\[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
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: 10.8 s
Input Error: 12.5
Output Error: 3.2
Log:
Profile: 🕒
\(\begin{cases} \frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \frac{d}{1} \cdot \frac{a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} & \text{when } c \le 1.5651492f+15 \\ \frac{b}{1} \cdot \frac{c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \frac{d \cdot a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} & \text{otherwise} \end{cases}\)

    if c < 1.5651492f+15

    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
      \[\frac{b \cdot c - a \cdot d}{\color{red}{{c}^2 + {d}^2}} \leadsto \frac{b \cdot c - a \cdot d}{\color{blue}{{\left(\sqrt{{c}^2 + {d}^2}\right)}^2}}\]
      10.9
    4. Applied simplify to get
      \[\frac{b \cdot c - a \cdot d}{{\color{red}{\left(\sqrt{{c}^2 + {d}^2}\right)}}^2} \leadsto \frac{b \cdot c - a \cdot d}{{\color{blue}{\left(\sqrt{c^2 + d^2}^*\right)}}^2}\]
      7.1
    5. Applied taylor to get
      \[\frac{b \cdot c - a \cdot d}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} \leadsto \frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \frac{d \cdot a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}\]
      7.1
    6. Taylor expanded around 0 to get
      \[\color{red}{\frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \frac{d \cdot a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}} \leadsto \color{blue}{\frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \frac{d \cdot a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}}\]
      7.1
    7. Using strategy rm
      7.1
    8. Applied *-un-lft-identity to get
      \[\frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \frac{d \cdot a}{{\color{red}{\left(\sqrt{c^2 + d^2}^*\right)}}^2} \leadsto \frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \frac{d \cdot a}{{\color{blue}{\left(1 \cdot \sqrt{c^2 + d^2}^*\right)}}^2}\]
      7.1
    9. Applied square-prod to get
      \[\frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \frac{d \cdot a}{\color{red}{{\left(1 \cdot \sqrt{c^2 + d^2}^*\right)}^2}} \leadsto \frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \frac{d \cdot a}{\color{blue}{{1}^2 \cdot {\left(\sqrt{c^2 + d^2}^*\right)}^2}}\]
      7.1
    10. Applied times-frac to get
      \[\frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \color{red}{\frac{d \cdot a}{{1}^2 \cdot {\left(\sqrt{c^2 + d^2}^*\right)}^2}} \leadsto \frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \color{blue}{\frac{d}{{1}^2} \cdot \frac{a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}}\]
      3.0
    11. Applied simplify to get
      \[\frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \color{red}{\frac{d}{{1}^2}} \cdot \frac{a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} \leadsto \frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \color{blue}{\frac{d}{1}} \cdot \frac{a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}\]
      3.0

    if 1.5651492f+15 < c

    1. Started with
      \[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
      20.3
    2. Using strategy rm
      20.3
    3. Applied add-sqr-sqrt to get
      \[\frac{b \cdot c - a \cdot d}{\color{red}{{c}^2 + {d}^2}} \leadsto \frac{b \cdot c - a \cdot d}{\color{blue}{{\left(\sqrt{{c}^2 + {d}^2}\right)}^2}}\]
      20.2
    4. Applied simplify to get
      \[\frac{b \cdot c - a \cdot d}{{\color{red}{\left(\sqrt{{c}^2 + {d}^2}\right)}}^2} \leadsto \frac{b \cdot c - a \cdot d}{{\color{blue}{\left(\sqrt{c^2 + d^2}^*\right)}}^2}\]
      13.4
    5. Applied taylor to get
      \[\frac{b \cdot c - a \cdot d}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} \leadsto \frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \frac{d \cdot a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}\]
      13.4
    6. Taylor expanded around 0 to get
      \[\color{red}{\frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \frac{d \cdot a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}} \leadsto \color{blue}{\frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \frac{d \cdot a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}}\]
      13.4
    7. Using strategy rm
      13.4
    8. Applied *-un-lft-identity to get
      \[\frac{b \cdot c}{{\color{red}{\left(\sqrt{c^2 + d^2}^*\right)}}^2} - \frac{d \cdot a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} \leadsto \frac{b \cdot c}{{\color{blue}{\left(1 \cdot \sqrt{c^2 + d^2}^*\right)}}^2} - \frac{d \cdot a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}\]
      13.4
    9. Applied square-prod to get
      \[\frac{b \cdot c}{\color{red}{{\left(1 \cdot \sqrt{c^2 + d^2}^*\right)}^2}} - \frac{d \cdot a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} \leadsto \frac{b \cdot c}{\color{blue}{{1}^2 \cdot {\left(\sqrt{c^2 + d^2}^*\right)}^2}} - \frac{d \cdot a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}\]
      13.4
    10. Applied times-frac to get
      \[\color{red}{\frac{b \cdot c}{{1}^2 \cdot {\left(\sqrt{c^2 + d^2}^*\right)}^2}} - \frac{d \cdot a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} \leadsto \color{blue}{\frac{b}{{1}^2} \cdot \frac{c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}} - \frac{d \cdot a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}\]
      3.7
    11. Applied simplify to get
      \[\color{red}{\frac{b}{{1}^2}} \cdot \frac{c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \frac{d \cdot a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} \leadsto \color{blue}{\frac{b}{1}} \cdot \frac{c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} - \frac{d \cdot a}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}\]
      3.7

  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))))))