Cubic critical, medium range

Percentage Accurate: 31.1% → 99.4%
Time: 14.2s
Alternatives: 6
Speedup: 2.9×

Specification

?
\[\left(\left(1.1102230246251565 \cdot 10^{-16} < a \land a < 9007199254740992\right) \land \left(1.1102230246251565 \cdot 10^{-16} < b \land b < 9007199254740992\right)\right) \land \left(1.1102230246251565 \cdot 10^{-16} < c \land c < 9007199254740992\right)\]
\[\begin{array}{l} \\ \frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \end{array} \]
(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 6 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: 31.1% 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, 0.8× speedup?

\[\begin{array}{l} \\ \frac{c}{a \cdot \left(\left(b + \sqrt{\mathsf{fma}\left(c, a \cdot -3, b \cdot b\right)}\right) \cdot \frac{-1}{a}\right)} \end{array} \]
(FPCore (a b c)
 :precision binary64
 (/ c (* a (* (+ b (sqrt (fma c (* a -3.0) (* b b)))) (/ -1.0 a)))))
double code(double a, double b, double c) {
	return c / (a * ((b + sqrt(fma(c, (a * -3.0), (b * b)))) * (-1.0 / a)));
}
function code(a, b, c)
	return Float64(c / Float64(a * Float64(Float64(b + sqrt(fma(c, Float64(a * -3.0), Float64(b * b)))) * Float64(-1.0 / a))))
end
code[a_, b_, c_] := N[(c / N[(a * N[(N[(b + N[Sqrt[N[(c * N[(a * -3.0), $MachinePrecision] + N[(b * b), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * N[(-1.0 / a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{c}{a \cdot \left(\left(b + \sqrt{\mathsf{fma}\left(c, a \cdot -3, b \cdot b\right)}\right) \cdot \frac{-1}{a}\right)}
\end{array}
Derivation
  1. Initial program 30.3%

    \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]
  2. Add Preprocessing
  3. Applied egg-rr30.3%

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

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

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

      \[\leadsto \frac{\color{blue}{\frac{\frac{b}{a} \cdot \frac{b}{a} - \frac{\sqrt{a \cdot \left(-3 \cdot c\right) + b \cdot b}}{a} \cdot \frac{\sqrt{a \cdot \left(-3 \cdot c\right) + b \cdot b}}{a}}{\frac{b}{a} + \frac{\sqrt{a \cdot \left(-3 \cdot c\right) + b \cdot b}}{a}}}}{-3} \]
  5. Applied egg-rr30.1%

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

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

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

      \[\leadsto \frac{\frac{3 \cdot \color{blue}{\frac{c}{a}}}{\frac{b}{a} + \frac{\sqrt{\mathsf{fma}\left(c, a \cdot -3, b \cdot b\right)}}{a}}}{-3} \]
  8. Simplified99.2%

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

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

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

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

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

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

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

      \[\leadsto -1 \cdot \frac{c}{\color{blue}{\left(\frac{b}{a} + \frac{\sqrt{c \cdot \left(a \cdot -3\right) + b \cdot b}}{a}\right) \cdot a}} \]
  10. Applied egg-rr99.4%

    \[\leadsto \color{blue}{-1 \cdot \frac{c}{\left(\frac{1}{a} \cdot \left(b + \sqrt{\mathsf{fma}\left(c, a \cdot -3, b \cdot b\right)}\right)\right) \cdot a}} \]
  11. Final simplification99.4%

    \[\leadsto \frac{c}{a \cdot \left(\left(b + \sqrt{\mathsf{fma}\left(c, a \cdot -3, b \cdot b\right)}\right) \cdot \frac{-1}{a}\right)} \]
  12. Add Preprocessing

Alternative 2: 91.0% accurate, 0.9× speedup?

