Quadratic roots, wide range

Percentage Accurate: 17.8% → 99.7%
Time: 10.3s
Alternatives: 5
Speedup: 3.6×

Specification

?
\[\left(\left(4.930380657631324 \cdot 10^{-32} < a \land a < 2.028240960365167 \cdot 10^{+31}\right) \land \left(4.930380657631324 \cdot 10^{-32} < b \land b < 2.028240960365167 \cdot 10^{+31}\right)\right) \land \left(4.930380657631324 \cdot 10^{-32} < c \land c < 2.028240960365167 \cdot 10^{+31}\right)\]
\[\begin{array}{l} \\ \frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a} \end{array} \]
(FPCore (a b c)
 :precision binary64
 (/ (+ (- b) (sqrt (- (* b b) (* (* 4.0 a) c)))) (* 2.0 a)))
double code(double a, double b, double c) {
	return (-b + sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * 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) - ((4.0d0 * a) * c)))) / (2.0d0 * a)
end function
public static double code(double a, double b, double c) {
	return (-b + Math.sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * a);
}
def code(a, b, c):
	return (-b + math.sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * a)
function code(a, b, c)
	return Float64(Float64(Float64(-b) + sqrt(Float64(Float64(b * b) - Float64(Float64(4.0 * a) * c)))) / Float64(2.0 * a))
end
function tmp = code(a, b, c)
	tmp = (-b + sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * a);
end
code[a_, b_, c_] := N[(N[((-b) + N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(N[(4.0 * a), $MachinePrecision] * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(2.0 * a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \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?

\[\begin{array}{l} \\ \frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a} \end{array} \]
(FPCore (a b c)
 :precision binary64
 (/ (+ (- b) (sqrt (- (* b b) (* (* 4.0 a) c)))) (* 2.0 a)))
double code(double a, double b, double c) {
	return (-b + sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * 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) - ((4.0d0 * a) * c)))) / (2.0d0 * a)
end function
public static double code(double a, double b, double c) {
	return (-b + Math.sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * a);
}
def code(a, b, c):
	return (-b + math.sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * a)
function code(a, b, c)
	return Float64(Float64(Float64(-b) + sqrt(Float64(Float64(b * b) - Float64(Float64(4.0 * a) * c)))) / Float64(2.0 * a))
end
function tmp = code(a, b, c)
	tmp = (-b + sqrt(((b * b) - ((4.0 * a) * c)))) / (2.0 * a);
end
code[a_, b_, c_] := N[(N[((-b) + N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(N[(4.0 * a), $MachinePrecision] * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(2.0 * a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a}
\end{array}

Alternative 1: 99.7% accurate, 0.8× speedup?

\[\begin{array}{l} \\ \frac{\frac{\left(c \cdot a\right) \cdot -2}{a}}{\sqrt{\mathsf{fma}\left(a, -4 \cdot c, b \cdot b\right)} + b} \end{array} \]
(FPCore (a b c)
 :precision binary64
 (/ (/ (* (* c a) -2.0) a) (+ (sqrt (fma a (* -4.0 c) (* b b))) b)))
double code(double a, double b, double c) {
	return (((c * a) * -2.0) / a) / (sqrt(fma(a, (-4.0 * c), (b * b))) + b);
}
function code(a, b, c)
	return Float64(Float64(Float64(Float64(c * a) * -2.0) / a) / Float64(sqrt(fma(a, Float64(-4.0 * c), Float64(b * b))) + b))
end
code[a_, b_, c_] := N[(N[(N[(N[(c * a), $MachinePrecision] * -2.0), $MachinePrecision] / a), $MachinePrecision] / N[(N[Sqrt[N[(a * N[(-4.0 * c), $MachinePrecision] + N[(b * b), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] + b), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{\frac{\left(c \cdot a\right) \cdot -2}{a}}{\sqrt{\mathsf{fma}\left(a, -4 \cdot c, b \cdot b\right)} + b}
\end{array}
Derivation
  1. Initial program 17.3%

