\[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
Test:
Complex division, imag part
Bits:
128 bits
Bits error versus a
Bits error versus b
Bits error versus c
Bits error versus d
Time: 12.7 s
Input Error: 24.7
Output Error: 7.4
Log:
Profile: 🕒
\(\begin{cases} -\frac{d}{\sqrt{c^2 + d^2}^*} \cdot \frac{a}{\sqrt{c^2 + d^2}^*} & \text{when } d \le -4.083719811311209 \cdot 10^{+189} \\ \frac{b}{(\left(\frac{d}{c}\right) * d + c)_*} - \frac{d \cdot a}{(c * c + \left(d \cdot d\right))_*} & \text{when } d \le 4.999857972009831 \cdot 10^{+168} \\ -\frac{d}{\sqrt{c^2 + d^2}^*} \cdot \frac{a}{\sqrt{c^2 + d^2}^*} & \text{otherwise} \end{cases}\)

    if d < -4.083719811311209e+189 or 4.999857972009831e+168 < d

    1. Started with
      \[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
      40.1
    2. Using strategy rm
      40.1
    3. Applied div-sub to get
      \[\color{red}{\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}} \leadsto \color{blue}{\frac{b \cdot c}{{c}^2 + {d}^2} - \frac{a \cdot d}{{c}^2 + {d}^2}}\]
      40.1
    4. Using strategy rm
      40.1
    5. Applied *-un-lft-identity to get
      \[\frac{b \cdot c}{\color{red}{{c}^2 + {d}^2}} - \frac{a \cdot d}{{c}^2 + {d}^2} \leadsto \frac{b \cdot c}{\color{blue}{1 \cdot \left({c}^2 + {d}^2\right)}} - \frac{a \cdot d}{{c}^2 + {d}^2}\]
      40.1
    6. Applied times-frac to get
      \[\color{red}{\frac{b \cdot c}{1 \cdot \left({c}^2 + {d}^2\right)}} - \frac{a \cdot d}{{c}^2 + {d}^2} \leadsto \color{blue}{\frac{b}{1} \cdot \frac{c}{{c}^2 + {d}^2}} - \frac{a \cdot d}{{c}^2 + {d}^2}\]
      36.9
    7. Using strategy rm
      36.9
    8. Applied add-sqr-sqrt to get
      \[\frac{b}{1} \cdot \frac{c}{{c}^2 + {d}^2} - \frac{a \cdot d}{\color{red}{{c}^2 + {d}^2}} \leadsto \frac{b}{1} \cdot \frac{c}{{c}^2 + {d}^2} - \frac{a \cdot d}{\color{blue}{{\left(\sqrt{{c}^2 + {d}^2}\right)}^2}}\]
      36.9
    9. Applied add-sqr-sqrt to get
      \[\frac{b}{1} \cdot \frac{c}{{c}^2 + {d}^2} - \frac{\color{red}{a \cdot d}}{{\left(\sqrt{{c}^2 + {d}^2}\right)}^2} \leadsto \frac{b}{1} \cdot \frac{c}{{c}^2 + {d}^2} - \frac{\color{blue}{{\left(\sqrt{a \cdot d}\right)}^2}}{{\left(\sqrt{{c}^2 + {d}^2}\right)}^2}\]
      50.8
    10. Applied square-undiv to get
      \[\frac{b}{1} \cdot \frac{c}{{c}^2 + {d}^2} - \color{red}{\frac{{\left(\sqrt{a \cdot d}\right)}^2}{{\left(\sqrt{{c}^2 + {d}^2}\right)}^2}} \leadsto \frac{b}{1} \cdot \frac{c}{{c}^2 + {d}^2} - \color{blue}{{\left(\frac{\sqrt{a \cdot d}}{\sqrt{{c}^2 + {d}^2}}\right)}^2}\]
      50.8
    11. Applied simplify to get
      \[\frac{b}{1} \cdot \frac{c}{{c}^2 + {d}^2} - {\color{red}{\left(\frac{\sqrt{a \cdot d}}{\sqrt{{c}^2 + {d}^2}}\right)}}^2 \leadsto \frac{b}{1} \cdot \frac{c}{{c}^2 + {d}^2} - {\color{blue}{\left(\frac{\sqrt{d \cdot a}}{\sqrt{c^2 + d^2}^*}\right)}}^2\]
      44.6
    12. Applied taylor to get
      \[\frac{b}{1} \cdot \frac{c}{{c}^2 + {d}^2} - {\left(\frac{\sqrt{d \cdot a}}{\sqrt{c^2 + d^2}^*}\right)}^2 \leadsto \frac{b}{1} \cdot 0 - {\left(\frac{\sqrt{d \cdot a}}{\sqrt{c^2 + d^2}^*}\right)}^2\]
      44.6
    13. Taylor expanded around 0 to get
      \[\frac{b}{1} \cdot \color{red}{0} - {\left(\frac{\sqrt{d \cdot a}}{\sqrt{c^2 + d^2}^*}\right)}^2 \leadsto \frac{b}{1} \cdot \color{blue}{0} - {\left(\frac{\sqrt{d \cdot a}}{\sqrt{c^2 + d^2}^*}\right)}^2\]
      44.6
    14. Applied simplify to get
      \[\frac{b}{1} \cdot 0 - {\left(\frac{\sqrt{d \cdot a}}{\sqrt{c^2 + d^2}^*}\right)}^2 \leadsto -\frac{d}{\sqrt{c^2 + d^2}^*} \cdot \frac{a}{\sqrt{c^2 + d^2}^*}\]
      0.0