\[\begin{array}{l} \\ \mathsf{fma}\left(a, \frac{-0.375 \cdot \left(c \cdot c\right)}{b \cdot \left(b \cdot b\right)}, -0.5 \cdot \frac{c}{b}\right) \end{array} \]
(FPCore (a b c)
 :precision binary64
 (fma a (/ (* -0.375 (* c c)) (* b (* b b))) (* -0.5 (/ c b))))
double code(double a, double b, double c) {
	return fma(a, ((-0.375 * (c * c)) / (b * (b * b))), (-0.5 * (c / b)));
}
function code(a, b, c)
	return fma(a, Float64(Float64(-0.375 * Float64(c * c)) / Float64(b * Float64(b * b))), Float64(-0.5 * Float64(c / b)))
end
code[a_, b_, c_] := N[(a * N[(N[(-0.375 * N[(c * c), $MachinePrecision]), $MachinePrecision] / N[(b * N[(b * b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(-0.5 * N[(c / b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\mathsf{fma}\left(a, \frac{-0.375 \cdot \left(c \cdot c\right)}{b \cdot \left(b \cdot b\right)}, -0.5 \cdot \frac{c}{b}\right)
\end{array}
Derivation
  1. Initial program 30.3%

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

    \[\leadsto \color{blue}{\frac{-1}{2} \cdot \frac{c}{b} + a \cdot \left(\frac{-3}{8} \cdot \frac{{c}^{2}}{{b}^{3}} + a \cdot \left(\frac{-9}{16} \cdot \frac{{c}^{3}}{{b}^{5}} + \frac{-1}{6} \cdot \frac{a \cdot \left(\frac{81}{64} \cdot \frac{{c}^{4}}{{b}^{6}} + \frac{81}{16} \cdot \frac{{c}^{4}}{{b}^{6}}\right)}{b}\right)\right)} \]
  4. Simplified96.5%

    \[\leadsto \color{blue}{\mathsf{fma}\left(a, \mathsf{fma}\left(a, \mathsf{fma}\left(\frac{\frac{{c}^{4}}{{b}^{6}} \cdot \left(6.328125 \cdot a\right)}{b}, -0.16666666666666666, \frac{\left(c \cdot \left(c \cdot c\right)\right) \cdot -0.5625}{{b}^{5}}\right), \frac{\left(c \cdot c\right) \cdot -0.375}{b \cdot \left(b \cdot b\right)}\right), -0.5 \cdot \frac{c}{b}\right)} \]
  5. Taylor expanded in a around 0

    \[\leadsto \mathsf{fma}\left(a, \color{blue}{\frac{-3}{8} \cdot \frac{{c}^{2}}{{b}^{3}}}, \frac{-1}{2} \cdot \frac{c}{b}\right) \]
  6. Step-by-step derivation
    1. associate-*r/N/A

      \[\leadsto \mathsf{fma}\left(a, \color{blue}{\frac{\frac{-3}{8} \cdot {c}^{2}}{{b}^{3}}}, \frac{-1}{2} \cdot \frac{c}{b}\right) \]
    2. /-lowering-/.f64N/A

      \[\leadsto \mathsf{fma}\left(a, \color{blue}{\frac{\frac{-3}{8} \cdot {c}^{2}}{{b}^{3}}}, \frac{-1}{2} \cdot \frac{c}{b}\right) \]
    3. *-lowering-*.f64N/A

      \[\leadsto \mathsf{fma}\left(a, \frac{\color{blue}{\frac{-3}{8} \cdot {c}^{2}}}{{b}^{3}}, \frac{-1}{2} \cdot \frac{c}{b}\right) \]
    4. unpow2N/A

      \[\leadsto \mathsf{fma}\left(a, \frac{\frac{-3}{8} \cdot \color{blue}{\left(c \cdot c\right)}}{{b}^{3}}, \frac{-1}{2} \cdot \frac{c}{b}\right) \]
    5. *-lowering-*.f64N/A

      \[\leadsto \mathsf{fma}\left(a, \frac{\frac{-3}{8} \cdot \color{blue}{\left(c \cdot c\right)}}{{b}^{3}}, \frac{-1}{2} \cdot \frac{c}{b}\right) \]
    6. cube-multN/A

