quad2p (problem 3.2.1, positive)

Percentage Accurate: 52.5% → 84.6%
Time: 10.1s
Alternatives: 6
Speedup: 11.2×

Specification

?
\[\begin{array}{l} \\ \frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \end{array} \]
(FPCore (a b_2 c)
 :precision binary64
 (/ (+ (- b_2) (sqrt (- (* b_2 b_2) (* a c)))) a))
double code(double a, double b_2, double c) {
	return (-b_2 + sqrt(((b_2 * b_2) - (a * c)))) / a;
}
real(8) function code(a, b_2, c)
    real(8), intent (in) :: a
    real(8), intent (in) :: b_2
    real(8), intent (in) :: c
    code = (-b_2 + sqrt(((b_2 * b_2) - (a * c)))) / a
end function
public static double code(double a, double b_2, double c) {
	return (-b_2 + Math.sqrt(((b_2 * b_2) - (a * c)))) / a;
}
def code(a, b_2, c):
	return (-b_2 + math.sqrt(((b_2 * b_2) - (a * c)))) / a
function code(a, b_2, c)
	return Float64(Float64(Float64(-b_2) + sqrt(Float64(Float64(b_2 * b_2) - Float64(a * c)))) / a)
end
function tmp = code(a, b_2, c)
	tmp = (-b_2 + sqrt(((b_2 * b_2) - (a * c)))) / a;
end
code[a_, b$95$2_, c_] := N[(N[((-b$95$2) + N[Sqrt[N[(N[(b$95$2 * b$95$2), $MachinePrecision] - N[(a * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / a), $MachinePrecision]
\begin{array}{l}

\\
\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{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: 52.5% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \end{array} \]
(FPCore (a b_2 c)
 :precision binary64
 (/ (+ (- b_2) (sqrt (- (* b_2 b_2) (* a c)))) a))
double code(double a, double b_2, double c) {
	return (-b_2 + sqrt(((b_2 * b_2) - (a * c)))) / a;
}
real(8) function code(a, b_2, c)
    real(8), intent (in) :: a
    real(8), intent (in) :: b_2
    real(8), intent (in) :: c
    code = (-b_2 + sqrt(((b_2 * b_2) - (a * c)))) / a
end function
public static double code(double a, double b_2, double c) {
	return (-b_2 + Math.sqrt(((b_2 * b_2) - (a * c)))) / a;
}
def code(a, b_2, c):
	return (-b_2 + math.sqrt(((b_2 * b_2) - (a * c)))) / a
function code(a, b_2, c)
	return Float64(Float64(Float64(-b_2) + sqrt(Float64(Float64(b_2 * b_2) - Float64(a * c)))) / a)
end
function tmp = code(a, b_2, c)
	tmp = (-b_2 + sqrt(((b_2 * b_2) - (a * c)))) / a;
end
code[a_, b$95$2_, c_] := N[(N[((-b$95$2) + N[Sqrt[N[(N[(b$95$2 * b$95$2), $MachinePrecision] - N[(a * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / a), $MachinePrecision]
\begin{array}{l}

\\
\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a}
\end{array}

Alternative 1: 84.6% accurate, 0.8× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;b\_2 \leq -1.36 \cdot 10^{+38}:\\ \;\;\;\;-2 \cdot \frac{b\_2}{a}\\ \mathbf{elif}\;b\_2 \leq 6.5 \cdot 10^{-71}:\\ \;\;\;\;\frac{\sqrt{b\_2 \cdot b\_2 - a \cdot c} - b\_2}{a}\\ \mathbf{elif}\;b\_2 \leq 10^{-24}:\\ \;\;\;\;-0.5 \cdot \frac{c}{b\_2}\\ \mathbf{elif}\;b\_2 \leq 1.5 \cdot 10^{-14}:\\ \;\;\;\;\frac{\sqrt{a \cdot \left(-c\right)} - b\_2}{a}\\ \mathbf{else}:\\ \;\;\;\;c \cdot \frac{\mathsf{fma}\left(-0.125, \frac{c}{b\_2} \cdot \frac{a}{b\_2}, -0.5\right)}{b\_2}\\ \end{array} \end{array} \]
(FPCore (a b_2 c)
 :precision binary64
 (if (<= b_2 -1.36e+38)
   (* -2.0 (/ b_2 a))
   (if (<= b_2 6.5e-71)
     (/ (- (sqrt (- (* b_2 b_2) (* a c))) b_2) a)
     (if (<= b_2 1e-24)
       (* -0.5 (/ c b_2))
       (if (<= b_2 1.5e-14)
         (/ (- (sqrt (* a (- c))) b_2) a)
         (* c (/ (fma -0.125 (* (/ c b_2) (/ a b_2)) -0.5) b_2)))))))
double code(double a, double b_2, double c) {
	double tmp;
	if (b_2 <= -1.36e+38) {
		tmp = -2.0 * (b_2 / a);
	} else if (b_2 <= 6.5e-71) {
		tmp = (sqrt(((b_2 * b_2) - (a * c))) - b_2) / a;
	} else if (b_2 <= 1e-24) {
		tmp = -0.5 * (c / b_2);
	} else if (b_2 <= 1.5e-14) {
		tmp = (sqrt((a * -c)) - b_2) / a;
	} else {
		tmp = c * (fma(-0.125, ((c / b_2) * (a / b_2)), -0.5) / b_2);
	}
	return tmp;
}
function code(a, b_2, c)
	tmp = 0.0
	if (b_2 <= -1.36e+38)
		tmp = Float64(-2.0 * Float64(b_2 / a));
	elseif (b_2 <= 6.5e-71)
		tmp = Float64(Float64(sqrt(Float64(Float64(b_2 * b_2) - Float64(a * c))) - b_2) / a);
	elseif (b_2 <= 1e-24)
		tmp = Float64(-0.5 * Float64(c / b_2));
	elseif (b_2 <= 1.5e-14)
		tmp = Float64(Float64(sqrt(Float64(a * Float64(-c))) - b_2) / a);
	else
		tmp = Float64(c * Float64(fma(-0.125, Float64(Float64(c / b_2) * Float64(a / b_2)), -0.5) / b_2));
	end
	return tmp
end
code[a_, b$95$2_, c_] := If[LessEqual[b$95$2, -1.36e+38], N[(-2.0 * N[(b$95$2 / a), $MachinePrecision]), $MachinePrecision], If[LessEqual[b$95$2, 6.5e-71], N[(N[(N[Sqrt[N[(N[(b$95$2 * b$95$2), $MachinePrecision] - N[(a * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] - b$95$2), $MachinePrecision] / a), $MachinePrecision], If[LessEqual[b$95$2, 1e-24], N[(-0.5 * N[(c / b$95$2), $MachinePrecision]), $MachinePrecision], If[LessEqual[b$95$2, 1.5e-14], N[(N[(N[Sqrt[N[(a * (-c)), $MachinePrecision]], $MachinePrecision] - b$95$2), $MachinePrecision] / a), $MachinePrecision], N[(c * N[(N[(-0.125 * N[(N[(c / b$95$2), $MachinePrecision] * N[(a / b$95$2), $MachinePrecision]), $MachinePrecision] + -0.5), $MachinePrecision] / b$95$2), $MachinePrecision]), $MachinePrecision]]]]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;b\_2 \leq -1.36 \cdot 10^{+38}:\\
\;\;\;\;-2 \cdot \frac{b\_2}{a}\\

