} \]
    5. flip--N/A

      \[\leadsto \frac{\frac{1}{3}}{a} \cdot \color{blue}{\frac{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b \cdot b}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b}} \]
    6. associate-*r/N/A

      \[\leadsto \color{blue}{\frac{\frac{\frac{1}{3}}{a} \cdot \left(\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b \cdot b\right)}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b}} \]
    7. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{\frac{1}{3}}{a} \cdot \left(\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b \cdot b\right)}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b}} \]
  6. Applied rewrites54.9%

    \[\leadsto \color{blue}{\frac{\frac{0.3333333333333333}{a} \cdot \left(\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right) - b \cdot b\right)}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b}} \]
  7. Taylor expanded in c around 0

    \[\leadsto \frac{\color{blue}{-1 \cdot c}}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b} \]
  8. Step-by-step derivation
    1. mul-1-negN/A

      \[\leadsto \frac{\color{blue}{\mathsf{neg}\left(c\right)}}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b} \]
    2. lower-neg.f6499.5

      \[\leadsto \frac{\color{blue}{-c}}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b} \]
  9. Applied rewrites99.5%

    \[\leadsto \frac{\color{blue}{-c}}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b} \]
  10. Step-by-step derivation
    1. lift-*.f64N/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, \color{blue}{b \cdot b}\right)} + b} \]
    2. lift-fma.f64N/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\sqrt{\color{blue}{\left(-3 \cdot c\right) \cdot a + b \cdot b}} + b} \]
    3. +-commutativeN/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\sqrt{\color{blue}{b \cdot b + \left(-3 \cdot c\right) \cdot a}} + b} \]
    4. lower-fma.f64N/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\sqrt{\color{blue}{\mathsf{fma}\left(b, b, \left(-3 \cdot c\right) \cdot a\right)}} + b} \]
    5. lower-*.f6499.5

      \[\leadsto \frac{-c}{\sqrt{\mathsf{fma}\left(b, b, \color{blue}{\left(-3 \cdot c\right) \cdot a}\right)} + b} \]
    6. lift-*.f64N/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\sqrt{\mathsf{fma}\left(b, b, \color{blue}{\left(-3 \cdot c\right)} \cdot a\right)} + b} \]
    7. *-commutativeN/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\sqrt{\mathsf{fma}\left(b, b, \color{blue}{\left(c \cdot -3\right)} \cdot a\right)} + b} \]
    8. lower-*.f6499.5

      \[\leadsto \frac{-c}{\sqrt{\mathsf{fma}\left(b, b, \color{blue}{\left(c \cdot -3\right)} \cdot a\right)} + b} \]
  11. Applied rewrites99.5%

    \[\leadsto \frac{-c}{\sqrt{\color{blue}{\mathsf{fma}\left(b, b, \left(c \cdot -3\right) \cdot a\right)}} + b} \]
  12. Add Preprocessing

Alternative 2: 82.7% accurate, 1.2× speedup?

\[\begin{array}{l} \\ \frac{-c}{\mathsf{fma}\left(\frac{c}{b} \cdot a, -1.5, 2 \cdot b\right)} \end{array} \]
(FPCore (a b c)
 :precision binary64
 (/ (- c) (fma (* (/ c b) a) -1.5 (* 2.0 b))))
double code(double a, double b, double c) {
	return -c / fma(((c / b) * a), -1.5, (2.0 * b));
}
function code(a, b, c)
	return Float64(Float64(-c) / fma(Float64(Float64(c / b) * a), -1.5, Float64(2.0 * b)))
end
code[a_, b_, c_] := N[((-c) / N[(N[(N[(c / b), $MachinePrecision] * a), $MachinePrecision] * -1.5 + N[(2.0 * b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{-c}{\mathsf{fma}\left(\frac{c}{b} \cdot a, -1.5, 2 \cdot b\right)}
\end{array}
Derivation
  1. Initial program 53.7%