      \[\leadsto \mathsf{fma}\left(a, \frac{\frac{-3}{8} \cdot \left(c \cdot c\right)}{\color{blue}{b \cdot \left(b \cdot b\right)}}, \frac{-1}{2} \cdot \frac{c}{b}\right) \]
    7. unpow2N/A

      \[\leadsto \mathsf{fma}\left(a, \frac{\frac{-3}{8} \cdot \left(c \cdot c\right)}{b \cdot \color{blue}{{b}^{2}}}, \frac{-1}{2} \cdot \frac{c}{b}\right) \]
    8. *-lowering-*.f64N/A

      \[\leadsto \mathsf{fma}\left(a, \frac{\frac{-3}{8} \cdot \left(c \cdot c\right)}{\color{blue}{b \cdot {b}^{2}}}, \frac{-1}{2} \cdot \frac{c}{b}\right) \]
    9. unpow2N/A

      \[\leadsto \mathsf{fma}\left(a, \frac{\frac{-3}{8} \cdot \left(c \cdot c\right)}{b \cdot \color{blue}{\left(b \cdot b\right)}}, \frac{-1}{2} \cdot \frac{c}{b}\right) \]
    10. *-lowering-*.f6491.3

      \[\leadsto \mathsf{fma}\left(a, \frac{-0.375 \cdot \left(c \cdot c\right)}{b \cdot \color{blue}{\left(b \cdot b\right)}}, -0.5 \cdot \frac{c}{b}\right) \]
  7. Simplified91.3%

    \[\leadsto \mathsf{fma}\left(a, \color{blue}{\frac{-0.375 \cdot \left(c \cdot c\right)}{b \cdot \left(b \cdot b\right)}}, -0.5 \cdot \frac{c}{b}\right) \]
  8. Add Preprocessing

Alternative 3: 91.0% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \frac{\mathsf{fma}\left(a, \frac{-0.375 \cdot \left(c \cdot c\right)}{b \cdot b}, c \cdot -0.5\right)}{b} \end{array} \]
(FPCore (a b c)
 :precision binary64
 (/ (fma a (/ (* -0.375 (* c c)) (* b b)) (* c -0.5)) b))
double code(double a, double b, double c) {
	return fma(a, ((-0.375 * (c * c)) / (b * b)), (c * -0.5)) / b;
}
function code(a, b, c)
	return Float64(fma(a, Float64(Float64(-0.375 * Float64(c * c)) / Float64(b * b)), Float64(c * -0.5)) / b)
end
code[a_, b_, c_] := N[(N[(a * N[(N[(-0.375 * N[(c * c), $MachinePrecision]), $MachinePrecision] / N[(b * b), $MachinePrecision]), $MachinePrecision] + N[(c * -0.5), $MachinePrecision]), $MachinePrecision] / b), $MachinePrecision]
\begin{array}{l}

\\
\frac{\mathsf{fma}\left(a, \frac{-0.375 \cdot \left(c \cdot c\right)}{b \cdot b}, c \cdot -0.5\right)}{b}
\end{array}
Derivation
  1. Initial program 30.3%

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

    \[\leadsto \color{blue}{\frac{\frac{-1}{2} \cdot c + \frac{-3}{8} \cdot \frac{a \cdot {c}^{2}}{{b}^{2}}}{b}} \]
  4. Step-by-step derivation
    1. /-lowering-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{-1}{2} \cdot c + \frac{-3}{8} \cdot \frac{a \cdot {c}^{2}}{{b}^{2}}}{b}} \]
  5. Simplified91.2%

    \[\leadsto \color{blue}{\frac{\mathsf{fma}\left(a, \frac{\left(c \cdot c\right) \cdot -0.375}{b \cdot b}, c \cdot -0.5\right)}{b}} \]
  6. Final simplification91.2%

    \[\leadsto \frac{\mathsf{fma}\left(a, \frac{-0.375 \cdot \left(c \cdot c\right)}{b \cdot b}, c \cdot -0.5\right)}{b} \]
  7. Add Preprocessing

Alternative 4: 91.0% accurate, 1.1× speedup?

