\[\frac{\left(-b\right) - \sqrt{{b}^2 - 4 \cdot \left(a \cdot c\right)}}{2 \cdot a}\]
Test:
The quadratic formula (r2)
Bits:
128 bits
Bits error versus a
Bits error versus b
Bits error versus c
Time: 14.8 s
Input Error: 18.1
Output Error: 2.4
Log:
Profile: 🕒
\(\begin{cases} \frac{c}{b} \cdot \frac{-2}{2} & \text{when } b \le -1.4516784f-11 \\ (\left(\sqrt{{b}^2 - \left(4 \cdot c\right) \cdot a}\right) * \left(\frac{\frac{-1}{2}}{a}\right) + \left(\frac{\frac{-1}{2}}{\frac{a}{b}}\right))_* & \text{when } b \le 3.318237f+16 \\ \frac{c}{b} - \frac{b}{a} & \text{otherwise} \end{cases}\)

    if b < -1.4516784f-11

    1. Started with
      \[\frac{\left(-b\right) - \sqrt{{b}^2 - 4 \cdot \left(a \cdot c\right)}}{2 \cdot a}\]
      28.2
    2. Applied taylor to get
      \[\frac{\left(-b\right) - \sqrt{{b}^2 - 4 \cdot \left(a \cdot c\right)}}{2 \cdot a} \leadsto \frac{-2 \cdot \frac{c \cdot a}{b}}{2 \cdot a}\]
      7.2
    3. Taylor expanded around -inf to get
      \[\frac{\color{red}{-2 \cdot \frac{c \cdot a}{b}}}{2 \cdot a} \leadsto \frac{\color{blue}{-2 \cdot \frac{c \cdot a}{b}}}{2 \cdot a}\]
      7.2
    4. Applied simplify to get
      \[\color{red}{\frac{-2 \cdot \frac{c \cdot a}{b}}{2 \cdot a}} \leadsto \color{blue}{\frac{c}{b} \cdot \frac{-2}{2}}\]
      0

