1/2(abs(p)+abs(r) - sqrt((p-r)^2 + 4q^2))

Percentage Accurate: 24.1% → 58.5%
Time: 8.0s
Alternatives: 3
Speedup: 83.3×

Specification

?
\[\begin{array}{l} \\ \frac{1}{2} \cdot \left(\left(\left|p\right| + \left|r\right|\right) - \sqrt{{\left(p - r\right)}^{2} + 4 \cdot {q}^{2}}\right) \end{array} \]
(FPCore (p r q)
 :precision binary64
 (*
  (/ 1.0 2.0)
  (- (+ (fabs p) (fabs r)) (sqrt (+ (pow (- p r) 2.0) (* 4.0 (pow q 2.0)))))))
double code(double p, double r, double q) {
	return (1.0 / 2.0) * ((fabs(p) + fabs(r)) - sqrt((pow((p - r), 2.0) + (4.0 * pow(q, 2.0)))));
}
real(8) function code(p, r, q)
    real(8), intent (in) :: p
    real(8), intent (in) :: r
    real(8), intent (in) :: q
    code = (1.0d0 / 2.0d0) * ((abs(p) + abs(r)) - sqrt((((p - r) ** 2.0d0) + (4.0d0 * (q ** 2.0d0)))))
end function
public static double code(double p, double r, double q) {
	return (1.0 / 2.0) * ((Math.abs(p) + Math.abs(r)) - Math.sqrt((Math.pow((p - r), 2.0) + (4.0 * Math.pow(q, 2.0)))));
}
def code(p, r, q):
	return (1.0 / 2.0) * ((math.fabs(p) + math.fabs(r)) - math.sqrt((math.pow((p - r), 2.0) + (4.0 * math.pow(q, 2.0)))))
function code(p, r, q)
	return Float64(Float64(1.0 / 2.0) * Float64(Float64(abs(p) + abs(r)) - sqrt(Float64((Float64(p - r) ^ 2.0) + Float64(4.0 * (q ^ 2.0))))))
end
function tmp = code(p, r, q)
	tmp = (1.0 / 2.0) * ((abs(p) + abs(r)) - sqrt((((p - r) ^ 2.0) + (4.0 * (q ^ 2.0)))));
end
code[p_, r_, q_] := N[(N[(1.0 / 2.0), $MachinePrecision] * N[(N[(N[Abs[p], $MachinePrecision] + N[Abs[r], $MachinePrecision]), $MachinePrecision] - N[Sqrt[N[(N[Power[N[(p - r), $MachinePrecision], 2.0], $MachinePrecision] + N[(4.0 * N[Power[q, 2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{1}{2} \cdot \left(\left(\left|p\right| + \left|r\right|\right) - \sqrt{{\left(p - r\right)}^{2} + 4 \cdot {q}^{2}}\right)
\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 3 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: 24.1% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \frac{1}{2} \cdot \left(\left(\left|p\right| + \left|r\right|\right) - \sqrt{{\left(p - r\right)}^{2} + 4 \cdot {q}^{2}}\right) \end{array} \]
(FPCore (p r q)
 :precision binary64
 (*
  (/ 1.0 2.0)
  (- (+ (fabs p) (fabs r)) (sqrt (+ (pow (- p r) 2.0) (* 4.0 (pow q 2.0)))))))
double code(double p, double r, double q) {
	return (1.0 / 2.0) * ((fabs(p) + fabs(r)) - sqrt((pow((p - r), 2.0) + (4.0 * pow(q, 2.0)))));
}
real(8) function code(p, r, q)
    real(8), intent (in) :: p
    real(8), intent (in) :: r
    real(8), intent (in) :: q
    code = (1.0d0 / 2.0d0) * ((abs(p) + abs(r)) - sqrt((((p - r) ** 2.0d0) + (4.0d0 * (q ** 2.0d0)))))
end function
public static double code(double p, double r, double q) {
	return (1.0 / 2.0) * ((Math.abs(p) + Math.abs(r)) - Math.sqrt((Math.pow((p - r), 2.0) + (4.0 * Math.pow(q, 2.0)))));
}
def code(p, r, q):
	return (1.0 / 2.0) * ((math.fabs(p) + math.fabs(r)) - math.sqrt((math.pow((p - r), 2.0) + (4.0 * math.pow(q, 2.0)))))
function code(p, r, q)
	return Float64(Float64(1.0 / 2.0) * Float64(Float64(abs(p) + abs(r)) - sqrt(Float64((Float64(p - r) ^ 2.0) + Float64(4.0 * (q ^ 2.0))))))
end
function tmp = code(p, r, q)
	tmp = (1.0 / 2.0) * ((abs(p) + abs(r)) - sqrt((((p - r) ^ 2.0) + (4.0 * (q ^ 2.0)))));
end
code[p_, r_, q_] := N[(N[(1.0 / 2.0), $MachinePrecision] * N[(N[(N[Abs[p], $MachinePrecision] + N[Abs[r], $MachinePrecision]), $MachinePrecision] - N[Sqrt[N[(N[Power[N[(p - r), $MachinePrecision], 2.0], $MachinePrecision] + N[(4.0 * N[Power[q, 2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{1}{2} \cdot \left(\left(\left|p\right| + \left|r\right|\right) - \sqrt{{\left(p - r\right)}^{2} + 4 \cdot {q}^{2}}\right)
\end{array}