\mathbf{elif}\;b\_2 \leq 6.5 \cdot 10^{-71}:\\
\;\;\;\;\frac{\sqrt{b\_2 \cdot b\_2 - a \cdot c} - b\_2}{a}\\

\mathbf{elif}\;b\_2 \leq 10^{-24}:\\
\;\;\;\;-0.5 \cdot \frac{c}{b\_2}\\

\mathbf{elif}\;b\_2 \leq 1.5 \cdot 10^{-14}:\\
\;\;\;\;\frac{\sqrt{a \cdot \left(-c\right)} - b\_2}{a}\\

\mathbf{else}:\\
\;\;\;\;c \cdot \frac{\mathsf{fma}\left(-0.125, \frac{c}{b\_2} \cdot \frac{a}{b\_2}, -0.5\right)}{b\_2}\\


\end{array}
\end{array}
Derivation
  1. Split input into 5 regimes
  2. if b_2 < -1.36000000000000002e38

    1. Initial program 61.8%

      \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
    2. Add Preprocessing
    3. Taylor expanded in b_2 around -inf 95.8%

      \[\leadsto \color{blue}{-2 \cdot \frac{b\_2}{a}} \]

    if -1.36000000000000002e38 < b_2 < 6.50000000000000005e-71

    1. Initial program 85.4%

      \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
    2. Add Preprocessing

    if 6.50000000000000005e-71 < b_2 < 9.99999999999999924e-25

    1. Initial program 15.7%

      \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
    2. Add Preprocessing
    3. Taylor expanded in b_2 around inf 76.0%

      \[\leadsto \color{blue}{-0.5 \cdot \frac{c}{b\_2}} \]

    if 9.99999999999999924e-25 < b_2 < 1.4999999999999999e-14

    1. Initial program 99.7%

      \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
    2. Add Preprocessing
    3. Taylor expanded in b_2 around 0 99.7%

      \[\leadsto \frac{\left(-b\_2\right) + \sqrt{\color{blue}{-1 \cdot \left(a \cdot c\right)}}}{a} \]
    4. Step-by-step derivation
      1. mul-1-neg99.7%

        \[\leadsto \frac{\left(-b\_2\right) + \sqrt{\color{blue}{-a \cdot c}}}{a} \]
    5. Simplified99.7%

      \[\leadsto \frac{\left(-b\_2\right) + \sqrt{\color{blue}{-a \cdot c}}}{a} \]

    if 1.4999999999999999e-14 < b_2

    1. Initial program 10.8%

      \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
    2. Add Preprocessing
    3. Taylor expanded in c around 0 86.7%

      \[\leadsto \color{blue}{c \cdot \left(-0.125 \cdot \frac{a \cdot c}{{b\_2}^{3}} - 0.5 \cdot \frac{1}{b\_2}\right)} \]
    4. Taylor expanded in b_2 around inf 86.7%

      \[\leadsto c \cdot \color{blue}{\frac{-0.125 \cdot \frac{a \cdot c}{{b\_2}^{2}} - 0.5}{b\_2}} \]
    5. Step-by-step derivation
      1. fma-neg86.7%

        \[\leadsto c \cdot \frac{\color{blue}{\mathsf{fma}\left(-0.125, \frac{a \cdot c}{{b\_2}^{2}}, -0.5\right)}}{b\_2} \]
      2. associate-/l*91.2%