    if -1.4516784f-11 < b < 3.318237f+16

    1. Started with
      \[\frac{\left(-b\right) - \sqrt{{b}^2 - 4 \cdot \left(a \cdot c\right)}}{2 \cdot a}\]
      5.4
    2. Using strategy rm
      5.4
    3. Applied add-cube-cbrt to get
      \[\color{red}{\frac{\left(-b\right) - \sqrt{{b}^2 - 4 \cdot \left(a \cdot c\right)}}{2 \cdot a}} \leadsto \color{blue}{{\left(\sqrt[3]{\frac{\left(-b\right) - \sqrt{{b}^2 - 4 \cdot \left(a \cdot c\right)}}{2 \cdot a}}\right)}^3}\]
      5.9
    4. Applied taylor to get
      \[{\left(\sqrt[3]{\frac{\left(-b\right) - \sqrt{{b}^2 - 4 \cdot \left(a \cdot c\right)}}{2 \cdot a}}\right)}^3 \leadsto {\left(\sqrt[3]{\frac{-1}{2} \cdot \left(\left(\frac{1}{b} + \sqrt{\frac{1}{{b}^2} - 4 \cdot \frac{1}{c \cdot a}}\right) \cdot a\right)}\right)}^3\]
      29.7
    5. Taylor expanded around inf to get
      \[{\color{red}{\left(\sqrt[3]{\frac{-1}{2} \cdot \left(\left(\frac{1}{b} + \sqrt{\frac{1}{{b}^2} - 4 \cdot \frac{1}{c \cdot a}}\right) \cdot a\right)}\right)}}^3 \leadsto {\color{blue}{\left(\sqrt[3]{\frac{-1}{2} \cdot \left(\left(\frac{1}{b} + \sqrt{\frac{1}{{b}^2} - 4 \cdot \frac{1}{c \cdot a}}\right) \cdot a\right)}\right)}}^3\]
      29.7
    6. Applied simplify to get
      \[\color{red}{{\left(\sqrt[3]{\frac{-1}{2} \cdot \left(\left(\frac{1}{b} + \sqrt{\frac{1}{{b}^2} - 4 \cdot \frac{1}{c \cdot a}}\right) \cdot a\right)}\right)}^3} \leadsto \color{blue}{(\left(\sqrt{\frac{1}{b \cdot b} - \frac{\frac{4}{a}}{c}}\right) * \left(\frac{-1}{2} \cdot a\right) + \left(\frac{a}{b} \cdot \frac{-1}{2}\right))_*}\]
      29.8
    7. Applied taylor to get
      \[(\left(\sqrt{\frac{1}{b \cdot b} - \frac{\frac{4}{a}}{c}}\right) * \left(\frac{-1}{2} \cdot a\right) + \left(\frac{a}{b} \cdot \frac{-1}{2}\right))_* \leadsto (\left(\sqrt{{b}^2 - 4 \cdot \left(c \cdot a\right)}\right) * \left(\frac{\frac{-1}{2}}{a}\right) + \left(\frac{-1}{2} \cdot \frac{b}{a}\right))_*\]
      5.4
    8. Taylor expanded around inf to get
      \[\color{red}{(\left(\sqrt{{b}^2 - 4 \cdot \left(c \cdot a\right)}\right) * \left(\frac{\frac{-1}{2}}{a}\right) + \left(\frac{-1}{2} \cdot \frac{b}{a}\right))_*} \leadsto \color{blue}{(\left(\sqrt{{b}^2 - 4 \cdot \left(c \cdot a\right)}\right) * \left(\frac{\frac{-1}{2}}{a}\right) + \left(\frac{-1}{2} \cdot \frac{b}{a}\right))_*}\]
      5.4
    9. Applied simplify to get
      \[(\left(\sqrt{{b}^2 - 4 \cdot \left(c \cdot a\right)}\right) * \left(\frac{\frac{-1}{2}}{a}\right) + \left(\frac{-1}{2} \cdot \frac{b}{a}\right))_* \leadsto (\left(\sqrt{{b}^2 - \left(4 \cdot c\right) \cdot a}\right) * \left(\frac{\frac{-1}{2}}{a}\right) + \left(\frac{\frac{-1}{2}}{\frac{a}{b}}\right))_*\]
      5.5

    10. Applied final simplification

    if 3.318237f+16 < b

    1. Started with
      \[\frac{\left(-b\right) - \sqrt{{b}^2 - 4 \cdot \left(a \cdot c\right)}}{2 \cdot a}\]
      25.3
    2. Applied taylor to get
      \[\frac{\left(-b\right) - \sqrt{{b}^2 - 4 \cdot \left(a \cdot c\right)}}{2 \cdot a} \leadsto \frac{2 \cdot \frac{c \cdot a}{b} - 2 \cdot b}{2 \cdot a}\]
      5.8
    3. Taylor expanded around inf to get
      \[\frac{\color{red}{2 \cdot \frac{c \cdot a}{b} - 2 \cdot b}}{2 \cdot a} \leadsto \frac{\color{blue}{2 \cdot \frac{c \cdot a}{b} - 2 \cdot b}}{2 \cdot a}\]
      5.8
    4. Applied simplify to get
      \[\color{red}{\frac{2 \cdot \frac{c \cdot a}{b} - 2 \cdot b}{2 \cdot a}} \leadsto \color{blue}{\frac{\frac{c}{b}}{1} - \frac{b}{a}}\]
      0.0
    5. Applied simplify to get
      \[\color{red}{\frac{\frac{c}{b}}{1}} - \frac{b}{a} \leadsto \color{blue}{\frac{c}{b}} - \frac{b}{a}\]
      0.0

  1. Removed slow pow expressions

Original test:


(lambda ((a default) (b default) (c default))
  #:name "The quadratic formula (r2)"
  (/ (- (- b) (sqrt (- (sqr b) (* 4 (* a c))))) (* 2 a))
  #:target
  (if (< b 0) (/ c (* a (/ (+ (- b) (sqrt (- (sqr b) (* 4 (* a c))))) (* 2 a)))) (/ (- (- b) (sqrt (- (sqr b) (* 4 (* a c))))) (* 2 a))))