Alternative 1: 58.5% accurate, 2.0× speedup?

\[\begin{array}{l} q_m = \left|q\right| \\ [p, r, q_m] = \mathsf{sort}([p, r, q_m])\\ \\ \begin{array}{l} \mathbf{if}\;{q\_m}^{2} \leq 10^{-15}:\\ \;\;\;\;0.5 \cdot \left(\left(p + \left(\left|r\right| - r\right)\right) + \left|p\right|\right)\\ \mathbf{else}:\\ \;\;\;\;-q\_m\\ \end{array} \end{array} \]
q_m = (fabs.f64 q)
NOTE: p, r, and q_m should be sorted in increasing order before calling this function.
(FPCore (p r q_m)
 :precision binary64
 (if (<= (pow q_m 2.0) 1e-15)
   (* 0.5 (+ (+ p (- (fabs r) r)) (fabs p)))
   (- q_m)))
q_m = fabs(q);
assert(p < r && r < q_m);
double code(double p, double r, double q_m) {
	double tmp;
	if (pow(q_m, 2.0) <= 1e-15) {
		tmp = 0.5 * ((p + (fabs(r) - r)) + fabs(p));
	} else {
		tmp = -q_m;
	}
	return tmp;
}
q_m = abs(q)
NOTE: p, r, and q_m should be sorted in increasing order before calling this function.
real(8) function code(p, r, q_m)
    real(8), intent (in) :: p
    real(8), intent (in) :: r
    real(8), intent (in) :: q_m
    real(8) :: tmp
    if ((q_m ** 2.0d0) <= 1d-15) then
        tmp = 0.5d0 * ((p + (abs(r) - r)) + abs(p))
    else
        tmp = -q_m
    end if
    code = tmp
end function
q_m = Math.abs(q);
assert p < r && r < q_m;
public static double code(double p, double r, double q_m) {
	double tmp;
	if (Math.pow(q_m, 2.0) <= 1e-15) {
		tmp = 0.5 * ((p + (Math.abs(r) - r)) + Math.abs(p));
	} else {
		tmp = -q_m;
	}
	return tmp;
}
q_m = math.fabs(q)
[p, r, q_m] = sort([p, r, q_m])
def code(p, r, q_m):
	tmp = 0
	if math.pow(q_m, 2.0) <= 1e-15:
		tmp = 0.5 * ((p + (math.fabs(r) - r)) + math.fabs(p))
	else:
		tmp = -q_m
	return tmp
q_m = abs(q)
p, r, q_m = sort([p, r, q_m])
function code(p, r, q_m)
	tmp = 0.0
	if ((q_m ^ 2.0) <= 1e-15)
		tmp = Float64(0.5 * Float64(Float64(p + Float64(abs(r) - r)) + abs(p)));
	else
		tmp = Float64(-q_m);
	end
	return tmp
end
q_m = abs(q);
p, r, q_m = num2cell(sort([p, r, q_m])){:}
function tmp_2 = code(p, r, q_m)
	tmp = 0.0;
	if ((q_m ^ 2.0) <= 1e-15)
		tmp = 0.5 * ((p + (abs(r) - r)) + abs(p));
	else
		tmp = -q_m;
	end
	tmp_2 = tmp;
end
q_m = N[Abs[q], $MachinePrecision]
NOTE: p, r, and q_m should be sorted in increasing order before calling this function.
code[p_, r_, q$95$m_] := If[LessEqual[N[Power[q$95$m, 2.0], $MachinePrecision], 1e-15], N[(0.5 * N[(N[(p + N[(N[Abs[r], $MachinePrecision] - r), $MachinePrecision]), $MachinePrecision] + N[Abs[p], $MachinePrecision]), $MachinePrecision]), $MachinePrecision], (-q$95$m)]
\begin{array}{l}
q_m = \left|q\right|
\\
[p, r, q_m] = \mathsf{sort}([p, r, q_m])\\
\\
\begin{array}{l}
\mathbf{if}\;{q\_m}^{2} \leq 10^{-15}:\\
\;\;\;\;0.5 \cdot \left(\left(p + \left(\left|r\right| - r\right)\right) + \left|p\right|\right)\\