    \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a} \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a}} \]
    2. clear-numN/A

      \[\leadsto \color{blue}{\frac{1}{\frac{2 \cdot a}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}}} \]
    3. lift-*.f64N/A

      \[\leadsto \frac{1}{\frac{\color{blue}{2 \cdot a}}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}} \]
    4. associate-/l*N/A

      \[\leadsto \frac{1}{\color{blue}{2 \cdot \frac{a}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}}} \]
    5. associate-/r*N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{2}}{\frac{a}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}}} \]
    6. metadata-evalN/A

      \[\leadsto \frac{\color{blue}{\frac{1}{2}}}{\frac{a}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}} \]
    7. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{2}}{\frac{a}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}}} \]
    8. lower-/.f6417.3

      \[\leadsto \frac{0.5}{\color{blue}{\frac{a}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}}} \]
    9. lift-+.f64N/A

      \[\leadsto \frac{\frac{1}{2}}{\frac{a}{\color{blue}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}}} \]
    10. +-commutativeN/A

      \[\leadsto \frac{\frac{1}{2}}{\frac{a}{\color{blue}{\sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c} + \left(-b\right)}}} \]
    11. lift-neg.f64N/A

      \[\leadsto \frac{\frac{1}{2}}{\frac{a}{\sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c} + \color{blue}{\left(\mathsf{neg}\left(b\right)\right)}}} \]
    12. unsub-negN/A

      \[\leadsto \frac{\frac{1}{2}}{\frac{a}{\color{blue}{\sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c} - b}}} \]
    13. lower--.f6417.3

      \[\leadsto \frac{0.5}{\frac{a}{\color{blue}{\sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c} - b}}} \]
  4. Applied rewrites17.3%

    \[\leadsto \color{blue}{\frac{0.5}{\frac{a}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b}}} \]
  5. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{2}}{\frac{a}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b}}} \]
    2. lift-/.f64N/A

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

      \[\leadsto \color{blue}{\frac{\frac{1}{2}}{a} \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b\right)} \]
    4. lift--.f64N/A

      \[\leadsto \frac{\frac{1}{2}}{a} \cdot \color{blue}{\left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b\right)} \]
    5. flip--N/A

      \[\leadsto \frac{\frac{1}{2}}{a} \cdot \color{blue}{\frac{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b \cdot b}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b}} \]
    6. lift-+.f64N/A

      \[\leadsto \frac{\frac{1}{2}}{a} \cdot \frac{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b \cdot b}{\color{blue}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b}} \]
    7. frac-timesN/A

      \[\leadsto \color{blue}{\frac{\frac{1}{2} \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b \cdot b\right)}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)}} \]
    8. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{2} \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b \cdot b\right)}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)}} \]
  6. Applied rewrites99.4%

    \[\leadsto \color{blue}{\frac{0.5 \cdot \mathsf{fma}\left(-4 \cdot c, a, 0\right)}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)}} \]
  7. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{2} \cdot \mathsf{fma}\left(-4 \cdot c, a, 0\right)}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)}} \]
    2. lift-*.f64N/A

      \[\leadsto \frac{\frac{1}{2} \cdot \mathsf{fma}\left(-4 \cdot c, a, 0\right)}{\color{blue}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)}} \]
    3. associate-/r*N/A

      \[\leadsto \color{blue}{\frac{\frac{\frac{1}{2} \cdot \mathsf{fma}\left(-4 \cdot c, a, 0\right)}{a}}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b}} \]
    4. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{\frac{1}{2} \cdot \mathsf{fma}\left(-4 \cdot c, a, 0\right)}{a}}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b}} \]
    5. lower-/.f6499.7

      \[\leadsto \frac{\color{blue}{\frac{0.5 \cdot \mathsf{fma}\left(-4 \cdot c, a, 0\right)}{a}}}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b} \]
    6. lift-*.f64N/A

      \[\leadsto \frac{\frac{\color{blue}{\frac{1}{2} \cdot \mathsf{fma}\left(-4 \cdot c, a, 0\right)}}{a}}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b} \]
    7. lift-fma.f64N/A

      \[\leadsto \frac{\frac{\frac{1}{2} \cdot \color{blue}{\left(\left(-4 \cdot c\right) \cdot a + 0\right)}}{a}}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b} \]
    8. +-rgt-identityN/A

      \[\leadsto \frac{\frac{\frac{1}{2} \cdot \color{blue}{\left(\left(-4 \cdot c\right) \cdot a\right)}}{a}}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b} \]
    9. lift-*.f64N/A

      \[\leadsto \frac{\frac{\frac{1}{2} \cdot \left(\color{blue}{\left(-4 \cdot c\right)} \cdot a\right)}{a}}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b} \]
    10. associate-*l*N/A