        \[\leadsto c \cdot \frac{\mathsf{fma}\left(-0.125, \color{blue}{a \cdot \frac{c}{{b\_2}^{2}}}, -0.5\right)}{b\_2} \]
      3. metadata-eval91.2%

        \[\leadsto c \cdot \frac{\mathsf{fma}\left(-0.125, a \cdot \frac{c}{{b\_2}^{2}}, \color{blue}{-0.5}\right)}{b\_2} \]
    6. Simplified91.2%

      \[\leadsto c \cdot \color{blue}{\frac{\mathsf{fma}\left(-0.125, a \cdot \frac{c}{{b\_2}^{2}}, -0.5\right)}{b\_2}} \]
    7. Step-by-step derivation
      1. associate-*r/86.7%

        \[\leadsto c \cdot \frac{\mathsf{fma}\left(-0.125, \color{blue}{\frac{a \cdot c}{{b\_2}^{2}}}, -0.5\right)}{b\_2} \]
      2. *-commutative86.7%

        \[\leadsto c \cdot \frac{\mathsf{fma}\left(-0.125, \frac{\color{blue}{c \cdot a}}{{b\_2}^{2}}, -0.5\right)}{b\_2} \]
      3. unpow286.7%

        \[\leadsto c \cdot \frac{\mathsf{fma}\left(-0.125, \frac{c \cdot a}{\color{blue}{b\_2 \cdot b\_2}}, -0.5\right)}{b\_2} \]
      4. times-frac91.4%

        \[\leadsto c \cdot \frac{\mathsf{fma}\left(-0.125, \color{blue}{\frac{c}{b\_2} \cdot \frac{a}{b\_2}}, -0.5\right)}{b\_2} \]
    8. Applied egg-rr91.4%

      \[\leadsto c \cdot \frac{\mathsf{fma}\left(-0.125, \color{blue}{\frac{c}{b\_2} \cdot \frac{a}{b\_2}}, -0.5\right)}{b\_2} \]
  3. Recombined 5 regimes into one program.
  4. Final simplification90.3%

    \[\leadsto \begin{array}{l} \mathbf{if}\;b\_2 \leq -1.36 \cdot 10^{+38}:\\ \;\;\;\;-2 \cdot \frac{b\_2}{a}\\ \mathbf{elif}\;b\_2 \leq 6.5 \cdot 10^{-71}:\\ \;\;\;\;\frac{\sqrt{b\_2 \cdot b\_2 - a \cdot c} - b\_2}{a}\\ \mathbf{elif}\;b\_2 \leq 10^{-24}:\\ \;\;\;\;-0.5 \cdot \frac{c}{b\_2}\\ \mathbf{elif}\;b\_2 \leq 1.5 \cdot 10^{-14}:\\ \;\;\;\;\frac{\sqrt{a \cdot \left(-c\right)} - b\_2}{a}\\ \mathbf{else}:\\ \;\;\;\;c \cdot \frac{\mathsf{fma}\left(-0.125, \frac{c}{b\_2} \cdot \frac{a}{b\_2}, -0.5\right)}{b\_2}\\ \end{array} \]
  5. Add Preprocessing

