\[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
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: 13.5 s
Input Error: 25.3
Output Error: 20.3
Log:
Profile: 🕒
\(\begin{cases} \frac{1}{\frac{{c}^2 + {d}^2}{b \cdot c - a \cdot d}} & \text{when } \frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2} \le -1.4069939366766694 \cdot 10^{-241} \\ \frac{\frac{c \cdot b}{\sqrt{c^2 + d^2}^*}}{\sqrt{c^2 + d^2}^*} & \text{when } \frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2} \le 0.0 \\ {\left(\frac{\sqrt{c \cdot b - d \cdot a}}{\sqrt{c^2 + d^2}^*}\right)}^2 & \text{otherwise} \end{cases}\)

    if (/ (- (* b c) (* a d)) (+ (sqr c) (sqr d))) < -1.4069939366766694e-241

    1. Started with
      \[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
      9.9
    2. Using strategy rm
      9.9
    3. Applied clear-num to get
      \[\color{red}{\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}} \leadsto \color{blue}{\frac{1}{\frac{{c}^2 + {d}^2}{b \cdot c - a \cdot d}}}\]
      10.0

    if -1.4069939366766694e-241 < (/ (- (* b c) (* a d)) (+ (sqr c) (sqr d))) < 0.0

    1. Started with
      \[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
      26.1
    2. Using strategy rm
      26.1
    3. Applied clear-num to get
      \[\color{red}{\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}} \leadsto \color{blue}{\frac{1}{\frac{{c}^2 + {d}^2}{b \cdot c - a \cdot d}}}\]
      26.1
    4. Using strategy rm
      26.1
    5. Applied add-sqr-sqrt to get
      \[\frac{1}{\frac{{c}^2 + {d}^2}{\color{red}{b \cdot c - a \cdot d}}} \leadsto \frac{1}{\frac{{c}^2 + {d}^2}{\color{blue}{{\left(\sqrt{b \cdot c - a \cdot d}\right)}^2}}}\]
      47.5
    6. Applied add-sqr-sqrt to get
      \[\frac{1}{\frac{\color{red}{{c}^2 + {d}^2}}{{\left(\sqrt{b \cdot c - a \cdot d}\right)}^2}} \leadsto \frac{1}{\frac{\color{blue}{{\left(\sqrt{{c}^2 + {d}^2}\right)}^2}}{{\left(\sqrt{b \cdot c - a \cdot d}\right)}^2}}\]
      47.5
    7. Applied square-undiv to get
      \[\frac{1}{\color{red}{\frac{{\left(\sqrt{{c}^2 + {d}^2}\right)}^2}{{\left(\sqrt{b \cdot c - a \cdot d}\right)}^2}}} \leadsto \frac{1}{\color{blue}{{\left(\frac{\sqrt{{c}^2 + {d}^2}}{\sqrt{b \cdot c - a \cdot d}}\right)}^2}}\]
      47.5
    8. Applied simplify to get
      \[\frac{1}{{\color{red}{\left(\frac{\sqrt{{c}^2 + {d}^2}}{\sqrt{b \cdot c - a \cdot d}}\right)}}^2} \leadsto \frac{1}{{\color{blue}{\left(\frac{\sqrt{c^2 + d^2}^*}{\sqrt{c \cdot b - a \cdot d}}\right)}}^2}\]
      35.4
    9. Applied taylor to get
      \[\frac{1}{{\left(\frac{\sqrt{c^2 + d^2}^*}{\sqrt{c \cdot b - a \cdot d}}\right)}^2} \leadsto \frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}\]
      24.4
    10. Taylor expanded around 0 to get
      \[\color{red}{\frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}} \leadsto \color{blue}{\frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2}}\]
      24.4
    11. Applied simplify to get
      \[\frac{b \cdot c}{{\left(\sqrt{c^2 + d^2}^*\right)}^2} \leadsto \frac{\frac{c \cdot b}{\sqrt{c^2 + d^2}^*}}{\sqrt{c^2 + d^2}^*}\]
      11.6

    12. Applied final simplification

    if 0.0 < (/ (- (* b c) (* a d)) (+ (sqr c) (sqr d)))

    1. Started with
      \[\frac{b \cdot c - a \cdot d}{{c}^2 + {d}^2}\]
      33.1
    2. Using strategy rm
      33.1
    3. Applied add-sqr-sqrt to get
      \[\frac{b \cdot c - a \cdot d}{\color{red}{{c}^2 + {d}^2}} \leadsto \frac{b \cdot c - a \cdot d}{\color{blue}{{\left(\sqrt{{c}^2 + {d}^2}\right)}^2}}\]
      33.1
    4. Applied add-sqr-sqrt to get
      \[\frac{\color{red}{b \cdot c - a \cdot d}}{{\left(\sqrt{{c}^2 + {d}^2}\right)}^2} \leadsto \frac{\color{blue}{{\left(\sqrt{b \cdot c - a \cdot d}\right)}^2}}{{\left(\sqrt{{c}^2 + {d}^2}\right)}^2}\]
      33.2
    5. Applied square-undiv to get
      \[\color{red}{\frac{{\left(\sqrt{b \cdot c - a \cdot d}\right)}^2}{{\left(\sqrt{{c}^2 + {d}^2}\right)}^2}} \leadsto \color{blue}{{\left(\frac{\sqrt{b \cdot c - a \cdot d}}{\sqrt{{c}^2 + {d}^2}}\right)}^2}\]
      33.2
    6. Applied simplify to get
      \[{\color{red}{\left(\frac{\sqrt{b \cdot c - a \cdot d}}{\sqrt{{c}^2 + {d}^2}}\right)}}^2 \leadsto {\color{blue}{\left(\frac{\sqrt{c \cdot b - d \cdot a}}{\sqrt{c^2 + d^2}^*}\right)}}^2\]
      31.7

  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))))))