    15. Applied final simplification

    if -4.083719811311209e+189 < d < 4.999857972009831e+168

    1. Started with
      \[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
      20.3
    2. Using strategy rm
      20.3
    3. Applied div-sub to get
      \[\color{red}{\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}} \leadsto \color{blue}{\frac{b \cdot c}{{c}^2 + {d}^2} - \frac{a \cdot d}{{c}^2 + {d}^2}}\]
      20.3
    4. Using strategy rm
      20.3
    5. Applied associate-/l* to get
      \[\color{red}{\frac{b \cdot c}{{c}^2 + {d}^2}} - \frac{a \cdot d}{{c}^2 + {d}^2} \leadsto \color{blue}{\frac{b}{\frac{{c}^2 + {d}^2}{c}}} - \frac{a \cdot d}{{c}^2 + {d}^2}\]
      18.9
    6. Applied taylor to get
      \[\frac{b}{\frac{{c}^2 + {d}^2}{c}} - \frac{a \cdot d}{{c}^2 + {d}^2} \leadsto \frac{b}{c + \frac{{d}^2}{c}} - \frac{a \cdot d}{{c}^2 + {d}^2}\]
      10.1
    7. Taylor expanded around 0 to get
      \[\frac{b}{\color{red}{c + \frac{{d}^2}{c}}} - \frac{a \cdot d}{{c}^2 + {d}^2} \leadsto \frac{b}{\color{blue}{c + \frac{{d}^2}{c}}} - \frac{a \cdot d}{{c}^2 + {d}^2}\]
      10.1
    8. Applied simplify to get
      \[\frac{b}{c + \frac{{d}^2}{c}} - \frac{a \cdot d}{{c}^2 + {d}^2} \leadsto \frac{b}{\frac{d}{\frac{c}{d}} + c} - \frac{a \cdot d}{(c * c + \left(d \cdot d\right))_*}\]
      9.6

    9. Applied final simplification
    10. Applied simplify to get
      \[\color{red}{\frac{b}{\frac{d}{\frac{c}{d}} + c} - \frac{a \cdot d}{(c * c + \left(d \cdot d\right))_*}} \leadsto \color{blue}{\frac{b}{(\left(\frac{d}{c}\right) * d + c)_*} - \frac{d \cdot a}{(c * c + \left(d \cdot d\right))_*}}\]
      9.6

  1. Removed slow pow expressions

Original test:


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