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

      \[\leadsto \frac{\frac{\color{blue}{\left(\frac{1}{2} \cdot -4\right) \cdot \left(c \cdot a\right)}}{a}}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b} \]
    12. metadata-evalN/A

      \[\leadsto \frac{\frac{\color{blue}{-2} \cdot \left(c \cdot a\right)}{a}}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b} \]
    13. metadata-evalN/A

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

      \[\leadsto \frac{\frac{\color{blue}{\left(\mathsf{neg}\left(2\right)\right) \cdot \left(c \cdot a\right)}}{a}}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b} \]
    15. metadata-evalN/A

      \[\leadsto \frac{\frac{\color{blue}{-2} \cdot \left(c \cdot a\right)}{a}}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b} \]
    16. *-commutativeN/A

      \[\leadsto \frac{\frac{-2 \cdot \color{blue}{\left(a \cdot c\right)}}{a}}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b} \]
    17. lower-*.f6499.7

      \[\leadsto \frac{\frac{-2 \cdot \color{blue}{\left(a \cdot c\right)}}{a}}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b} \]
  8. Applied rewrites99.7%

    \[\leadsto \color{blue}{\frac{\frac{-2 \cdot \left(a \cdot c\right)}{a}}{\sqrt{\mathsf{fma}\left(a, c \cdot -4, b \cdot b\right)} + b}} \]
  9. Final simplification99.7%

    \[\leadsto \frac{\frac{\left(c \cdot a\right) \cdot -2}{a}}{\sqrt{\mathsf{fma}\left(a, -4 \cdot c, b \cdot b\right)} + b} \]
  10. Add Preprocessing

Alternative 2: 99.4% accurate, 0.9× speedup?

\[\begin{array}{l} \\ \frac{\left(c \cdot a\right) \cdot -2}{\left(\sqrt{\mathsf{fma}\left(a, -4 \cdot c, b \cdot b\right)} + b\right) \cdot a} \end{array} \]
(FPCore (a b c)
 :precision binary64
 (/ (* (* c a) -2.0) (* (+ (sqrt (fma a (* -4.0 c) (* b b))) b) a)))
double code(double a, double b, double c) {
	return ((c * a) * -2.0) / ((sqrt(fma(a, (-4.0 * c), (b * b))) + b) * a);
}
function code(a, b, c)
	return Float64(Float64(Float64(c * a) * -2.0) / Float64(Float64(sqrt(fma(a, Float64(-4.0 * c), Float64(b * b))) + b) * a))
end
code[a_, b_, c_] := N[(N[(N[(c * a), $MachinePrecision] * -2.0), $MachinePrecision] / N[(N[(N[Sqrt[N[(a * N[(-4.0 * c), $MachinePrecision] + N[(b * b), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] + b), $MachinePrecision] * a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{\left(c \cdot a\right) \cdot -2}{\left(\sqrt{\mathsf{fma}\left(a, -4 \cdot c, b \cdot b\right)} + b\right) \cdot a}
\end{array}
Derivation
  1. Initial program 17.3%

    \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a} \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a}} \]
    2. clear-numN/A

      \[\leadsto \color{blue}{\frac{1}{\frac{2 \cdot a}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}}} \]
    3. lift-*.f64N/A

      \[\leadsto \frac{1}{\frac{\color{blue}{2 \cdot a}}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}} \]
    4. associate-/l*N/A

      \[\leadsto \frac{1}{\color{blue}{2 \cdot \frac{a}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}}} \]
    5. associate-/r*N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{2}}{\frac{a}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}}} \]
    6. metadata-evalN/A

      \[\leadsto \frac{\color{blue}{\frac{1}{2}}}{\frac{a}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}} \]
    7. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{2}}{\frac{a}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}}} \]
    8. lower-/.f6417.3