\mathbf{else}:\\
\;\;\;\;-q\_m\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (pow.f64 q #s(literal 2 binary64)) < 1.0000000000000001e-15

    1. Initial program 20.3%

      \[\frac{1}{2} \cdot \left(\left(\left|p\right| + \left|r\right|\right) - \sqrt{{\left(p - r\right)}^{2} + 4 \cdot {q}^{2}}\right) \]
    2. Add Preprocessing
    3. Taylor expanded in p around -inf

      \[\leadsto \color{blue}{-1 \cdot \left(p \cdot \left(\frac{-1}{2} \cdot \frac{\left(\left|p\right| + \left|r\right|\right) - r}{p} - \frac{1}{2}\right)\right)} \]
    4. Step-by-step derivation
      1. associate-*r*N/A

        \[\leadsto \color{blue}{\left(-1 \cdot p\right) \cdot \left(\frac{-1}{2} \cdot \frac{\left(\left|p\right| + \left|r\right|\right) - r}{p} - \frac{1}{2}\right)} \]
      2. mul-1-negN/A

        \[\leadsto \color{blue}{\left(\mathsf{neg}\left(p\right)\right)} \cdot \left(\frac{-1}{2} \cdot \frac{\left(\left|p\right| + \left|r\right|\right) - r}{p} - \frac{1}{2}\right) \]
      3. lower-*.f64N/A

        \[\leadsto \color{blue}{\left(\mathsf{neg}\left(p\right)\right) \cdot \left(\frac{-1}{2} \cdot \frac{\left(\left|p\right| + \left|r\right|\right) - r}{p} - \frac{1}{2}\right)} \]
      4. lower-neg.f64N/A

        \[\leadsto \color{blue}{\left(-p\right)} \cdot \left(\frac{-1}{2} \cdot \frac{\left(\left|p\right| + \left|r\right|\right) - r}{p} - \frac{1}{2}\right) \]
      5. sub-negN/A

        \[\leadsto \left(-p\right) \cdot \color{blue}{\left(\frac{-1}{2} \cdot \frac{\left(\left|p\right| + \left|r\right|\right) - r}{p} + \left(\mathsf{neg}\left(\frac{1}{2}\right)\right)\right)} \]
      6. *-commutativeN/A