    \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}} \]
    2. clear-numN/A

      \[\leadsto \color{blue}{\frac{1}{\frac{3 \cdot a}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    3. lift-*.f64N/A

      \[\leadsto \frac{1}{\frac{\color{blue}{3 \cdot a}}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}} \]
    4. associate-/l*N/A

      \[\leadsto \frac{1}{\color{blue}{3 \cdot \frac{a}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    5. associate-/r*N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{3}}{\frac{a}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    6. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{3}}{\frac{a}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    7. metadata-evalN/A

      \[\leadsto \frac{\color{blue}{\frac{1}{3}}}{\frac{a}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}} \]
    8. lower-/.f6453.7

      \[\leadsto \frac{0.3333333333333333}{\color{blue}{\frac{a}{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    9. lift-+.f64N/A

      \[\leadsto \frac{\frac{1}{3}}{\frac{a}{\color{blue}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    10. +-commutativeN/A

      \[\leadsto \frac{\frac{1}{3}}{\frac{a}{\color{blue}{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c} + \left(\mathsf{neg}\left(b\right)\right)}}} \]
    11. lift-neg.f64N/A

      \[\leadsto \frac{\frac{1}{3}}{\frac{a}{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c} + \color{blue}{\left(\mathsf{neg}\left(b\right)\right)}}} \]
    12. unsub-negN/A

      \[\leadsto \frac{\frac{1}{3}}{\frac{a}{\color{blue}{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c} - b}}} \]
    13. lower--.f6453.7

      \[\leadsto \frac{0.3333333333333333}{\frac{a}{\color{blue}{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c} - b}}} \]
  4. Applied rewrites53.7%

    \[\leadsto \color{blue}{\frac{0.3333333333333333}{\frac{a}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b}}} \]
  5. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{3}}{\frac{a}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b}}} \]
    2. lift-/.f64N/A

      \[\leadsto \frac{\frac{1}{3}}{\color{blue}{\frac{a}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b}}} \]
    3. associate-/r/N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{3}}{a} \cdot \left(\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b\right)} \]
    4. lift--.f64N/A

      \[\leadsto \frac{\frac{1}{3}}{a} \cdot \color{blue}{\left(\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b\right)} \]
    5. flip--N/A

      \[\leadsto \frac{\frac{1}{3}}{a} \cdot \color{blue}{\frac{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b \cdot b}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b}} \]
    6. associate-*r/N/A

      \[\leadsto \color{blue}{\frac{\frac{\frac{1}{3}}{a} \cdot \left(\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b \cdot b\right)}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b}} \]
    7. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{\frac{1}{3}}{a} \cdot \left(\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b \cdot b\right)}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b}} \]
  6. Applied rewrites54.9%

    \[\leadsto \color{blue}{\frac{\frac{0.3333333333333333}{a} \cdot \left(\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right) - b \cdot b\right)}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b}} \]
  7. Taylor expanded in c around 0

    \[\leadsto \frac{\color{blue}{-1 \cdot c}}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b} \]
  8. Step-by-step derivation
    1. mul-1-negN/A

      \[\leadsto \frac{\color{blue}{\mathsf{neg}\left(c\right)}}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b} \]
    2. lower-neg.f6499.5

      \[\leadsto \frac{\color{blue}{-c}}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b} \]
  9. Applied rewrites99.5%

    \[\leadsto \frac{\color{blue}{-c}}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b} \]
  10. Taylor expanded in c around 0

    \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\color{blue}{\frac{-3}{2} \cdot \frac{a \cdot c}{b} + 2 \cdot b}} \]
  11. Step-by-step derivation
    1. *-commutativeN/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\color{blue}{\frac{a \cdot c}{b} \cdot \frac{-3}{2}} + 2 \cdot b} \]
    2. lower-fma.f64N/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\color{blue}{\mathsf{fma}\left(\frac{a \cdot c}{b}, \frac{-3}{2}, 2 \cdot b\right)}} \]
    3. associate-/l*N/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\mathsf{fma}\left(\color{blue}{a \cdot \frac{c}{b}}, \frac{-3}{2}, 2 \cdot b\right)} \]
    4. lower-*.f64N/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\mathsf{fma}\left(\color{blue}{a \cdot \frac{c}{b}}, \frac{-3}{2}, 2 \cdot b\right)} \]
    5. lower-/.f64N/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\mathsf{fma}\left(a \cdot \color{blue}{\frac{c}{b}}, \frac{-3}{2}, 2 \cdot b\right)} \]
    6. lower-*.f6482.7

      \[\leadsto \frac{-c}{\mathsf{fma}\left(a \cdot \frac{c}{b}, -1.5, \color{blue}{2 \cdot b}\right)} \]
  12. Applied rewrites82.7%

    \[\leadsto \frac{-c}{\color{blue}{\mathsf{fma}\left(a \cdot \frac{c}{b}, -1.5, 2 \cdot b\right)}} \]
  13. Final simplification82.7%

    \[\leadsto \frac{-c}{\mathsf{fma}\left(\frac{c}{b} \cdot a, -1.5, 2 \cdot b\right)} \]
  14. Add Preprocessing

Alternative 3: 82.6% accurate, 1.3× speedup?