      \[\leadsto \frac{0.5}{\color{blue}{\frac{a}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}}} \]
    9. lift-+.f64N/A

      \[\leadsto \frac{\frac{1}{2}}{\frac{a}{\color{blue}{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}}} \]
    10. +-commutativeN/A

      \[\leadsto \frac{\frac{1}{2}}{\frac{a}{\color{blue}{\sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c} + \left(-b\right)}}} \]
    11. lift-neg.f64N/A

      \[\leadsto \frac{\frac{1}{2}}{\frac{a}{\sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c} + \color{blue}{\left(\mathsf{neg}\left(b\right)\right)}}} \]
    12. unsub-negN/A

      \[\leadsto \frac{\frac{1}{2}}{\frac{a}{\color{blue}{\sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c} - b}}} \]
    13. lower--.f6417.3

      \[\leadsto \frac{0.5}{\frac{a}{\color{blue}{\sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c} - b}}} \]
  4. Applied rewrites17.3%

    \[\leadsto \color{blue}{\frac{0.5}{\frac{a}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b}}} \]
  5. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{2}}{\frac{a}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b}}} \]
    2. lift-/.f64N/A

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

      \[\leadsto \color{blue}{\frac{\frac{1}{2}}{a} \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b\right)} \]
    4. lift--.f64N/A

      \[\leadsto \frac{\frac{1}{2}}{a} \cdot \color{blue}{\left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b\right)} \]
    5. flip--N/A

      \[\leadsto \frac{\frac{1}{2}}{a} \cdot \color{blue}{\frac{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b \cdot b}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b}} \]
    6. lift-+.f64N/A

      \[\leadsto \frac{\frac{1}{2}}{a} \cdot \frac{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b \cdot b}{\color{blue}{\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b}} \]
    7. frac-timesN/A

      \[\leadsto \color{blue}{\frac{\frac{1}{2} \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b \cdot b\right)}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)}} \]
    8. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{2} \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} \cdot \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b \cdot b\right)}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)}} \]
  6. Applied rewrites99.4%

    \[\leadsto \color{blue}{\frac{0.5 \cdot \mathsf{fma}\left(-4 \cdot c, a, 0\right)}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)}} \]
  7. Step-by-step derivation
    1. lift-*.f64N/A

      \[\leadsto \frac{\color{blue}{\frac{1}{2} \cdot \mathsf{fma}\left(-4 \cdot c, a, 0\right)}}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)} \]
    2. lift-fma.f64N/A

      \[\leadsto \frac{\frac{1}{2} \cdot \color{blue}{\left(\left(-4 \cdot c\right) \cdot a + 0\right)}}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)} \]
    3. +-rgt-identityN/A

      \[\leadsto \frac{\frac{1}{2} \cdot \color{blue}{\left(\left(-4 \cdot c\right) \cdot a\right)}}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)} \]
    4. lift-*.f64N/A

      \[\leadsto \frac{\frac{1}{2} \cdot \left(\color{blue}{\left(-4 \cdot c\right)} \cdot a\right)}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)} \]
    5. associate-*l*N/A

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

      \[\leadsto \frac{\color{blue}{\left(\frac{1}{2} \cdot -4\right) \cdot \left(c \cdot a\right)}}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)} \]
    7. metadata-evalN/A

      \[\leadsto \frac{\color{blue}{-2} \cdot \left(c \cdot a\right)}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)} \]
    8. metadata-evalN/A

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

      \[\leadsto \frac{\color{blue}{\left(\mathsf{neg}\left(2\right)\right) \cdot \left(c \cdot a\right)}}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)} \]
    10. metadata-evalN/A

      \[\leadsto \frac{\color{blue}{-2} \cdot \left(c \cdot a\right)}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)} \]
    11. *-commutativeN/A

      \[\leadsto \frac{-2 \cdot \color{blue}{\left(a \cdot c\right)}}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)} \]
    12. lower-*.f6499.4