\[\begin{array}{l} \\ \frac{c \cdot \mathsf{fma}\left(-0.375, \frac{c \cdot a}{b \cdot b}, -0.5\right)}{b} \end{array} \]
(FPCore (a b c)
 :precision binary64
 (/ (* c (fma -0.375 (/ (* c a) (* b b)) -0.5)) b))
double code(double a, double b, double c) {
	return (c * fma(-0.375, ((c * a) / (b * b)), -0.5)) / b;
}
function code(a, b, c)
	return Float64(Float64(c * fma(-0.375, Float64(Float64(c * a) / Float64(b * b)), -0.5)) / b)
end
code[a_, b_, c_] := N[(N[(c * N[(-0.375 * N[(N[(c * a), $MachinePrecision] / N[(b * b), $MachinePrecision]), $MachinePrecision] + -0.5), $MachinePrecision]), $MachinePrecision] / b), $MachinePrecision]
\begin{array}{l}

\\
\frac{c \cdot \mathsf{fma}\left(-0.375, \frac{c \cdot a}{b \cdot b}, -0.5\right)}{b}
\end{array}
Derivation
  1. Initial program 30.3%

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

    \[\leadsto \color{blue}{\frac{-1}{2} \cdot \frac{c}{b} + a \cdot \left(\frac{-3}{8} \cdot \frac{{c}^{2}}{{b}^{3}} + a \cdot \left(\frac{-9}{16} \cdot \frac{{c}^{3}}{{b}^{5}} + \frac{-1}{6} \cdot \frac{a \cdot \left(\frac{81}{64} \cdot \frac{{c}^{4}}{{b}^{6}} + \frac{81}{16} \cdot \frac{{c}^{4}}{{b}^{6}}\right)}{b}\right)\right)} \]
  4. Simplified96.5%

    \[\leadsto \color{blue}{\mathsf{fma}\left(a, \mathsf{fma}\left(a, \mathsf{fma}\left(\frac{\frac{{c}^{4}}{{b}^{6}} \cdot \left(6.328125 \cdot a\right)}{b}, -0.16666666666666666, \frac{\left(c \cdot \left(c \cdot c\right)\right) \cdot -0.5625}{{b}^{5}}\right), \frac{\left(c \cdot c\right) \cdot -0.375}{b \cdot \left(b \cdot b\right)}\right), -0.5 \cdot \frac{c}{b}\right)} \]
  5. Applied egg-rr96.5%

    \[\leadsto \color{blue}{\mathsf{fma}\left(\mathsf{fma}\left(c, c \cdot \frac{-0.375}{b \cdot \left(b \cdot b\right)}, a \cdot \mathsf{fma}\left(c, \left(c \cdot c\right) \cdot \frac{-0.5625}{\left(b \cdot b\right) \cdot \left(b \cdot \left(b \cdot b\right)\right)}, \frac{\left(c \cdot \left(c \cdot \left(c \cdot c\right)\right)\right) \cdot \left(6.328125 \cdot a\right)}{\left(\left(b \cdot b\right) \cdot \left(b \cdot \left(b \cdot b\right)\right)\right) \cdot \left(b \cdot b\right)} \cdot -0.16666666666666666\right)\right), a, \frac{c \cdot -0.5}{b}\right)} \]
  6. Taylor expanded in b around inf

    \[\leadsto \color{blue}{\frac{\frac{-1}{2} \cdot c + \frac{-3}{8} \cdot \frac{a \cdot {c}^{2}}{{b}^{2}}}{b}} \]
  7. Step-by-step derivation
    1. /-lowering-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{-1}{2} \cdot c + \frac{-3}{8} \cdot \frac{a \cdot {c}^{2}}{{b}^{2}}}{b}} \]
    2. *-commutativeN/A

      \[\leadsto \frac{\color{blue}{c \cdot \frac{-1}{2}} + \frac{-3}{8} \cdot \frac{a \cdot {c}^{2}}{{b}^{2}}}{b} \]
    3. accelerator-lowering-fma.f64N/A

      \[\leadsto \frac{\color{blue}{\mathsf{fma}\left(c, \frac{-1}{2}, \frac{-3}{8} \cdot \frac{a \cdot {c}^{2}}{{b}^{2}}\right)}}{b} \]
    4. associate-*r/N/A