\[\begin{array}{l} \\ \frac{-c}{\mathsf{fma}\left(\frac{c}{b} \cdot a, -1.5, b\right) + b} \end{array} \]
(FPCore (a b c) :precision binary64 (/ (- c) (+ (fma (* (/ c b) a) -1.5 b) b)))
double code(double a, double b, double c) {
	return -c / (fma(((c / b) * a), -1.5, b) + b);
}
function code(a, b, c)
	return Float64(Float64(-c) / Float64(fma(Float64(Float64(c / b) * a), -1.5, b) + b))
end
code[a_, b_, c_] := N[((-c) / N[(N[(N[(N[(c / b), $MachinePrecision] * a), $MachinePrecision] * -1.5 + b), $MachinePrecision] + b), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{-c}{\mathsf{fma}\left(\frac{c}{b} \cdot a, -1.5, b\right) + b}
\end{array}
Derivation
  1. Initial program 53.7%

    \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}} \]
    2. clear-numN/A

      \[\leadsto \color{blue}{\frac{1}{\frac{3 \cdot a}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    3. lift-*.f64N/A

      \[\leadsto \frac{1}{\frac{\color{blue}{3 \cdot a}}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}} \]
    4. associate-/l*N/A

      \[\leadsto \frac{1}{\color{blue}{3 \cdot \frac{a}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    5. associate-/r*N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{3}}{\frac{a}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    6. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{3}}{\frac{a}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    7. metadata-evalN/A

      \[\leadsto \frac{\color{blue}{\frac{1}{3}}}{\frac{a}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}} \]
    8. lower-/.f6453.7

      \[\leadsto \frac{0.3333333333333333}{\color{blue}{\frac{a}{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    9. lift-+.f64N/A

      \[\leadsto \frac{\frac{1}{3}}{\frac{a}{\color{blue}{\left(\mathsf{neg}\left(b\right)\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}}} \]
    10. +-commutativeN/A

      \[\leadsto \frac{\frac{1}{3}}{\frac{a}{\color{blue}{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c} + \left(\mathsf{neg}\left(b\right)\right)}}} \]
    11. lift-neg.f64N/A

      \[\leadsto \frac{\frac{1}{3}}{\frac{a}{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c} + \color{blue}{\left(\mathsf{neg}\left(b\right)\right)}}} \]
    12. unsub-negN/A

      \[\leadsto \frac{\frac{1}{3}}{\frac{a}{\color{blue}{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c} - b}}} \]
    13. lower--.f6453.7

      \[\leadsto \frac{0.3333333333333333}{\frac{a}{\color{blue}{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c} - b}}} \]
  4. Applied rewrites53.7%

    \[\leadsto \color{blue}{\frac{0.3333333333333333}{\frac{a}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b}}} \]
  5. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{3}}{\frac{a}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b}}} \]
    2. lift-/.f64N/A

      \[\leadsto \frac{\frac{1}{3}}{\color{blue}{\frac{a}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b}}} \]
    3. associate-/r/N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{3}}{a} \cdot \left(\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b\right)} \]
    4. lift--.f64N/A

      \[\leadsto \frac{\frac{1}{3}}{a} \cdot \color{blue}{\left(\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b\right)} \]
    5. flip--N/A

      \[\leadsto \frac{\frac{1}{3}}{a} \cdot \color{blue}{\frac{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b \cdot b}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b}} \]
    6. associate-*r/N/A

      \[\leadsto \color{blue}{\frac{\frac{\frac{1}{3}}{a} \cdot \left(\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b \cdot b\right)}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b}} \]
    7. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{\frac{1}{3}}{a} \cdot \left(\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} - b \cdot b\right)}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b}} \]
  6. Applied rewrites54.9%

    \[\leadsto \color{blue}{\frac{\frac{0.3333333333333333}{a} \cdot \left(\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right) - b \cdot b\right)}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b}} \]
  7. Taylor expanded in c around 0

    \[\leadsto \frac{\color{blue}{-1 \cdot c}}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b} \]
  8. Step-by-step derivation
    1. mul-1-negN/A

      \[\leadsto \frac{\color{blue}{\mathsf{neg}\left(c\right)}}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b} \]
    2. lower-neg.f6499.5

      \[\leadsto \frac{\color{blue}{-c}}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b} \]
  9. Applied rewrites99.5%

    \[\leadsto \frac{\color{blue}{-c}}{\sqrt{\mathsf{fma}\left(-3 \cdot c, a, b \cdot b\right)} + b} \]
  10. Taylor expanded in c around 0

