\[\frac{a \cdot c + b \cdot d}{{c}^2 + {d}^2}\]
Test:
Complex division, real part
Bits:
128 bits
Bits error versus a
Bits error versus b
Bits error versus c
Bits error versus d
Time: 12.3 s
Input Error: 13.2
Output Error: 2.3
Log:
Profile: 🕒
\(\begin{cases} (\left(\frac{b}{\left|d\right|}\right) * \left(\frac{d}{\left|d\right|}\right) + \left(\frac{a}{\left|d\right|} \cdot \frac{c}{\left|d\right|}\right))_* & \text{when } d \le -1.01464965f+11 \\ \frac{a \cdot c + b \cdot d}{{\left(\left|c\right|\right)}^2 + {d}^2} & \text{when } d \le -2.1758005f-17 \\ (\left(\frac{b}{c}\right) * \left(\frac{d}{c}\right) + \left(\frac{a}{c}\right))_* & \text{when } d \le 1.421191f-23 \\ \frac{a \cdot c + b \cdot d}{{\left(\left|c\right|\right)}^2 + {d}^2} & \text{when } d \le 4.628637f+09 \\ (\left(\frac{b}{\left|d\right|}\right) * \left(\frac{d}{\left|d\right|}\right) + \left(\frac{a}{\left|d\right|} \cdot \frac{c}{\left|d\right|}\right))_* & \text{otherwise} \end{cases}\)

    if d < -1.01464965f+11 or 4.628637f+09 < d

    1. Started with
      \[\frac{a \cdot c + b \cdot d}{{c}^2 + {d}^2}\]
      20.2
    2. Using strategy rm
      20.2
    3. Applied add-sqr-sqrt to get
      \[\frac{a \cdot c + b \cdot d}{{c}^2 + \color{red}{{d}^2}} \leadsto \frac{a \cdot c + b \cdot d}{{c}^2 + \color{blue}{{\left(\sqrt{{d}^2}\right)}^2}}\]
      20.2
    4. Applied simplify to get
      \[\frac{a \cdot c + b \cdot d}{{c}^2 + {\color{red}{\left(\sqrt{{d}^2}\right)}}^2} \leadsto \frac{a \cdot c + b \cdot d}{{c}^2 + {\color{blue}{\left(\left|d\right|\right)}}^2}\]
      15.6
    5. Using strategy rm
      15.6
    6. Applied add-cube-cbrt to get
      \[\color{red}{\frac{a \cdot c + b \cdot d}{{c}^2 + {\left(\left|d\right|\right)}^2}} \leadsto \color{blue}{{\left(\sqrt[3]{\frac{a \cdot c + b \cdot d}{{c}^2 + {\left(\left|d\right|\right)}^2}}\right)}^3}\]
      15.7
    7. Applied taylor to get
      \[{\left(\sqrt[3]{\frac{a \cdot c + b \cdot d}{{c}^2 + {\left(\left|d\right|\right)}^2}}\right)}^3 \leadsto {\left(\sqrt[3]{\frac{c \cdot a}{{\left(\left|d\right|\right)}^2} + \frac{b \cdot d}{{\left(\left|d\right|\right)}^2}}\right)}^3\]
      12.8
    8. Taylor expanded around 0 to get
      \[{\left(\sqrt[3]{\color{red}{\frac{c \cdot a}{{\left(\left|d\right|\right)}^2} + \frac{b \cdot d}{{\left(\left|d\right|\right)}^2}}}\right)}^3 \leadsto {\left(\sqrt[3]{\color{blue}{\frac{c \cdot a}{{\left(\left|d\right|\right)}^2} + \frac{b \cdot d}{{\left(\left|d\right|\right)}^2}}}\right)}^3\]
      12.8
    9. Applied simplify to get
      \[{\left(\sqrt[3]{\frac{c \cdot a}{{\left(\left|d\right|\right)}^2} + \frac{b \cdot d}{{\left(\left|d\right|\right)}^2}}\right)}^3 \leadsto (\left(\frac{b}{\left|d\right|}\right) * \left(\frac{d}{\left|d\right|}\right) + \left(\frac{a}{\left|d\right|} \cdot \frac{c}{\left|d\right|}\right))_*\]
      0.0

    10. Applied final simplification

    if -1.01464965f+11 < d < -2.1758005f-17 or 1.421191f-23 < d < 4.628637f+09

    1. Started with
      \[\frac{a \cdot c + b \cdot d}{{c}^2 + {d}^2}\]
      7.7
    2. Using strategy rm
      7.7
    3. Applied add-sqr-sqrt to get
      \[\frac{a \cdot c + b \cdot d}{\color{red}{{c}^2} + {d}^2} \leadsto \frac{a \cdot c + b \cdot d}{\color{blue}{{\left(\sqrt{{c}^2}\right)}^2} + {d}^2}\]
      7.7
    4. Applied simplify to get
      \[\frac{a \cdot c + b \cdot d}{{\color{red}{\left(\sqrt{{c}^2}\right)}}^2 + {d}^2} \leadsto \frac{a \cdot c + b \cdot d}{{\color{blue}{\left(\left|c\right|\right)}}^2 + {d}^2}\]
      4.9

    if -2.1758005f-17 < d < 1.421191f-23

    1. Started with
      \[\frac{a \cdot c + b \cdot d}{{c}^2 + {d}^2}\]
      10.5
    2. Using strategy rm
      10.5
    3. Applied add-cube-cbrt to get
      \[\frac{a \cdot c + b \cdot d}{{c}^2 + \color{red}{{d}^2}} \leadsto \frac{a \cdot c + b \cdot d}{{c}^2 + \color{blue}{{\left(\sqrt[3]{{d}^2}\right)}^3}}\]
      10.5
    4. Applied taylor to get
      \[\frac{a \cdot c + b \cdot d}{{c}^2 + {\left(\sqrt[3]{{d}^2}\right)}^3} \leadsto \frac{a}{c} + \frac{b \cdot d}{{c}^2}\]
      3.2
    5. Taylor expanded around inf to get
      \[\color{red}{\frac{a}{c} + \frac{b \cdot d}{{c}^2}} \leadsto \color{blue}{\frac{a}{c} + \frac{b \cdot d}{{c}^2}}\]
      3.2
    6. Applied simplify to get
      \[\frac{a}{c} + \frac{b \cdot d}{{c}^2} \leadsto (\left(\frac{b}{c}\right) * \left(\frac{d}{c}\right) + \left(\frac{a}{c}\right))_*\]
      1.3

    7. Applied final simplification

  1. Removed slow pow expressions

Original test:


(lambda ((a default) (b default) (c default) (d default))
  #:name "Complex division, real part"
  (/ (+ (* a c) (* b d)) (+ (sqr c) (sqr d)))
  #:target
  (if (< (fabs d) (fabs c)) (/ (+ a (* b (/ d c))) (+ c (* d (/ d c)))) (/ (+ b (* a (/ c d))) (+ d (* c (/ c d))))))