      \[\leadsto \frac{\mathsf{fma}\left(c, \frac{-1}{2}, \color{blue}{\frac{\frac{-3}{8} \cdot \left(a \cdot {c}^{2}\right)}{{b}^{2}}}\right)}{b} \]
    5. /-lowering-/.f64N/A

      \[\leadsto \frac{\mathsf{fma}\left(c, \frac{-1}{2}, \color{blue}{\frac{\frac{-3}{8} \cdot \left(a \cdot {c}^{2}\right)}{{b}^{2}}}\right)}{b} \]
    6. *-lowering-*.f64N/A

      \[\leadsto \frac{\mathsf{fma}\left(c, \frac{-1}{2}, \frac{\color{blue}{\frac{-3}{8} \cdot \left(a \cdot {c}^{2}\right)}}{{b}^{2}}\right)}{b} \]
    7. *-lowering-*.f64N/A

      \[\leadsto \frac{\mathsf{fma}\left(c, \frac{-1}{2}, \frac{\frac{-3}{8} \cdot \color{blue}{\left(a \cdot {c}^{2}\right)}}{{b}^{2}}\right)}{b} \]
    8. unpow2N/A

      \[\leadsto \frac{\mathsf{fma}\left(c, \frac{-1}{2}, \frac{\frac{-3}{8} \cdot \left(a \cdot \color{blue}{\left(c \cdot c\right)}\right)}{{b}^{2}}\right)}{b} \]
    9. *-lowering-*.f64N/A

      \[\leadsto \frac{\mathsf{fma}\left(c, \frac{-1}{2}, \frac{\frac{-3}{8} \cdot \left(a \cdot \color{blue}{\left(c \cdot c\right)}\right)}{{b}^{2}}\right)}{b} \]
    10. unpow2N/A

      \[\leadsto \frac{\mathsf{fma}\left(c, \frac{-1}{2}, \frac{\frac{-3}{8} \cdot \left(a \cdot \left(c \cdot c\right)\right)}{\color{blue}{b \cdot b}}\right)}{b} \]
    11. *-lowering-*.f6491.2

      \[\leadsto \frac{\mathsf{fma}\left(c, -0.5, \frac{-0.375 \cdot \left(a \cdot \left(c \cdot c\right)\right)}{\color{blue}{b \cdot b}}\right)}{b} \]
  8. Simplified91.2%

    \[\leadsto \color{blue}{\frac{\mathsf{fma}\left(c, -0.5, \frac{-0.375 \cdot \left(a \cdot \left(c \cdot c\right)\right)}{b \cdot b}\right)}{b}} \]
  9. Taylor expanded in c around 0

    \[\leadsto \frac{\color{blue}{c \cdot \left(\frac{-3}{8} \cdot \frac{a \cdot c}{{b}^{2}} - \frac{1}{2}\right)}}{b} \]
  10. Step-by-step derivation
    1. *-lowering-*.f64N/A

      \[\leadsto \frac{\color{blue}{c \cdot \left(\frac{-3}{8} \cdot \frac{a \cdot c}{{b}^{2}} - \frac{1}{2}\right)}}{b} \]
    2. sub-negN/A

      \[\leadsto \frac{c \cdot \color{blue}{\left(\frac{-3}{8} \cdot \frac{a \cdot c}{{b}^{2}} + \left(\mathsf{neg}\left(\frac{1}{2}\right)\right)\right)}}{b} \]
    3. metadata-evalN/A

      \[\leadsto \frac{c \cdot \left(\frac{-3}{8} \cdot \frac{a \cdot c}{{b}^{2}} + \color{blue}{\frac{-1}{2}}\right)}{b} \]
    4. accelerator-lowering-fma.f64N/A

      \[\leadsto \frac{c \cdot \color{blue}{\mathsf{fma}\left(\frac{-3}{8}, \frac{a \cdot c}{{b}^{2}}, \frac{-1}{2}\right)}}{b} \]
    5. /-lowering-/.f64N/A