        \[\leadsto \left(-p\right) \cdot \left(\color{blue}{\frac{\left(\left|p\right| + \left|r\right|\right) - r}{p} \cdot \frac{-1}{2}} + \left(\mathsf{neg}\left(\frac{1}{2}\right)\right)\right) \]
      7. metadata-evalN/A

        \[\leadsto \left(-p\right) \cdot \left(\frac{\left(\left|p\right| + \left|r\right|\right) - r}{p} \cdot \frac{-1}{2} + \color{blue}{\frac{-1}{2}}\right) \]
      8. lower-fma.f64N/A

        \[\leadsto \left(-p\right) \cdot \color{blue}{\mathsf{fma}\left(\frac{\left(\left|p\right| + \left|r\right|\right) - r}{p}, \frac{-1}{2}, \frac{-1}{2}\right)} \]
      9. lower-/.f64N/A

        \[\leadsto \left(-p\right) \cdot \mathsf{fma}\left(\color{blue}{\frac{\left(\left|p\right| + \left|r\right|\right) - r}{p}}, \frac{-1}{2}, \frac{-1}{2}\right) \]
      10. lower--.f64N/A

        \[\leadsto \left(-p\right) \cdot \mathsf{fma}\left(\frac{\color{blue}{\left(\left|p\right| + \left|r\right|\right) - r}}{p}, \frac{-1}{2}, \frac{-1}{2}\right) \]
      11. +-commutativeN/A

        \[\leadsto \left(-p\right) \cdot \mathsf{fma}\left(\frac{\color{blue}{\left(\left|r\right| + \left|p\right|\right)} - r}{p}, \frac{-1}{2}, \frac{-1}{2}\right) \]
      12. lower-+.f64N/A

        \[\leadsto \left(-p\right) \cdot \mathsf{fma}\left(\frac{\color{blue}{\left(\left|r\right| + \left|p\right|\right)} - r}{p}, \frac{-1}{2}, \frac{-1}{2}\right) \]
      13. lower-fabs.f64N/A

        \[\leadsto \left(-p\right) \cdot \mathsf{fma}\left(\frac{\left(\color{blue}{\left|r\right|} + \left|p\right|\right) - r}{p}, \frac{-1}{2}, \frac{-1}{2}\right) \]
      14. lower-fabs.f6410.5

        \[\leadsto \left(-p\right) \cdot \mathsf{fma}\left(\frac{\left(\left|r\right| + \color{blue}{\left|p\right|}\right) - r}{p}, -0.5, -0.5\right) \]
    5. Applied rewrites10.5%

      \[\leadsto \color{blue}{\left(-p\right) \cdot \mathsf{fma}\left(\frac{\left(\left|r\right| + \left|p\right|\right) - r}{p}, -0.5, -0.5\right)} \]
    6. Taylor expanded in p around 0

      \[\leadsto \frac{1}{2} \cdot p + \color{blue}{\frac{1}{2} \cdot \left(\left(\left|p\right| + \left|r\right|\right) - r\right)} \]
    7. Step-by-step derivation
      1. Applied rewrites27.8%

        \[\leadsto 0.5 \cdot \color{blue}{\left(\left(p + \left(\left|r\right| - r\right)\right) + \left|p\right|\right)} \]

      if 1.0000000000000001e-15 < (pow.f64 q #s(literal 2 binary64))

      1. Initial program 26.3%

        \[\frac{1}{2} \cdot \left(\left(\left|p\right| + \left|r\right|\right) - \sqrt{{\left(p - r\right)}^{2} + 4 \cdot {q}^{2}}\right) \]
      2. Add Preprocessing
      3. Taylor expanded in q around inf

        \[\leadsto \color{blue}{-1 \cdot q} \]
      4. Step-by-step derivation
        1. mul-1-negN/A

          \[\leadsto \color{blue}{\mathsf{neg}\left(q\right)} \]
        2. lower-neg.f6433.0

          \[\leadsto \color{blue}{-q} \]
      5. Applied rewrites33.0%

        \[\leadsto \color{blue}{-q} \]
    8. Recombined 2 regimes into one program.
    9. Add Preprocessing