Alternative 2: 84.9% accurate, 0.9× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;b\_2 \leq -1.36 \cdot 10^{+38}:\\ \;\;\;\;-2 \cdot \frac{b\_2}{a}\\ \mathbf{elif}\;b\_2 \leq 3.9 \cdot 10^{-69}:\\ \;\;\;\;\frac{\sqrt{b\_2 \cdot b\_2 - a \cdot c} - b\_2}{a}\\ \mathbf{elif}\;b\_2 \leq 1.65 \cdot 10^{-21} \lor \neg \left(b\_2 \leq 2.8 \cdot 10^{-15}\right):\\ \;\;\;\;-0.5 \cdot \frac{c}{b\_2}\\ \mathbf{else}:\\ \;\;\;\;\frac{\sqrt{a \cdot \left(-c\right)} - b\_2}{a}\\ \end{array} \end{array} \]
(FPCore (a b_2 c)
 :precision binary64
 (if (<= b_2 -1.36e+38)
   (* -2.0 (/ b_2 a))
   (if (<= b_2 3.9e-69)
     (/ (- (sqrt (- (* b_2 b_2) (* a c))) b_2) a)
     (if (or (<= b_2 1.65e-21) (not (<= b_2 2.8e-15)))
       (* -0.5 (/ c b_2))
       (/ (- (sqrt (* a (- c))) b_2) a)))))
double code(double a, double b_2, double c) {
	double tmp;
	if (b_2 <= -1.36e+38) {
		tmp = -2.0 * (b_2 / a);
	} else if (b_2 <= 3.9e-69) {
		tmp = (sqrt(((b_2 * b_2) - (a * c))) - b_2) / a;
	} else if ((b_2 <= 1.65e-21) || !(b_2 <= 2.8e-15)) {
		tmp = -0.5 * (c / b_2);
	} else {
		tmp = (sqrt((a * -c)) - b_2) / a;
	}
	return tmp;
}
real(8) function code(a, b_2, c)
    real(8), intent (in) :: a
    real(8), intent (in) :: b_2
    real(8), intent (in) :: c
    real(8) :: tmp
    if (b_2 <= (-1.36d+38)) then
        tmp = (-2.0d0) * (b_2 / a)
    else if (b_2 <= 3.9d-69) then
        tmp = (sqrt(((b_2 * b_2) - (a * c))) - b_2) / a
    else if ((b_2 <= 1.65d-21) .or. (.not. (b_2 <= 2.8d-15))) then
        tmp = (-0.5d0) * (c / b_2)
    else
        tmp = (sqrt((a * -c)) - b_2) / a
    end if
    code = tmp
end function
public static double code(double a, double b_2, double c) {
	double tmp;
	if (b_2 <= -1.36e+38) {
		tmp = -2.0 * (b_2 / a);
	} else if (b_2 <= 3.9e-69) {
		tmp = (Math.sqrt(((b_2 * b_2) - (a * c))) - b_2) / a;
	} else if ((b_2 <= 1.65e-21) || !(b_2 <= 2.8e-15)) {
		tmp = -0.5 * (c / b_2);
	} else {
		tmp = (Math.sqrt((a * -c)) - b_2) / a;
	}
	return tmp;
}
def code(a, b_2, c):
	tmp = 0
	if b_2 <= -1.36e+38:
		tmp = -2.0 * (b_2 / a)
	elif b_2 <= 3.9e-69:
		tmp = (math.sqrt(((b_2 * b_2) - (a * c))) - b_2) / a
	elif (b_2 <= 1.65e-21) or not (b_2 <= 2.8e-15):
		tmp = -0.5 * (c / b_2)
	else:
		tmp = (math.sqrt((a * -c)) - b_2) / a
	return tmp
function code(a, b_2, c)
	tmp = 0.0
	if (b_2 <= -1.36e+38)
		tmp = Float64(-2.0 * Float64(b_2 / a));
	elseif (b_2 <= 3.9e-69)
		tmp = Float64(Float64(sqrt(Float64(Float64(b_2 * b_2) - Float64(a * c))) - b_2) / a);
	elseif ((b_2 <= 1.65e-21) || !(b_2 <= 2.8e-15))
		tmp = Float64(-0.5 * Float64(c / b_2));
	else
		tmp = Float64(Float64(sqrt(Float64(a * Float64(-c))) - b_2) / a);
	end
	return tmp
end
function tmp_2 = code(a, b_2, c)
	tmp = 0.0;
	if (b_2 <= -1.36e+38)
		tmp = -2.0 * (b_2 / a);
	elseif (b_2 <= 3.9e-69)
		tmp = (sqrt(((b_2 * b_2) - (a * c))) - b_2) / a;
	elseif ((b_2 <= 1.65e-21) || ~((b_2 <= 2.8e-15)))
		tmp = -0.5 * (c / b_2);
	else
		tmp = (sqrt((a * -c)) - b_2) / a;
	end
	tmp_2 = tmp;
end
code[a_, b$95$2_, c_] := If[LessEqual[b$95$2, -1.36e+38], N[(-2.0 * N[(b$95$2 / a), $MachinePrecision]), $MachinePrecision], If[LessEqual[b$95$2, 3.9e-69], N[(N[(N[Sqrt[N[(N[(b$95$2 * b$95$2), $MachinePrecision] - N[(a * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] - b$95$2), $MachinePrecision] / a), $MachinePrecision], If[Or[LessEqual[b$95$2, 1.65e-21], N[Not[LessEqual[b$95$2, 2.8e-15]], $MachinePrecision]], N[(-0.5 * N[(c / b$95$2), $MachinePrecision]), $MachinePrecision], N[(N[(N[Sqrt[N[(a * (-c)), $MachinePrecision]], $MachinePrecision] - b$95$2), $MachinePrecision] / a), $MachinePrecision]]]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;b\_2 \leq -1.36 \cdot 10^{+38}:\\
\;\;\;\;-2 \cdot \frac{b\_2}{a}\\

\mathbf{elif}\;b\_2 \leq 3.9 \cdot 10^{-69}:\\
\;\;\;\;\frac{\sqrt{b\_2 \cdot b\_2 - a \cdot c} - b\_2}{a}\\

\mathbf{elif}\;b\_2 \leq 1.65 \cdot 10^{-21} \lor \neg \left(b\_2 \leq 2.8 \cdot 10^{-15}\right):\\
\;\;\;\;-0.5 \cdot \frac{c}{b\_2}\\

\mathbf{else}:\\
\;\;\;\;\frac{\sqrt{a \cdot \left(-c\right)} - b\_2}{a}\\


\end{array}
\end{array}
Derivation
  1. Split input into 4 regimes
  2. if b_2 < -1.36000000000000002e38

    1. Initial program 61.8%

      \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
    2. Add Preprocessing
    3. Taylor expanded in b_2 around -inf 95.8%

      \[\leadsto \color{blue}{-2 \cdot \frac{b\_2}{a}} \]

    if -1.36000000000000002e38 < b_2 < 3.89999999999999981e-69

    1. Initial program 85.4%

      \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
    2. Add Preprocessing

    if 3.89999999999999981e-69 < b_2 < 1.65000000000000004e-21 or 2.80000000000000014e-15 < b_2