      \[\leadsto \frac{c \cdot \mathsf{fma}\left(\frac{-3}{8}, \color{blue}{\frac{a \cdot c}{{b}^{2}}}, \frac{-1}{2}\right)}{b} \]
    6. *-commutativeN/A

      \[\leadsto \frac{c \cdot \mathsf{fma}\left(\frac{-3}{8}, \frac{\color{blue}{c \cdot a}}{{b}^{2}}, \frac{-1}{2}\right)}{b} \]
    7. *-lowering-*.f64N/A

      \[\leadsto \frac{c \cdot \mathsf{fma}\left(\frac{-3}{8}, \frac{\color{blue}{c \cdot a}}{{b}^{2}}, \frac{-1}{2}\right)}{b} \]
    8. unpow2N/A

      \[\leadsto \frac{c \cdot \mathsf{fma}\left(\frac{-3}{8}, \frac{c \cdot a}{\color{blue}{b \cdot b}}, \frac{-1}{2}\right)}{b} \]
    9. *-lowering-*.f6491.2

      \[\leadsto \frac{c \cdot \mathsf{fma}\left(-0.375, \frac{c \cdot a}{\color{blue}{b \cdot b}}, -0.5\right)}{b} \]
  11. Simplified91.2%

    \[\leadsto \frac{\color{blue}{c \cdot \mathsf{fma}\left(-0.375, \frac{c \cdot a}{b \cdot b}, -0.5\right)}}{b} \]
  12. Add Preprocessing

Alternative 5: 81.6% 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 30.3%

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

    \[\leadsto \color{blue}{\frac{-1}{2} \cdot \frac{c}{b}} \]
  4. Step-by-step derivation
    1. *-lowering-*.f64N/A

      \[\leadsto \color{blue}{\frac{-1}{2} \cdot \frac{c}{b}} \]
    2. /-lowering-/.f6482.0

      \[\leadsto -0.5 \cdot \color{blue}{\frac{c}{b}} \]
  5. Simplified82.0%

    \[\leadsto \color{blue}{-0.5 \cdot \frac{c}{b}} \]
  6. Add Preprocessing

Alternative 6: 3.2% accurate, 50.0× speedup?

\[\begin{array}{l} \\ 0 \end{array} \]
(FPCore (a b c) :precision binary64 0.0)
double code(double a, double b, double c) {
	return 0.0;
}
real(8) function code(a, b, c)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    real(8), intent (in) :: c
    code = 0.0d0
end function
public static double code(double a, double b, double c) {
	return 0.0;
}
def code(a, b, c):
	return 0.0
function code(a, b, c)
	return 0.0
end
function tmp = code(a, b, c)
	tmp = 0.0;
end
code[a_, b_, c_] := 0.0
\begin{array}{l}

\\
0
\end{array}
Derivation
  1. Initial program 30.3%

    \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]
  2. Add Preprocessing
  3. Applied egg-rr30.3%

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

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

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

      \[\leadsto \color{blue}{\frac{\frac{b - \sqrt{a \cdot \left(-3 \cdot c\right) + b \cdot b}}{-3}}{a}} \]
  5. Applied egg-rr30.3%

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

      \[\leadsto \mathsf{fma}\left(\frac{b}{a}, \frac{-1}{3}, \color{blue}{\frac{\sqrt{c \cdot \left(a \cdot -3\right) + b \cdot b}}{a} \cdot \frac{1}{3}}\right) \]
  7. Applied egg-rr31.6%

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

    \[\leadsto \color{blue}{\frac{-1}{3} \cdot \frac{b}{a} + \frac{1}{3} \cdot \frac{b}{a}} \]
  9. Step-by-step derivation
    1. distribute-rgt-outN/A

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

      \[\leadsto \frac{b}{a} \cdot \color{blue}{0} \]
    3. mul0-rgt3.2

      \[\leadsto \color{blue}{0} \]
  10. Simplified3.2%

    \[\leadsto \color{blue}{0} \]
  11. Add Preprocessing

Reproduce

?
herbie shell --seed 2024198 
(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)))