Cubic critical, medium range

Average Error: 43.9 → 0.5

Time: 17.2s

Precision: binary64

Cost: 7872

\[\left(\left(1.1102230246251565 \cdot 10^{-16} < a \land a < 9007199254740992\right) \land \left(1.1102230246251565 \cdot 10^{-16} < b \land b < 9007199254740992\right)\right) \land \left(1.1102230246251565 \cdot 10^{-16} < c \land c < 9007199254740992\right)\]

Math

\[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]

↓

\[\frac{c \cdot \left(3 \cdot a\right)}{\frac{a \cdot -3}{\frac{1}{b + \sqrt{b \cdot b + a \cdot \left(c \cdot -3\right)}}}} \]

FPCore

(FPCore (a b c)
 :precision binary64
 (/ (+ (- b) (sqrt (- (* b b) (* (* 3.0 a) c)))) (* 3.0 a)))

↓

(FPCore (a b c)
 :precision binary64
 (/
  (* c (* 3.0 a))
  (/ (* a -3.0) (/ 1.0 (+ b (sqrt (+ (* b b) (* a (* c -3.0)))))))))

C

double code(double a, double b, double c) {
	return (-b + sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a);
}

↓

double code(double a, double b, double c) {
	return (c * (3.0 * a)) / ((a * -3.0) / (1.0 / (b + sqrt(((b * b) + (a * (c * -3.0)))))));
}

Fortran

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

↓

real(8) function code(a, b, c)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    real(8), intent (in) :: c
    code = (c * (3.0d0 * a)) / ((a * (-3.0d0)) / (1.0d0 / (b + sqrt(((b * b) + (a * (c * (-3.0d0))))))))
end function

Java

public static double code(double a, double b, double c) {
	return (-b + Math.sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a);
}

↓

public static double code(double a, double b, double c) {
	return (c * (3.0 * a)) / ((a * -3.0) / (1.0 / (b + Math.sqrt(((b * b) + (a * (c * -3.0)))))));
}

Python

def code(a, b, c):
	return (-b + math.sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a)

↓

def code(a, b, c):
	return (c * (3.0 * a)) / ((a * -3.0) / (1.0 / (b + math.sqrt(((b * b) + (a * (c * -3.0)))))))

Julia

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 code(a, b, c)
	return Float64(Float64(c * Float64(3.0 * a)) / Float64(Float64(a * -3.0) / Float64(1.0 / Float64(b + sqrt(Float64(Float64(b * b) + Float64(a * Float64(c * -3.0))))))))
end

MATLAB

function tmp = code(a, b, c)
	tmp = (-b + sqrt(((b * b) - ((3.0 * a) * c)))) / (3.0 * a);
end

↓

function tmp = code(a, b, c)
	tmp = (c * (3.0 * a)) / ((a * -3.0) / (1.0 / (b + sqrt(((b * b) + (a * (c * -3.0)))))));
end

Wolfram

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]

↓

code[a_, b_, c_] := N[(N[(c * N[(3.0 * a), $MachinePrecision]), $MachinePrecision] / N[(N[(a * -3.0), $MachinePrecision] / N[(1.0 / N[(b + N[Sqrt[N[(N[(b * b), $MachinePrecision] + N[(a * N[(c * -3.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]

Derivation

1. Initial program 43.9

   \[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]

2. Simplified 43.9

   \[\leadsto \color{blue}{\left(b - \sqrt{\mathsf{fma}\left(a, c \cdot -3, b \cdot b\right)}\right) \cdot \frac{-0.3333333333333333}{a}} \]
   Proof

