\[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
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: 12.5 s
Input Error: 12.9
Output Error: 4.3
Log:
Profile: 🕒
\(\begin{cases} \frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + {\left(\left|d\right|\right)}^2} & \text{when } d \le -3.6129147f-16 \\ \frac{b}{\left|c\right|} \cdot \frac{c}{\left|c\right|} - \frac{\frac{d \cdot a}{\left|c\right|}}{\left|c\right|} & \text{when } d \le 2.3232377f-12 \\ \frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + {\left(\left|d\right|\right)}^2} & \text{when } d \le 1.5011559f+10 \\ \frac{c}{d} \cdot \frac{b}{d} - \frac{a}{d} & \text{otherwise} \end{cases}\)

    if d < -3.6129147f-16 or 2.3232377f-12 < d < 1.5011559f+10

    1. Started with
      \[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
      11.9
    2. Using strategy rm
      11.9
    3. Applied add-sqr-sqrt to get
      \[\frac{b \cdot c - a \cdot d}{\color{red}{{c}^2} + {d}^2} \leadsto \frac{b \cdot c - a \cdot d}{\color{blue}{{\left(\sqrt{{c}^2}\right)}^2} + {d}^2}\]
      11.9
    4. Applied simplify to get
      \[\frac{b \cdot c - a \cdot d}{{\color{red}{\left(\sqrt{{c}^2}\right)}}^2 + {d}^2} \leadsto \frac{b \cdot c - a \cdot d}{{\color{blue}{\left(\left|c\right|\right)}}^2 + {d}^2}\]
      10.2
    5. Using strategy rm
      10.2
    6. Applied add-sqr-sqrt to get
      \[\frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + \color{red}{{d}^2}} \leadsto \frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + \color{blue}{{\left(\sqrt{{d}^2}\right)}^2}}\]
      10.1
    7. Applied simplify to get
      \[\frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + {\color{red}{\left(\sqrt{{d}^2}\right)}}^2} \leadsto \frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + {\color{blue}{\left(\left|d\right|\right)}}^2}\]
      7.9

    if -3.6129147f-16 < d < 2.3232377f-12

    1. Started with
      \[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
      10.5
    2. Using strategy rm
      10.5
    3. Applied add-sqr-sqrt to get
      \[\frac{b \cdot c - a \cdot d}{\color{red}{{c}^2} + {d}^2} \leadsto \frac{b \cdot c - a \cdot d}{\color{blue}{{\left(\sqrt{{c}^2}\right)}^2} + {d}^2}\]
      10.5
    4. Applied simplify to get
      \[\frac{b \cdot c - a \cdot d}{{\color{red}{\left(\sqrt{{c}^2}\right)}}^2 + {d}^2} \leadsto \frac{b \cdot c - a \cdot d}{{\color{blue}{\left(\left|c\right|\right)}}^2 + {d}^2}\]
      6.7
    5. Using strategy rm
      6.7
    6. Applied add-sqr-sqrt to get
      \[\color{red}{\frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + {d}^2}} \leadsto \color{blue}{{\left(\sqrt{\frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + {d}^2}}\right)}^2}\]
      17.8
    7. Applied taylor to get
      \[{\left(\sqrt{\frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + {d}^2}}\right)}^2 \leadsto {\left(\sqrt{\frac{b \cdot c}{{\left(\left|c\right|\right)}^2} - \frac{d \cdot a}{{\left(\left|c\right|\right)}^2}}\right)}^2\]
      17.4
    8. Taylor expanded around 0 to get
      \[{\left(\sqrt{\color{red}{\frac{b \cdot c}{{\left(\left|c\right|\right)}^2} - \frac{d \cdot a}{{\left(\left|c\right|\right)}^2}}}\right)}^2 \leadsto {\left(\sqrt{\color{blue}{\frac{b \cdot c}{{\left(\left|c\right|\right)}^2} - \frac{d \cdot a}{{\left(\left|c\right|\right)}^2}}}\right)}^2\]
      17.4
    9. Applied simplify to get
      \[{\left(\sqrt{\frac{b \cdot c}{{\left(\left|c\right|\right)}^2} - \frac{d \cdot a}{{\left(\left|c\right|\right)}^2}}\right)}^2 \leadsto \frac{b}{\left|c\right|} \cdot \frac{c}{\left|c\right|} - \frac{\frac{d \cdot a}{\left|c\right|}}{\left|c\right|}\]
      0.6

    10. Applied final simplification

    if 1.5011559f+10 < d

    1. Started with
      \[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
      18.8
    2. Using strategy rm
      18.8
    3. Applied add-sqr-sqrt to get
      \[\frac{b \cdot c - a \cdot d}{\color{red}{{c}^2} + {d}^2} \leadsto \frac{b \cdot c - a \cdot d}{\color{blue}{{\left(\sqrt{{c}^2}\right)}^2} + {d}^2}\]
      18.8
    4. Applied simplify to get
      \[\frac{b \cdot c - a \cdot d}{{\color{red}{\left(\sqrt{{c}^2}\right)}}^2 + {d}^2} \leadsto \frac{b \cdot c - a \cdot d}{{\color{blue}{\left(\left|c\right|\right)}}^2 + {d}^2}\]
      18.7
    5. Using strategy rm
      18.7
    6. Applied add-sqr-sqrt to get
      \[\color{red}{\frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + {d}^2}} \leadsto \color{blue}{{\left(\sqrt{\frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + {d}^2}}\right)}^2}\]
      21.3
    7. Applied taylor to get
      \[{\left(\sqrt{\frac{b \cdot c - a \cdot d}{{\left(\left|c\right|\right)}^2 + {d}^2}}\right)}^2 \leadsto {\left(\sqrt{\frac{b \cdot c}{{d}^2} - \frac{a}{d}}\right)}^2\]
      15.9
    8. Taylor expanded around inf to get
      \[{\left(\sqrt{\color{red}{\frac{b \cdot c}{{d}^2} - \frac{a}{d}}}\right)}^2 \leadsto {\left(\sqrt{\color{blue}{\frac{b \cdot c}{{d}^2} - \frac{a}{d}}}\right)}^2\]
      15.9
    9. Applied simplify to get
      \[{\left(\sqrt{\frac{b \cdot c}{{d}^2} - \frac{a}{d}}\right)}^2 \leadsto \frac{c}{d} \cdot \frac{b}{d} - \frac{a}{d}\]
      0.4

    10. 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))))))