\[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
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: 14.1 s
Input Error: 12.5
Output Error: 4.7
Log:
Profile: 🕒
\(\begin{cases} \frac{c}{d} \cdot \frac{b}{d} - \frac{a}{d} & \text{when } d \le -1.4521623f+15 \\ \frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + {\left(\left|d\right|\right)}^2} & \text{when } d \le -8.914957f-21 \\ \frac{b}{\left|c\right|} \cdot \frac{c}{\left|c\right|} - \frac{a}{\left|c\right|} \cdot \frac{d}{\left|c\right|} & \text{when } d \le 1.3204445f-22 \\ \frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + {\left(\left|d\right|\right)}^2} & \text{otherwise} \end{cases}\)

    if d < -1.4521623f+15

    1. Started with
      \[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
      20.5
    2. Using strategy rm
      20.5
    3. Applied add-sqr-sqrt to get
      \[\frac{b \cdot c - a \cdot d}{\color{red}{{c}^2} + {d}^2} \leadsto \frac{b \cdot c - a \cdot d}{\color{blue}{{\left(\sqrt{{c}^2}\right)}^2} + {d}^2}\]
      20.5
    4. Applied simplify to get
      \[\frac{b \cdot c - a \cdot d}{{\color{red}{\left(\sqrt{{c}^2}\right)}}^2 + {d}^2} \leadsto \frac{b \cdot c - a \cdot d}{{\color{blue}{\left(\left|c\right|\right)}}^2 + {d}^2}\]
      20.4
    5. Using strategy rm
      20.4
    6. Applied flip-- to get
      \[\frac{\color{red}{b \cdot c - a \cdot d}}{{\left(\left|c\right|\right)}^2 + {d}^2} \leadsto \frac{\color{blue}{\frac{{\left(b \cdot c\right)}^2 - {\left(a \cdot d\right)}^2}{b \cdot c + a \cdot d}}}{{\left(\left|c\right|\right)}^2 + {d}^2}\]
      23.6
    7. Applied associate-/l/ to get
      \[\color{red}{\frac{\frac{{\left(b \cdot c\right)}^2 - {\left(a \cdot d\right)}^2}{b \cdot c + a \cdot d}}{{\left(\left|c\right|\right)}^2 + {d}^2}} \leadsto \color{blue}{\frac{{\left(b \cdot c\right)}^2 - {\left(a \cdot d\right)}^2}{\left({\left(\left|c\right|\right)}^2 + {d}^2\right) \cdot \left(b \cdot c + a \cdot d\right)}}\]
      23.6
    8. Applied taylor to get
      \[\frac{{\left(b \cdot c\right)}^2 - {\left(a \cdot d\right)}^2}{\left({\left(\left|c\right|\right)}^2 + {d}^2\right) \cdot \left(b \cdot c + a \cdot d\right)} \leadsto \frac{b \cdot c}{{d}^2} - \frac{a}{d}\]
      6.0
    9. Taylor expanded around inf to get
      \[\color{red}{\frac{b \cdot c}{{d}^2} - \frac{a}{d}} \leadsto \color{blue}{\frac{b \cdot c}{{d}^2} - \frac{a}{d}}\]
      6.0
    10. Applied simplify to get
      \[\frac{b \cdot c}{{d}^2} - \frac{a}{d} \leadsto \frac{c}{d} \cdot \frac{b}{d} - \frac{a}{d}\]
      0.3