    Alternative 2: 41.3% accurate, 2.0× speedup?

    \[\begin{array}{l} q_m = \left|q\right| \\ [p, r, q_m] = \mathsf{sort}([p, r, q_m])\\ \\ \begin{array}{l} \mathbf{if}\;{q\_m}^{2} \leq 10^{-290}:\\ \;\;\;\;\left(\left(p + \left|r\right|\right) + \left|p\right|\right) \cdot 0.5\\ \mathbf{else}:\\ \;\;\;\;-q\_m\\ \end{array} \end{array} \]
    q_m = (fabs.f64 q)
    NOTE: p, r, and q_m should be sorted in increasing order before calling this function.
    (FPCore (p r q_m)
     :precision binary64
     (if (<= (pow q_m 2.0) 1e-290) (* (+ (+ p (fabs r)) (fabs p)) 0.5) (- q_m)))
    q_m = fabs(q);
    assert(p < r && r < q_m);
    double code(double p, double r, double q_m) {
    	double tmp;
    	if (pow(q_m, 2.0) <= 1e-290) {
    		tmp = ((p + fabs(r)) + fabs(p)) * 0.5;
    	} else {
    		tmp = -q_m;
    	}
    	return tmp;
    }
    
    q_m = abs(q)
    NOTE: p, r, and q_m should be sorted in increasing order before calling this function.
    real(8) function code(p, r, q_m)
        real(8), intent (in) :: p
        real(8), intent (in) :: r
        real(8), intent (in) :: q_m
        real(8) :: tmp
        if ((q_m ** 2.0d0) <= 1d-290) then
            tmp = ((p + abs(r)) + abs(p)) * 0.5d0
        else
            tmp = -q_m
        end if
        code = tmp
    end function
    
    q_m = Math.abs(q);
    assert p < r && r < q_m;
    public static double code(double p, double r, double q_m) {
    	double tmp;
    	if (Math.pow(q_m, 2.0) <= 1e-290) {
    		tmp = ((p + Math.abs(r)) + Math.abs(p)) * 0.5;
    	} else {
    		tmp = -q_m;
    	}
    	return tmp;
    }
    
    q_m = math.fabs(q)
    [p, r, q_m] = sort([p, r, q_m])
    def code(p, r, q_m):
    	tmp = 0
    	if math.pow(q_m, 2.0) <= 1e-290:
    		tmp = ((p + math.fabs(r)) + math.fabs(p)) * 0.5
    	else:
    		tmp = -q_m
    	return tmp
    
    q_m = abs(q)
    p, r, q_m = sort([p, r, q_m])
    function code(p, r, q_m)
    	tmp = 0.0
    	if ((q_m ^ 2.0) <= 1e-290)
    		tmp = Float64(Float64(Float64(p + abs(r)) + abs(p)) * 0.5);
    	else
    		tmp = Float64(-q_m);
    	end
    	return tmp
    end
    
    q_m = abs(q);
    p, r, q_m = num2cell(sort([p, r, q_m])){:}
    function tmp_2 = code(p, r, q_m)
    	tmp = 0.0;
    	if ((q_m ^ 2.0) <= 1e-290)
    		tmp = ((p + abs(r)) + abs(p)) * 0.5;
    	else
    		tmp = -q_m;
    	end
    	tmp_2 = tmp;
    end
    
    q_m = N[Abs[q], $MachinePrecision]
    NOTE: p, r, and q_m should be sorted in increasing order before calling this function.
    code[p_, r_, q$95$m_] := If[LessEqual[N[Power[q$95$m, 2.0], $MachinePrecision], 1e-290], N[(N[(N[(p + N[Abs[r], $MachinePrecision]), $MachinePrecision] + N[Abs[p], $MachinePrecision]), $MachinePrecision] * 0.5), $MachinePrecision], (-q$95$m)]
    
    \begin{array}{l}
    q_m = \left|q\right|
    \\
    [p, r, q_m] = \mathsf{sort}([p, r, q_m])\\
    \\
    \begin{array}{l}
    \mathbf{if}\;{q\_m}^{2} \leq 10^{-290}:\\
    \;\;\;\;\left(\left(p + \left|r\right|\right) + \left|p\right|\right) \cdot 0.5\\
    