   [Start] 43.9	\[ \frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]
   remove-double-neg [<=] 43.9	\[ \frac{\left(-b\right) + \color{blue}{\left(-\left(-\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}\right)\right)}}{3 \cdot a} \]
   sub-neg [<=] 43.9	\[ \frac{\color{blue}{\left(-b\right) - \left(-\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}\right)}}{3 \cdot a} \]
   div-sub [=>] 44.2	\[ \color{blue}{\frac{-b}{3 \cdot a} - \frac{-\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}} \]
   neg-mul-1 [=>] 44.2	\[ \frac{\color{blue}{-1 \cdot b}}{3 \cdot a} - \frac{-\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]
   associate-*l/ [<=] 44.0	\[ \color{blue}{\frac{-1}{3 \cdot a} \cdot b} - \frac{-\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a} \]
   distribute-frac-neg [=>] 44.0	\[ \frac{-1}{3 \cdot a} \cdot b - \color{blue}{\left(-\frac{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}\right)} \]
   fma-neg [=>] 43.1	\[ \color{blue}{\mathsf{fma}\left(\frac{-1}{3 \cdot a}, b, -\left(-\frac{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}\right)\right)} \]
   /-rgt-identity [<=] 43.1	\[ \mathsf{fma}\left(\frac{-1}{3 \cdot a}, \color{blue}{\frac{b}{1}}, -\left(-\frac{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}\right)\right) \]
   metadata-eval [<=] 43.1	\[ \mathsf{fma}\left(\frac{-1}{3 \cdot a}, \frac{b}{\color{blue}{\frac{-1}{-1}}}, -\left(-\frac{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}\right)\right) \]
   associate-/l* [<=] 43.1	\[ \mathsf{fma}\left(\frac{-1}{3 \cdot a}, \color{blue}{\frac{b \cdot -1}{-1}}, -\left(-\frac{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}\right)\right) \]
   *-commutative [<=] 43.1	\[ \mathsf{fma}\left(\frac{-1}{3 \cdot a}, \frac{\color{blue}{-1 \cdot b}}{-1}, -\left(-\frac{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}\right)\right) \]
   neg-mul-1 [<=] 43.1	\[ \mathsf{fma}\left(\frac{-1}{3 \cdot a}, \frac{\color{blue}{-b}}{-1}, -\left(-\frac{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}\right)\right) \]
   fma-neg [<=] 44.0	\[ \color{blue}{\frac{-1}{3 \cdot a} \cdot \frac{-b}{-1} - \left(-\frac{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}\right)} \]
   neg-mul-1 [=>] 44.0	\[ \frac{-1}{3 \cdot a} \cdot \frac{-b}{-1} - \color{blue}{-1 \cdot \frac{\sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}} \]

3. Applied egg-rr 43.3

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

4. Taylor expanded in b around 0 0.6

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

5. Simplified 0.5

   \[\leadsto \frac{\color{blue}{c \cdot \left(3 \cdot a\right)}}{\frac{a \cdot -3}{\frac{1}{b + \sqrt{\mathsf{fma}\left(a, c \cdot -3, b \cdot b\right)}}}} \]
   Proof

   [Start] 0.6	\[ \frac{3 \cdot \left(c \cdot a\right)}{\frac{a \cdot -3}{\frac{1}{b + \sqrt{\mathsf{fma}\left(a, c \cdot -3, b \cdot b\right)}}}} \]
   *-commutative [=>] 0.6	\[ \frac{\color{blue}{\left(c \cdot a\right) \cdot 3}}{\frac{a \cdot -3}{\frac{1}{b + \sqrt{\mathsf{fma}\left(a, c \cdot -3, b \cdot b\right)}}}} \]
   associate-*l* [=>] 0.5	\[ \frac{\color{blue}{c \cdot \left(a \cdot 3\right)}}{\frac{a \cdot -3}{\frac{1}{b + \sqrt{\mathsf{fma}\left(a, c \cdot -3, b \cdot b\right)}}}} \]
   *-commutative [=>] 0.5	\[ \frac{c \cdot \color{blue}{\left(3 \cdot a\right)}}{\frac{a \cdot -3}{\frac{1}{b + \sqrt{\mathsf{fma}\left(a, c \cdot -3, b \cdot b\right)}}}} \]

6. Applied egg-rr 0.5

   \[\leadsto \frac{c \cdot \left(3 \cdot a\right)}{\frac{a \cdot -3}{\frac{1}{b + \sqrt{\color{blue}{b \cdot b + a \cdot \left(c \cdot -3\right)}}}}} \]

7. Final simplification 0.5

   \[\leadsto \frac{c \cdot \left(3 \cdot a\right)}{\frac{a \cdot -3}{\frac{1}{b + \sqrt{b \cdot b + a \cdot \left(c \cdot -3\right)}}}} \]

Alternatives

Alternative 1
Error	0.6
Cost	7872

\[\frac{3 \cdot \left(c \cdot a\right)}{\frac{a \cdot -3}{\frac{1}{b + \sqrt{b \cdot b + a \cdot \left(c \cdot -3\right)}}}} \]

Alternative 2
Error	5.9
Cost	7616

\[a \cdot \frac{c}{\frac{\mathsf{fma}\left(-6, a \cdot b, 4.5 \cdot \left(\frac{c}{b} \cdot \left(a \cdot a\right)\right)\right)}{3}} \]

Alternative 3
Error	6.0
Cost	7616

\[\left(3 \cdot a\right) \cdot \frac{c}{\mathsf{fma}\left(-6, a \cdot b, 4.5 \cdot \left(\frac{c}{b} \cdot \left(a \cdot a\right)\right)\right)} \]

Alternative 4
Error	6.0
Cost	1344

\[\frac{c \cdot \left(3 \cdot a\right)}{-6 \cdot \left(a \cdot b\right) + \frac{c \cdot 4.5}{\frac{b}{a \cdot a}}} \]

Alternative 5
Error	12.0
Cost	320

\[\frac{c}{b} \cdot -0.5 \]

Reproduce

herbie shell --seed 2023187 
(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)))