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

      \[\leadsto \frac{-2 \cdot \left(a \cdot c\right)}{\color{blue}{a \cdot \left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right)}} \]
    14. *-commutativeN/A

      \[\leadsto \frac{-2 \cdot \left(a \cdot c\right)}{\color{blue}{\left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right) \cdot a}} \]
    15. lower-*.f6499.4

      \[\leadsto \frac{-2 \cdot \left(a \cdot c\right)}{\color{blue}{\left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + b\right) \cdot a}} \]
    16. lift-fma.f64N/A

      \[\leadsto \frac{-2 \cdot \left(a \cdot c\right)}{\left(\sqrt{\color{blue}{\left(-4 \cdot c\right) \cdot a + b \cdot b}} + b\right) \cdot a} \]
    17. *-commutativeN/A

      \[\leadsto \frac{-2 \cdot \left(a \cdot c\right)}{\left(\sqrt{\color{blue}{a \cdot \left(-4 \cdot c\right)} + b \cdot b} + b\right) \cdot a} \]
    18. lower-fma.f6499.4

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

      \[\leadsto \frac{-2 \cdot \left(a \cdot c\right)}{\left(\sqrt{\mathsf{fma}\left(a, \color{blue}{-4 \cdot c}, b \cdot b\right)} + b\right) \cdot a} \]
    20. *-commutativeN/A

      \[\leadsto \frac{-2 \cdot \left(a \cdot c\right)}{\left(\sqrt{\mathsf{fma}\left(a, \color{blue}{c \cdot -4}, b \cdot b\right)} + b\right) \cdot a} \]
    21. lower-*.f6499.4

      \[\leadsto \frac{-2 \cdot \left(a \cdot c\right)}{\left(\sqrt{\mathsf{fma}\left(a, \color{blue}{c \cdot -4}, b \cdot b\right)} + b\right) \cdot a} \]
  8. Applied rewrites99.4%

    \[\leadsto \color{blue}{\frac{-2 \cdot \left(a \cdot c\right)}{\left(\sqrt{\mathsf{fma}\left(a, c \cdot -4, b \cdot b\right)} + b\right) \cdot a}} \]
  9. Final simplification99.4%

    \[\leadsto \frac{\left(c \cdot a\right) \cdot -2}{\left(\sqrt{\mathsf{fma}\left(a, -4 \cdot c, b \cdot b\right)} + b\right) \cdot a} \]
  10. Add Preprocessing

Alternative 3: 95.2% accurate, 1.2× speedup?

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

\\
\frac{\mathsf{fma}\left(c, \frac{c \cdot a}{b \cdot b}, c\right)}{-b}
\end{array}
Derivation
  1. Initial program 17.3%

    \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a} \]
  2. Add Preprocessing
  3. Taylor expanded in a around 0

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

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

      \[\leadsto \color{blue}{-1 \cdot \frac{c}{b} - \frac{a \cdot {c}^{2}}{{b}^{3}}} \]
    3. associate-*r/N/A

      \[\leadsto \color{blue}{\frac{-1 \cdot c}{b}} - \frac{a \cdot {c}^{2}}{{b}^{3}} \]
    4. unpow3N/A

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

      \[\leadsto \frac{-1 \cdot c}{b} - \frac{a \cdot {c}^{2}}{\color{blue}{{b}^{2}} \cdot b} \]
    6. associate-/r*N/A

      \[\leadsto \frac{-1 \cdot c}{b} - \color{blue}{\frac{\frac{a \cdot {c}^{2}}{{b}^{2}}}{b}} \]
    7. div-subN/A

      \[\leadsto \color{blue}{\frac{-1 \cdot c - \frac{a \cdot {c}^{2}}{{b}^{2}}}{b}} \]
    8. unsub-negN/A

      \[\leadsto \frac{\color{blue}{-1 \cdot c + \left(\mathsf{neg}\left(\frac{a \cdot {c}^{2}}{{b}^{2}}\right)\right)}}{b} \]
    9. mul-1-negN/A

      \[\leadsto \frac{-1 \cdot c + \color{blue}{-1 \cdot \frac{a \cdot {c}^{2}}{{b}^{2}}}}{b} \]
    10. distribute-lft-outN/A

      \[\leadsto \frac{\color{blue}{-1 \cdot \left(c + \frac{a \cdot {c}^{2}}{{b}^{2}}\right)}}{b} \]
    11. associate-/l*N/A

      \[\leadsto \color{blue}{-1 \cdot \frac{c + \frac{a \cdot {c}^{2}}{{b}^{2}}}{b}} \]
    12. mul-1-negN/A