    \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\color{blue}{\left(b + \frac{-3}{2} \cdot \frac{a \cdot c}{b}\right)} + b} \]
  11. Step-by-step derivation
    1. +-commutativeN/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\color{blue}{\left(\frac{-3}{2} \cdot \frac{a \cdot c}{b} + b\right)} + b} \]
    2. *-commutativeN/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\left(\color{blue}{\frac{a \cdot c}{b} \cdot \frac{-3}{2}} + b\right) + b} \]
    3. lower-fma.f64N/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\color{blue}{\mathsf{fma}\left(\frac{a \cdot c}{b}, \frac{-3}{2}, b\right)} + b} \]
    4. associate-/l*N/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\mathsf{fma}\left(\color{blue}{a \cdot \frac{c}{b}}, \frac{-3}{2}, b\right) + b} \]
    5. lower-*.f64N/A

      \[\leadsto \frac{\mathsf{neg}\left(c\right)}{\mathsf{fma}\left(\color{blue}{a \cdot \frac{c}{b}}, \frac{-3}{2}, b\right) + b} \]
    6. lower-/.f6482.7

      \[\leadsto \frac{-c}{\mathsf{fma}\left(a \cdot \color{blue}{\frac{c}{b}}, -1.5, b\right) + b} \]
  12. Applied rewrites82.7%

    \[\leadsto \frac{-c}{\color{blue}{\mathsf{fma}\left(a \cdot \frac{c}{b}, -1.5, b\right)} + b} \]
  13. Final simplification82.7%

    \[\leadsto \frac{-c}{\mathsf{fma}\left(\frac{c}{b} \cdot a, -1.5, b\right) + b} \]
  14. Add Preprocessing

Alternative 4: 64.9% accurate, 2.9× speedup?

\[\begin{array}{l} \\ -0.5 \cdot \frac{c}{b} \end{array} \]
(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}
Derivation
  1. Initial program 53.7%

    \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]
  2. Add Preprocessing
  3. Taylor expanded in c around 0

    \[\leadsto \color{blue}{\frac{-1}{2} \cdot \frac{c}{b}} \]
  4. Step-by-step derivation
    1. *-commutativeN/A

      \[\leadsto \color{blue}{\frac{c}{b} \cdot \frac{-1}{2}} \]
    2. lower-*.f64N/A

      \[\leadsto \color{blue}{\frac{c}{b} \cdot \frac{-1}{2}} \]
    3. lower-/.f6465.9

      \[\leadsto \color{blue}{\frac{c}{b}} \cdot -0.5 \]
  5. Applied rewrites65.9%

    \[\leadsto \color{blue}{\frac{c}{b} \cdot -0.5} \]
  6. Final simplification65.9%

    \[\leadsto -0.5 \cdot \frac{c}{b} \]
  7. Add Preprocessing

Alternative 5: 64.9% accurate, 2.9× speedup?

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

\\
\frac{-0.5}{b} \cdot c
\end{array}
Derivation
  1. Initial program 53.7%

    \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]
  2. Add Preprocessing
  3. Taylor expanded in c around 0

    \[\leadsto \color{blue}{\frac{-1}{2} \cdot \frac{c}{b}} \]
  4. Step-by-step derivation
    1. *-commutativeN/A

      \[\leadsto \color{blue}{\frac{c}{b} \cdot \frac{-1}{2}} \]
    2. lower-*.f64N/A

      \[\leadsto \color{blue}{\frac{c}{b} \cdot \frac{-1}{2}} \]
    3. lower-/.f6465.9

      \[\leadsto \color{blue}{\frac{c}{b}} \cdot -0.5 \]
  5. Applied rewrites65.9%

    \[\leadsto \color{blue}{\frac{c}{b} \cdot -0.5} \]
  6. Step-by-step derivation
    1. Applied rewrites65.9%

      \[\leadsto c \cdot \color{blue}{\frac{-0.5}{b}} \]
    2. Final simplification65.9%

      \[\leadsto \frac{-0.5}{b} \cdot c \]
    3. Add Preprocessing

    Reproduce

    ?
    herbie shell --seed 2024236 
    (FPCore (a b c)
      :name "Cubic critical, narrow range"
      :precision binary64
      :pre (and (and (and (< 1.0536712127723509e-8 a) (< a 94906265.62425156)) (and (< 1.0536712127723509e-8 b) (< b 94906265.62425156))) (and (< 1.0536712127723509e-8 c) (< c 94906265.62425156)))
      (/ (+ (- b) (sqrt (- (* b b) (* (* 3.0 a) c)))) (* 3.0 a)))