    \mathbf{else}:\\
    \;\;\;\;-q\_m\\
    
    
    \end{array}
    \end{array}
    
    Derivation
    1. Split input into 2 regimes
    2. if (pow.f64 q #s(literal 2 binary64)) < 1.0000000000000001e-290

      1. Initial program 22.5%

        \[\frac{1}{2} \cdot \left(\left(\left|p\right| + \left|r\right|\right) - \sqrt{{\left(p - r\right)}^{2} + 4 \cdot {q}^{2}}\right) \]
      2. Add Preprocessing
      3. Taylor expanded in q around inf

        \[\leadsto \color{blue}{-1 \cdot q} \]
      4. Step-by-step derivation
        1. mul-1-negN/A

          \[\leadsto \color{blue}{\mathsf{neg}\left(q\right)} \]
        2. lower-neg.f6410.0

          \[\leadsto \color{blue}{-q} \]
      5. Applied rewrites10.0%

        \[\leadsto \color{blue}{-q} \]
      6. Taylor expanded in r around inf

        \[\leadsto \color{blue}{r \cdot \left(\frac{1}{2} \cdot \frac{\left(\left|p\right| + \left|r\right|\right) - -1 \cdot p}{r} - \frac{1}{2}\right)} \]
      7. Step-by-step derivation
        1. *-commutativeN/A

          \[\leadsto \color{blue}{\left(\frac{1}{2} \cdot \frac{\left(\left|p\right| + \left|r\right|\right) - -1 \cdot p}{r} - \frac{1}{2}\right) \cdot r} \]
        2. cancel-sign-sub-invN/A

          \[\leadsto \left(\frac{1}{2} \cdot \frac{\color{blue}{\left(\left|p\right| + \left|r\right|\right) + \left(\mathsf{neg}\left(-1\right)\right) \cdot p}}{r} - \frac{1}{2}\right) \cdot r \]
        3. metadata-evalN/A

          \[\leadsto \left(\frac{1}{2} \cdot \frac{\left(\left|p\right| + \left|r\right|\right) + \color{blue}{1} \cdot p}{r} - \frac{1}{2}\right) \cdot r \]
        4. *-lft-identityN/A

          \[\leadsto \left(\frac{1}{2} \cdot \frac{\left(\left|p\right| + \left|r\right|\right) + \color{blue}{p}}{r} - \frac{1}{2}\right) \cdot r \]
        5. +-commutativeN/A

          \[\leadsto \left(\frac{1}{2} \cdot \frac{\color{blue}{p + \left(\left|p\right| + \left|r\right|\right)}}{r} - \frac{1}{2}\right) \cdot r \]
      8. Applied rewrites5.8%

        \[\leadsto \color{blue}{\mathsf{fma}\left(\left(p + \left|r\right|\right) + \left|p\right|, \frac{0.5}{r}, -0.5\right) \cdot r} \]
      9. Taylor expanded in r around 0

        \[\leadsto \frac{1}{2} \cdot \color{blue}{\left(p + \left(\left|p\right| + \left|r\right|\right)\right)} \]
      10. Step-by-step derivation
        1. Applied rewrites10.5%

          \[\leadsto \left(\left(p + \left|r\right|\right) + \left|p\right|\right) \cdot \color{blue}{0.5} \]

        if 1.0000000000000001e-290 < (pow.f64 q #s(literal 2 binary64))