    1. Initial program 11.2%

      \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
    2. Add Preprocessing
    3. Taylor expanded in b_2 around inf 89.6%

      \[\leadsto \color{blue}{-0.5 \cdot \frac{c}{b\_2}} \]

    if 1.65000000000000004e-21 < b_2 < 2.80000000000000014e-15

    1. Initial program 99.7%

      \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
    2. Add Preprocessing
    3. Taylor expanded in b_2 around 0 99.7%

      \[\leadsto \frac{\left(-b\_2\right) + \sqrt{\color{blue}{-1 \cdot \left(a \cdot c\right)}}}{a} \]
    4. Step-by-step derivation
      1. mul-1-neg99.7%

        \[\leadsto \frac{\left(-b\_2\right) + \sqrt{\color{blue}{-a \cdot c}}}{a} \]
    5. Simplified99.7%

      \[\leadsto \frac{\left(-b\_2\right) + \sqrt{\color{blue}{-a \cdot c}}}{a} \]
  3. Recombined 4 regimes into one program.
  4. Final simplification90.1%

    \[\leadsto \begin{array}{l} \mathbf{if}\;b\_2 \leq -1.36 \cdot 10^{+38}:\\ \;\;\;\;-2 \cdot \frac{b\_2}{a}\\ \mathbf{elif}\;b\_2 \leq 3.9 \cdot 10^{-69}:\\ \;\;\;\;\frac{\sqrt{b\_2 \cdot b\_2 - a \cdot c} - b\_2}{a}\\ \mathbf{elif}\;b\_2 \leq 1.65 \cdot 10^{-21} \lor \neg \left(b\_2 \leq 2.8 \cdot 10^{-15}\right):\\ \;\;\;\;-0.5 \cdot \frac{c}{b\_2}\\ \mathbf{else}:\\ \;\;\;\;\frac{\sqrt{a \cdot \left(-c\right)} - b\_2}{a}\\ \end{array} \]
  5. Add Preprocessing

Alternative 3: 80.3% accurate, 0.9× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;b\_2 \leq -2.9 \cdot 10^{-5}:\\ \;\;\;\;-2 \cdot \frac{b\_2}{a}\\ \mathbf{elif}\;b\_2 \leq 8 \cdot 10^{-72}:\\ \;\;\;\;\frac{\sqrt{a \cdot \left(-c\right)} - b\_2}{a}\\ \mathbf{else}:\\ \;\;\;\;-0.5 \cdot \frac{c}{b\_2}\\ \end{array} \end{array} \]
(FPCore (a b_2 c)
 :precision binary64
 (if (<= b_2 -2.9e-5)
   (* -2.0 (/ b_2 a))
   (if (<= b_2 8e-72) (/ (- (sqrt (* a (- c))) b_2) a) (* -0.5 (/ c b_2)))))
double code(double a, double b_2, double c) {
	double tmp;
	if (b_2 <= -2.9e-5) {
		tmp = -2.0 * (b_2 / a);
	} else if (b_2 <= 8e-72) {
		tmp = (sqrt((a * -c)) - b_2) / a;
	} else {
		tmp = -0.5 * (c / b_2);
	}
	return tmp;
}
real(8) function code(a, b_2, c)
    real(8), intent (in) :: a
    real(8), intent (in) :: b_2
    real(8), intent (in) :: c
    real(8) :: tmp
    if (b_2 <= (-2.9d-5)) then
        tmp = (-2.0d0) * (b_2 / a)
    else if (b_2 <= 8d-72) then
        tmp = (sqrt((a * -c)) - b_2) / a
    else
        tmp = (-0.5d0) * (c / b_2)
    end if
    code = tmp
end function
public static double code(double a, double b_2, double c) {
	double tmp;
	if (b_2 <= -2.9e-5) {
		tmp = -2.0 * (b_2 / a);
	} else if (b_2 <= 8e-72) {
		tmp = (Math.sqrt((a * -c)) - b_2) / a;
	} else {
		tmp = -0.5 * (c / b_2);
	}
	return tmp;
}
def code(a, b_2, c):
	tmp = 0
	if b_2 <= -2.9e-5:
		tmp = -2.0 * (b_2 / a)
	elif b_2 <= 8e-72:
		tmp = (math.sqrt((a * -c)) - b_2) / a
	else:
		tmp = -0.5 * (c / b_2)
	return tmp
function code(a, b_2, c)
	tmp = 0.0
	if (b_2 <= -2.9e-5)
		tmp = Float64(-2.0 * Float64(b_2 / a));
	elseif (b_2 <= 8e-72)
		tmp = Float64(Float64(sqrt(Float64(a * Float64(-c))) - b_2) / a);
	else
		tmp = Float64(-0.5 * Float64(c / b_2));
	end
	return tmp
end
function tmp_2 = code(a, b_2, c)
	tmp = 0.0;
	if (b_2 <= -2.9e-5)
		tmp = -2.0 * (b_2 / a);
	elseif (b_2 <= 8e-72)
		tmp = (sqrt((a * -c)) - b_2) / a;
	else
		tmp = -0.5 * (c / b_2);
	end
	tmp_2 = tmp;
end
code[a_, b$95$2_, c_] := If[LessEqual[b$95$2, -2.9e-5], N[(-2.0 * N[(b$95$2 / a), $MachinePrecision]), $MachinePrecision], If[LessEqual[b$95$2, 8e-72], N[(N[(N[Sqrt[N[(a * (-c)), $MachinePrecision]], $MachinePrecision] - b$95$2), $MachinePrecision] / a), $MachinePrecision], N[(-0.5 * N[(c / b$95$2), $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;b\_2 \leq -2.9 \cdot 10^{-5}:\\
\;\;\;\;-2 \cdot \frac{b\_2}{a}\\

\mathbf{elif}\;b\_2 \leq 8 \cdot 10^{-72}:\\
\;\;\;\;\frac{\sqrt{a \cdot \left(-c\right)} - b\_2}{a}\\