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

      \[\leadsto \color{blue}{-\frac{c + \frac{a \cdot {c}^{2}}{{b}^{2}}}{b}} \]
    14. lower-/.f64N/A

      \[\leadsto -\color{blue}{\frac{c + \frac{a \cdot {c}^{2}}{{b}^{2}}}{b}} \]
  5. Applied rewrites95.5%

    \[\leadsto \color{blue}{-\frac{\mathsf{fma}\left(\frac{c}{b}, \frac{c \cdot a}{b}, c\right)}{b}} \]
  6. Step-by-step derivation
    1. Applied rewrites95.5%

      \[\leadsto -\frac{\mathsf{fma}\left(c, \frac{a \cdot c}{b \cdot b}, c\right)}{b} \]
    2. Final simplification95.5%

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

    Alternative 4: 90.4% accurate, 3.6× speedup?

    \[\begin{array}{l} \\ \frac{-c}{b} \end{array} \]
    (FPCore (a b c) :precision binary64 (/ (- c) b))
    double code(double a, double b, double c) {
    	return -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 = -c / b
    end function
    
    public static double code(double a, double b, double c) {
    	return -c / b;
    }
    
    def code(a, b, c):
    	return -c / b
    
    function code(a, b, c)
    	return Float64(Float64(-c) / b)
    end
    
    function tmp = code(a, b, c)
    	tmp = -c / b;
    end
    
    code[a_, b_, c_] := N[((-c) / b), $MachinePrecision]
    
    \begin{array}{l}
    
    \\
    \frac{-c}{b}
    \end{array}
    
    Derivation
    1. Initial program 17.3%

      \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a} \]
    2. Add Preprocessing
    3. Taylor expanded in a around 0

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

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

        \[\leadsto \color{blue}{\frac{-1 \cdot c}{b}} \]
      3. mul-1-negN/A

        \[\leadsto \frac{\color{blue}{\mathsf{neg}\left(c\right)}}{b} \]
      4. lower-neg.f6490.7

        \[\leadsto \frac{\color{blue}{-c}}{b} \]
    5. Applied rewrites90.7%

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

    Alternative 5: 3.3% 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 17.3%

      \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a} \]
    2. Add Preprocessing
    3. Applied rewrites14.8%

      \[\leadsto \color{blue}{\left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b\right) \cdot \frac{b - \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)}}{\left(b - \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)}\right) \cdot \left(2 \cdot a\right)}} \]
    4. Step-by-step derivation
      1. lift-*.f64N/A

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

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

        \[\leadsto \frac{b - \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)}}{\left(b - \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)}\right) \cdot \left(2 \cdot a\right)} \cdot \color{blue}{\left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} - b\right)} \]
      4. sub-negN/A

        \[\leadsto \frac{b - \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)}}{\left(b - \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)}\right) \cdot \left(2 \cdot a\right)} \cdot \color{blue}{\left(\sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)} + \left(\mathsf{neg}\left(b\right)\right)\right)} \]
      5. distribute-lft-inN/A

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

        \[\leadsto \color{blue}{\mathsf{fma}\left(\frac{b - \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)}}{\left(b - \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)}\right) \cdot \left(2 \cdot a\right)}, \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)}, \frac{b - \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)}}{\left(b - \sqrt{\mathsf{fma}\left(-4 \cdot c, a, b \cdot b\right)}\right) \cdot \left(2 \cdot a\right)} \cdot \left(\mathsf{neg}\left(b\right)\right)\right)} \]
    5. Applied rewrites19.1%

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

      \[\leadsto \color{blue}{\frac{-1}{2} \cdot \frac{b}{a} + \frac{1}{2} \cdot \frac{b}{a}} \]
    7. Step-by-step derivation
      1. distribute-rgt-outN/A

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

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

        \[\leadsto \color{blue}{0} \]
    8. Applied rewrites3.3%

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

    Reproduce

    ?
    herbie shell --seed 2024282 
    (FPCore (a b c)
      :name "Quadratic roots, 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) (* (* 4.0 a) c)))) (* 2.0 a)))