        1. Initial program 23.8%

          \[\frac{1}{2} \cdot \left(\left(\left|p\right| + \left|r\right|\right) - \sqrt{{\left(p - r\right)}^{2} + 4 \cdot {q}^{2}}\right) \]
        2. Add Preprocessing
        3. Taylor expanded in q around inf

          \[\leadsto \color{blue}{-1 \cdot q} \]
        4. Step-by-step derivation
          1. mul-1-negN/A

            \[\leadsto \color{blue}{\mathsf{neg}\left(q\right)} \]
          2. lower-neg.f6428.4

            \[\leadsto \color{blue}{-q} \]
        5. Applied rewrites28.4%

          \[\leadsto \color{blue}{-q} \]
      11. Recombined 2 regimes into one program.
      12. Add Preprocessing

      Alternative 3: 36.7% accurate, 83.3× speedup?

      \[\begin{array}{l} q_m = \left|q\right| \\ [p, r, q_m] = \mathsf{sort}([p, r, q_m])\\ \\ -q\_m \end{array} \]
      q_m = (fabs.f64 q)
      NOTE: p, r, and q_m should be sorted in increasing order before calling this function.
      (FPCore (p r q_m) :precision binary64 (- q_m))
      q_m = fabs(q);
      assert(p < r && r < q_m);
      double code(double p, double r, double q_m) {
      	return -q_m;
      }
      
      q_m = abs(q)
      NOTE: p, r, and q_m should be sorted in increasing order before calling this function.
      real(8) function code(p, r, q_m)
          real(8), intent (in) :: p
          real(8), intent (in) :: r
          real(8), intent (in) :: q_m
          code = -q_m
      end function
      
      q_m = Math.abs(q);
      assert p < r && r < q_m;
      public static double code(double p, double r, double q_m) {
      	return -q_m;
      }
      
      q_m = math.fabs(q)
      [p, r, q_m] = sort([p, r, q_m])
      def code(p, r, q_m):
      	return -q_m
      
      q_m = abs(q)
      p, r, q_m = sort([p, r, q_m])
      function code(p, r, q_m)
      	return Float64(-q_m)
      end
      
      q_m = abs(q);
      p, r, q_m = num2cell(sort([p, r, q_m])){:}
      function tmp = code(p, r, q_m)
      	tmp = -q_m;
      end
      
      q_m = N[Abs[q], $MachinePrecision]
      NOTE: p, r, and q_m should be sorted in increasing order before calling this function.
      code[p_, r_, q$95$m_] := (-q$95$m)
      
      \begin{array}{l}
      q_m = \left|q\right|
      \\
      [p, r, q_m] = \mathsf{sort}([p, r, q_m])\\
      \\
      -q\_m
      \end{array}
      
      Derivation
      1. Initial program 23.5%

        \[\frac{1}{2} \cdot \left(\left(\left|p\right| + \left|r\right|\right) - \sqrt{{\left(p - r\right)}^{2} + 4 \cdot {q}^{2}}\right) \]
      2. Add Preprocessing
      3. Taylor expanded in q around inf

        \[\leadsto \color{blue}{-1 \cdot q} \]
      4. Step-by-step derivation
        1. mul-1-negN/A

          \[\leadsto \color{blue}{\mathsf{neg}\left(q\right)} \]
        2. lower-neg.f6423.4

          \[\leadsto \color{blue}{-q} \]
      5. Applied rewrites23.4%

        \[\leadsto \color{blue}{-q} \]
      6. Add Preprocessing

      Reproduce

      ?
      herbie shell --seed 2024303 
      (FPCore (p r q)
        :name "1/2(abs(p)+abs(r) - sqrt((p-r)^2 + 4q^2))"
        :precision binary64
        (* (/ 1.0 2.0) (- (+ (fabs p) (fabs r)) (sqrt (+ (pow (- p r) 2.0) (* 4.0 (pow q 2.0)))))))