\mathbf{else}:\\
\;\;\;\;-0.5 \cdot \frac{c}{b\_2}\\


\end{array}
\end{array}
Derivation
  1. Split input into 3 regimes
  2. if b_2 < -2.9e-5

    1. Initial program 65.9%

      \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
    2. Add Preprocessing
    3. Taylor expanded in b_2 around -inf 92.0%

      \[\leadsto \color{blue}{-2 \cdot \frac{b\_2}{a}} \]

    if -2.9e-5 < b_2 < 7.9999999999999997e-72

    1. Initial program 85.3%

      \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
    2. Add Preprocessing
    3. Taylor expanded in b_2 around 0 77.0%

      \[\leadsto \frac{\left(-b\_2\right) + \sqrt{\color{blue}{-1 \cdot \left(a \cdot c\right)}}}{a} \]
    4. Step-by-step derivation
      1. mul-1-neg77.0%

        \[\leadsto \frac{\left(-b\_2\right) + \sqrt{\color{blue}{-a \cdot c}}}{a} \]
    5. Simplified77.0%

      \[\leadsto \frac{\left(-b\_2\right) + \sqrt{\color{blue}{-a \cdot c}}}{a} \]

    if 7.9999999999999997e-72 < b_2

    1. Initial program 15.5%

      \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
    2. Add Preprocessing
    3. Taylor expanded in b_2 around inf 85.4%

      \[\leadsto \color{blue}{-0.5 \cdot \frac{c}{b\_2}} \]
  3. Recombined 3 regimes into one program.
  4. Final simplification85.2%

    \[\leadsto \begin{array}{l} \mathbf{if}\;b\_2 \leq -2.9 \cdot 10^{-5}:\\ \;\;\;\;-2 \cdot \frac{b\_2}{a}\\ \mathbf{elif}\;b\_2 \leq 8 \cdot 10^{-72}:\\ \;\;\;\;\frac{\sqrt{a \cdot \left(-c\right)} - b\_2}{a}\\ \mathbf{else}:\\ \;\;\;\;-0.5 \cdot \frac{c}{b\_2}\\ \end{array} \]
  5. Add Preprocessing

Alternative 4: 67.5% accurate, 11.2× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;b\_2 \leq -5 \cdot 10^{-310}:\\ \;\;\;\;-2 \cdot \frac{b\_2}{a}\\ \mathbf{else}:\\ \;\;\;\;-0.5 \cdot \frac{c}{b\_2}\\ \end{array} \end{array} \]
(FPCore (a b_2 c)
 :precision binary64
 (if (<= b_2 -5e-310) (* -2.0 (/ b_2 a)) (* -0.5 (/ c b_2))))
double code(double a, double b_2, double c) {
	double tmp;
	if (b_2 <= -5e-310) {
		tmp = -2.0 * (b_2 / a);
	} else {
		tmp = -0.5 * (c / b_2);
	}
	return tmp;
}
real(8) function code(a, b_2, c)
    real(8), intent (in) :: a
    real(8), intent (in) :: b_2
    real(8), intent (in) :: c
    real(8) :: tmp
    if (b_2 <= (-5d-310)) then
        tmp = (-2.0d0) * (b_2 / a)
    else
        tmp = (-0.5d0) * (c / b_2)
    end if
    code = tmp
end function
public static double code(double a, double b_2, double c) {
	double tmp;
	if (b_2 <= -5e-310) {
		tmp = -2.0 * (b_2 / a);
	} else {
		tmp = -0.5 * (c / b_2);
	}
	return tmp;
}
def code(a, b_2, c):
	tmp = 0
	if b_2 <= -5e-310:
		tmp = -2.0 * (b_2 / a)
	else:
		tmp = -0.5 * (c / b_2)
	return tmp
function code(a, b_2, c)
	tmp = 0.0
	if (b_2 <= -5e-310)
		tmp = Float64(-2.0 * Float64(b_2 / a));
	else
		tmp = Float64(-0.5 * Float64(c / b_2));
	end
	return tmp
end
function tmp_2 = code(a, b_2, c)
	tmp = 0.0;
	if (b_2 <= -5e-310)
		tmp = -2.0 * (b_2 / a);
	else
		tmp = -0.5 * (c / b_2);
	end
	tmp_2 = tmp;
end
code[a_, b$95$2_, c_] := If[LessEqual[b$95$2, -5e-310], N[(-2.0 * N[(b$95$2 / a), $MachinePrecision]), $MachinePrecision], N[(-0.5 * N[(c / b$95$2), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;b\_2 \leq -5 \cdot 10^{-310}:\\
\;\;\;\;-2 \cdot \frac{b\_2}{a}\\

\mathbf{else}:\\
\;\;\;\;-0.5 \cdot \frac{c}{b\_2}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if b_2 < -4.999999999999985e-310

    1. Initial program 72.6%

      \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
    2. Add Preprocessing
    3. Taylor expanded in b_2 around -inf 71.4%

      \[\leadsto \color{blue}{-2 \cdot \frac{b\_2}{a}} \]

    if -4.999999999999985e-310 < b_2

    1. Initial program 32.9%

      \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
    2. Add Preprocessing
    3. Taylor expanded in b_2 around inf 66.8%

      \[\leadsto \color{blue}{-0.5 \cdot \frac{c}{b\_2}} \]
  3. Recombined 2 regimes into one program.
  4. Add Preprocessing