    11. Applied final simplification

    if -1.4521623f+15 < d < -8.914957f-21 or 1.3204445f-22 < d

    1. Started with
      \[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
      11.0
    2. Using strategy rm
      11.0
    3. Applied add-sqr-sqrt to get
      \[\frac{b \cdot c - a \cdot d}{\color{red}{{c}^2} + {d}^2} \leadsto \frac{b \cdot c - a \cdot d}{\color{blue}{{\left(\sqrt{{c}^2}\right)}^2} + {d}^2}\]
      11.0
    4. Applied simplify to get
      \[\frac{b \cdot c - a \cdot d}{{\color{red}{\left(\sqrt{{c}^2}\right)}}^2 + {d}^2} \leadsto \frac{b \cdot c - a \cdot d}{{\color{blue}{\left(\left|c\right|\right)}}^2 + {d}^2}\]
      9.2
    5. Using strategy rm
      9.2
    6. Applied add-sqr-sqrt to get
      \[\frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + \color{red}{{d}^2}} \leadsto \frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + \color{blue}{{\left(\sqrt{{d}^2}\right)}^2}}\]
      9.2
    7. Applied simplify to get
      \[\frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + {\color{red}{\left(\sqrt{{d}^2}\right)}}^2} \leadsto \frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + {\color{blue}{\left(\left|d\right|\right)}}^2}\]
      7.4

    if -8.914957f-21 < d < 1.3204445f-22

    1. Started with
      \[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
      10.4
    2. Using strategy rm
      10.4
    3. Applied add-sqr-sqrt to get
      \[\frac{b \cdot c - a \cdot d}{\color{red}{{c}^2} + {d}^2} \leadsto \frac{b \cdot c - a \cdot d}{\color{blue}{{\left(\sqrt{{c}^2}\right)}^2} + {d}^2}\]
      10.4
    4. Applied simplify to get
      \[\frac{b \cdot c - a \cdot d}{{\color{red}{\left(\sqrt{{c}^2}\right)}}^2 + {d}^2} \leadsto \frac{b \cdot c - a \cdot d}{{\color{blue}{\left(\left|c\right|\right)}}^2 + {d}^2}\]
      5.9
    5. Using strategy rm
      5.9
    6. Applied flip-- to get
      \[\frac{\color{red}{b \cdot c - a \cdot d}}{{\left(\left|c\right|\right)}^2 + {d}^2} \leadsto \frac{\color{blue}{\frac{{\left(b \cdot c\right)}^2 - {\left(a \cdot d\right)}^2}{b \cdot c + a \cdot d}}}{{\left(\left|c\right|\right)}^2 + {d}^2}\]
      14.8
    7. Applied associate-/l/ to get
      \[\color{red}{\frac{\frac{{\left(b \cdot c\right)}^2 - {\left(a \cdot d\right)}^2}{b \cdot c + a \cdot d}}{{\left(\left|c\right|\right)}^2 + {d}^2}} \leadsto \color{blue}{\frac{{\left(b \cdot c\right)}^2 - {\left(a \cdot d\right)}^2}{\left({\left(\left|c\right|\right)}^2 + {d}^2\right) \cdot \left(b \cdot c + a \cdot d\right)}}\]
      14.8
    8. Applied taylor to get
      \[\frac{{\left(b \cdot c\right)}^2 - {\left(a \cdot d\right)}^2}{\left({\left(\left|c\right|\right)}^2 + {d}^2\right) \cdot \left(b \cdot c + a \cdot d\right)} \leadsto \frac{b \cdot c}{{\left(\left|c\right|\right)}^2} - \frac{d \cdot a}{{\left(\left|c\right|\right)}^2}\]
      5.8
    9. Taylor expanded around 0 to get
      \[\color{red}{\frac{b \cdot c}{{\left(\left|c\right|\right)}^2} - \frac{d \cdot a}{{\left(\left|c\right|\right)}^2}} \leadsto \color{blue}{\frac{b \cdot c}{{\left(\left|c\right|\right)}^2} - \frac{d \cdot a}{{\left(\left|c\right|\right)}^2}}\]
      5.8
    10. Applied simplify to get
      \[\frac{b \cdot c}{{\left(\left|c\right|\right)}^2} - \frac{d \cdot a}{{\left(\left|c\right|\right)}^2} \leadsto \frac{b}{\left|c\right|} \cdot \frac{c}{\left|c\right|} - \frac{a}{\left|c\right|} \cdot \frac{d}{\left|c\right|}\]
      0

    11. Applied final simplification

  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))))))