Alternative 5: 35.1% accurate, 22.4× speedup?

\[\begin{array}{l} \\ -2 \cdot \frac{b\_2}{a} \end{array} \]
(FPCore (a b_2 c) :precision binary64 (* -2.0 (/ b_2 a)))
double code(double a, double b_2, double c) {
	return -2.0 * (b_2 / a);
}
real(8) function code(a, b_2, c)
    real(8), intent (in) :: a
    real(8), intent (in) :: b_2
    real(8), intent (in) :: c
    code = (-2.0d0) * (b_2 / a)
end function
public static double code(double a, double b_2, double c) {
	return -2.0 * (b_2 / a);
}
def code(a, b_2, c):
	return -2.0 * (b_2 / a)
function code(a, b_2, c)
	return Float64(-2.0 * Float64(b_2 / a))
end
function tmp = code(a, b_2, c)
	tmp = -2.0 * (b_2 / a);
end
code[a_, b$95$2_, c_] := N[(-2.0 * N[(b$95$2 / a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
-2 \cdot \frac{b\_2}{a}
\end{array}
Derivation
  1. Initial program 51.2%

    \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
  2. Add Preprocessing
  3. Taylor expanded in b_2 around -inf 34.3%

    \[\leadsto \color{blue}{-2 \cdot \frac{b\_2}{a}} \]
  4. Add Preprocessing

Alternative 6: 15.2% accurate, 28.0× speedup?

\[\begin{array}{l} \\ \frac{-b\_2}{a} \end{array} \]
(FPCore (a b_2 c) :precision binary64 (/ (- b_2) a))
double code(double a, double b_2, double c) {
	return -b_2 / a;
}
real(8) function code(a, b_2, c)
    real(8), intent (in) :: a
    real(8), intent (in) :: b_2
    real(8), intent (in) :: c
    code = -b_2 / a
end function
public static double code(double a, double b_2, double c) {
	return -b_2 / a;
}
def code(a, b_2, c):
	return -b_2 / a
function code(a, b_2, c)
	return Float64(Float64(-b_2) / a)
end
function tmp = code(a, b_2, c)
	tmp = -b_2 / a;
end
code[a_, b$95$2_, c_] := N[((-b$95$2) / a), $MachinePrecision]
\begin{array}{l}

\\
\frac{-b\_2}{a}
\end{array}
Derivation
  1. Initial program 51.2%

    \[\frac{\left(-b\_2\right) + \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a} \]
  2. Add Preprocessing
  3. Taylor expanded in b_2 around 0 32.9%

    \[\leadsto \frac{\left(-b\_2\right) + \sqrt{\color{blue}{-1 \cdot \left(a \cdot c\right)}}}{a} \]
  4. Step-by-step derivation
    1. mul-1-neg32.9%

      \[\leadsto \frac{\left(-b\_2\right) + \sqrt{\color{blue}{-a \cdot c}}}{a} \]
  5. Simplified32.9%

    \[\leadsto \frac{\left(-b\_2\right) + \sqrt{\color{blue}{-a \cdot c}}}{a} \]
  6. Taylor expanded in b_2 around inf 15.6%

    \[\leadsto \frac{\color{blue}{-1 \cdot b\_2}}{a} \]
  7. Step-by-step derivation
    1. mul-1-neg15.6%

      \[\leadsto \frac{\color{blue}{-b\_2}}{a} \]
  8. Simplified15.6%

    \[\leadsto \frac{\color{blue}{-b\_2}}{a} \]
  9. Add Preprocessing

Developer target: 99.6% accurate, 0.1× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \sqrt{\left|a\right|} \cdot \sqrt{\left|c\right|}\\ t_1 := \begin{array}{l} \mathbf{if}\;\mathsf{copysign}\left(a, c\right) = a:\\ \;\;\;\;\sqrt{\left|b\_2\right| - t\_0} \cdot \sqrt{\left|b\_2\right| + t\_0}\\ \mathbf{else}:\\ \;\;\;\;\mathsf{hypot}\left(b\_2, t\_0\right)\\ \end{array}\\ \mathbf{if}\;b\_2 < 0:\\ \;\;\;\;\frac{t\_1 - b\_2}{a}\\ \mathbf{else}:\\ \;\;\;\;\frac{-c}{b\_2 + t\_1}\\ \end{array} \end{array} \]
(FPCore (a b_2 c)
 :precision binary64
 (let* ((t_0 (* (sqrt (fabs a)) (sqrt (fabs c))))
        (t_1
         (if (== (copysign a c) a)
           (* (sqrt (- (fabs b_2) t_0)) (sqrt (+ (fabs b_2) t_0)))
           (hypot b_2 t_0))))
   (if (< b_2 0.0) (/ (- t_1 b_2) a) (/ (- c) (+ b_2 t_1)))))
double code(double a, double b_2, double c) {
	double t_0 = sqrt(fabs(a)) * sqrt(fabs(c));
	double tmp;
	if (copysign(a, c) == a) {
		tmp = sqrt((fabs(b_2) - t_0)) * sqrt((fabs(b_2) + t_0));
	} else {
		tmp = hypot(b_2, t_0);
	}
	double t_1 = tmp;
	double tmp_1;
	if (b_2 < 0.0) {
		tmp_1 = (t_1 - b_2) / a;
	} else {
		tmp_1 = -c / (b_2 + t_1);
	}
	return tmp_1;
}
public static double code(double a, double b_2, double c) {
	double t_0 = Math.sqrt(Math.abs(a)) * Math.sqrt(Math.abs(c));
	double tmp;
	if (Math.copySign(a, c) == a) {
		tmp = Math.sqrt((Math.abs(b_2) - t_0)) * Math.sqrt((Math.abs(b_2) + t_0));
	} else {
		tmp = Math.hypot(b_2, t_0);
	}
	double t_1 = tmp;
	double tmp_1;
	if (b_2 < 0.0) {
		tmp_1 = (t_1 - b_2) / a;
	} else {
		tmp_1 = -c / (b_2 + t_1);
	}
	return tmp_1;
}
def code(a, b_2, c):
	t_0 = math.sqrt(math.fabs(a)) * math.sqrt(math.fabs(c))
	tmp = 0
	if math.copysign(a, c) == a:
		tmp = math.sqrt((math.fabs(b_2) - t_0)) * math.sqrt((math.fabs(b_2) + t_0))
	else:
		tmp = math.hypot(b_2, t_0)
	t_1 = tmp
	tmp_1 = 0
	if b_2 < 0.0:
		tmp_1 = (t_1 - b_2) / a
	else:
		tmp_1 = -c / (b_2 + t_1)
	return tmp_1
function code(a, b_2, c)
	t_0 = Float64(sqrt(abs(a)) * sqrt(abs(c)))
	tmp = 0.0
	if (copysign(a, c) == a)
		tmp = Float64(sqrt(Float64(abs(b_2) - t_0)) * sqrt(Float64(abs(b_2) + t_0)));
	else
		tmp = hypot(b_2, t_0);
	end
	t_1 = tmp
	tmp_1 = 0.0
	if (b_2 < 0.0)
		tmp_1 = Float64(Float64(t_1 - b_2) / a);
	else
		tmp_1 = Float64(Float64(-c) / Float64(b_2 + t_1));
	end
	return tmp_1
end
function tmp_3 = code(a, b_2, c)
	t_0 = sqrt(abs(a)) * sqrt(abs(c));
	tmp = 0.0;
	if ((sign(c) * abs(a)) == a)
		tmp = sqrt((abs(b_2) - t_0)) * sqrt((abs(b_2) + t_0));
	else
		tmp = hypot(b_2, t_0);
	end
	t_1 = tmp;
	tmp_2 = 0.0;
	if (b_2 < 0.0)
		tmp_2 = (t_1 - b_2) / a;
	else
		tmp_2 = -c / (b_2 + t_1);
	end
	tmp_3 = tmp_2;
end
code[a_, b$95$2_, c_] := Block[{t$95$0 = N[(N[Sqrt[N[Abs[a], $MachinePrecision]], $MachinePrecision] * N[Sqrt[N[Abs[c], $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, Block[{t$95$1 = If[Equal[N[With[{TMP1 = Abs[a], TMP2 = Sign[c]}, TMP1 * If[TMP2 == 0, 1, TMP2]], $MachinePrecision], a], N[(N[Sqrt[N[(N[Abs[b$95$2], $MachinePrecision] - t$95$0), $MachinePrecision]], $MachinePrecision] * N[Sqrt[N[(N[Abs[b$95$2], $MachinePrecision] + t$95$0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision], N[Sqrt[b$95$2 ^ 2 + t$95$0 ^ 2], $MachinePrecision]]}, If[Less[b$95$2, 0.0], N[(N[(t$95$1 - b$95$2), $MachinePrecision] / a), $MachinePrecision], N[((-c) / N[(b$95$2 + t$95$1), $MachinePrecision]), $MachinePrecision]]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \sqrt{\left|a\right|} \cdot \sqrt{\left|c\right|}\\
t_1 := \begin{array}{l}
\mathbf{if}\;\mathsf{copysign}\left(a, c\right) = a:\\
\;\;\;\;\sqrt{\left|b\_2\right| - t\_0} \cdot \sqrt{\left|b\_2\right| + t\_0}\\

\mathbf{else}:\\
\;\;\;\;\mathsf{hypot}\left(b\_2, t\_0\right)\\


\end{array}\\
\mathbf{if}\;b\_2 < 0:\\
\;\;\;\;\frac{t\_1 - b\_2}{a}\\

\mathbf{else}:\\
\;\;\;\;\frac{-c}{b\_2 + t\_1}\\


\end{array}
\end{array}

Reproduce

?
herbie shell --seed 2024095 
(FPCore (a b_2 c)
  :name "quad2p (problem 3.2.1, positive)"
  :precision binary64
  :herbie-expected 10

  :alt
  (if (< b_2 0.0) (/ (- (if (== (copysign a c) a) (* (sqrt (- (fabs b_2) (* (sqrt (fabs a)) (sqrt (fabs c))))) (sqrt (+ (fabs b_2) (* (sqrt (fabs a)) (sqrt (fabs c)))))) (hypot b_2 (* (sqrt (fabs a)) (sqrt (fabs c))))) b_2) a) (/ (- c) (+ b_2 (if (== (copysign a c) a) (* (sqrt (- (fabs b_2) (* (sqrt (fabs a)) (sqrt (fabs c))))) (sqrt (+ (fabs b_2) (* (sqrt (fabs a)) (sqrt (fabs c)))))) (hypot b_2 (* (sqrt (fabs a)) (sqrt (fabs c))))))))

  (/ (+ (- b_2) (sqrt (- (* b_2 b_2) (* a c)))) a))