Average Error: 25.8 → 4.8
Time: 47.4s
Precision: 64
Internal Precision: 576
\[\frac{b \cdot c - a \cdot d}{c \cdot c + d \cdot d}\]
\[\begin{array}{l} \mathbf{if}\;a \le -3.033774745784645 \cdot 10^{+77} \lor \neg \left(a \le 2.753179196369121 \cdot 10^{+48}\right):\\ \;\;\;\;\frac{\frac{c \cdot b}{\sqrt{c^2 + d^2}^*} - \frac{d}{\sqrt{c^2 + d^2}^*} \cdot a}{\sqrt{c^2 + d^2}^*}\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{c}{\frac{\sqrt{c^2 + d^2}^*}{b}} - \frac{a \cdot d}{\sqrt{c^2 + d^2}^*}}{\sqrt{c^2 + d^2}^*}\\ \end{array}\]

Error

Bits error versus a

Bits error versus b

Bits error versus c

Bits error versus d

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Target

Original25.8
Target0.4
Herbie4.8
\[\begin{array}{l} \mathbf{if}\;\left|d\right| \lt \left|c\right|:\\ \;\;\;\;\frac{b - a \cdot \frac{d}{c}}{c + d \cdot \frac{d}{c}}\\ \mathbf{else}:\\ \;\;\;\;\frac{\left(-a\right) + b \cdot \frac{c}{d}}{d + c \cdot \frac{c}{d}}\\ \end{array}\]

Derivation

  1. Split input into 2 regimes
  2. if a < -3.033774745784645e+77 or 2.753179196369121e+48 < a

    1. Initial program 33.3

      \[\frac{b \cdot c - a \cdot d}{c \cdot c + d \cdot d}\]
    2. Using strategy rm
    3. Applied add-sqr-sqrt33.3

      \[\leadsto \frac{b \cdot c - a \cdot d}{\color{blue}{\sqrt{c \cdot c + d \cdot d} \cdot \sqrt{c \cdot c + d \cdot d}}}\]
    4. Applied *-un-lft-identity33.3

      \[\leadsto \frac{\color{blue}{1 \cdot \left(b \cdot c - a \cdot d\right)}}{\sqrt{c \cdot c + d \cdot d} \cdot \sqrt{c \cdot c + d \cdot d}}\]
    5. Applied times-frac33.3

      \[\leadsto \color{blue}{\frac{1}{\sqrt{c \cdot c + d \cdot d}} \cdot \frac{b \cdot c - a \cdot d}{\sqrt{c \cdot c + d \cdot d}}}\]
    6. Simplified33.3

      \[\leadsto \color{blue}{\frac{1}{\sqrt{c^2 + d^2}^*}} \cdot \frac{b \cdot c - a \cdot d}{\sqrt{c \cdot c + d \cdot d}}\]
    7. Simplified26.4

      \[\leadsto \frac{1}{\sqrt{c^2 + d^2}^*} \cdot \color{blue}{\frac{b \cdot c - a \cdot d}{\sqrt{c^2 + d^2}^*}}\]
    8. Using strategy rm
    9. Applied associate-*l/26.3

      \[\leadsto \color{blue}{\frac{1 \cdot \frac{b \cdot c - a \cdot d}{\sqrt{c^2 + d^2}^*}}{\sqrt{c^2 + d^2}^*}}\]
    10. Simplified26.3

      \[\leadsto \frac{\color{blue}{\frac{c \cdot b - a \cdot d}{\sqrt{c^2 + d^2}^*}}}{\sqrt{c^2 + d^2}^*}\]
    11. Using strategy rm
    12. Applied div-sub26.3

      \[\leadsto \frac{\color{blue}{\frac{c \cdot b}{\sqrt{c^2 + d^2}^*} - \frac{a \cdot d}{\sqrt{c^2 + d^2}^*}}}{\sqrt{c^2 + d^2}^*}\]
    13. Using strategy rm
    14. Applied *-un-lft-identity26.3

      \[\leadsto \frac{\frac{c \cdot b}{\sqrt{c^2 + d^2}^*} - \frac{a \cdot d}{\color{blue}{1 \cdot \sqrt{c^2 + d^2}^*}}}{\sqrt{c^2 + d^2}^*}\]
    15. Applied times-frac9.0

      \[\leadsto \frac{\frac{c \cdot b}{\sqrt{c^2 + d^2}^*} - \color{blue}{\frac{a}{1} \cdot \frac{d}{\sqrt{c^2 + d^2}^*}}}{\sqrt{c^2 + d^2}^*}\]
    16. Simplified9.0

      \[\leadsto \frac{\frac{c \cdot b}{\sqrt{c^2 + d^2}^*} - \color{blue}{a} \cdot \frac{d}{\sqrt{c^2 + d^2}^*}}{\sqrt{c^2 + d^2}^*}\]

    if -3.033774745784645e+77 < a < 2.753179196369121e+48

    1. Initial program 21.4

      \[\frac{b \cdot c - a \cdot d}{c \cdot c + d \cdot d}\]
    2. Using strategy rm
    3. Applied add-sqr-sqrt21.4

      \[\leadsto \frac{b \cdot c - a \cdot d}{\color{blue}{\sqrt{c \cdot c + d \cdot d} \cdot \sqrt{c \cdot c + d \cdot d}}}\]
    4. Applied *-un-lft-identity21.4

      \[\leadsto \frac{\color{blue}{1 \cdot \left(b \cdot c - a \cdot d\right)}}{\sqrt{c \cdot c + d \cdot d} \cdot \sqrt{c \cdot c + d \cdot d}}\]
    5. Applied times-frac21.4

      \[\leadsto \color{blue}{\frac{1}{\sqrt{c \cdot c + d \cdot d}} \cdot \frac{b \cdot c - a \cdot d}{\sqrt{c \cdot c + d \cdot d}}}\]
    6. Simplified21.4

      \[\leadsto \color{blue}{\frac{1}{\sqrt{c^2 + d^2}^*}} \cdot \frac{b \cdot c - a \cdot d}{\sqrt{c \cdot c + d \cdot d}}\]
    7. Simplified10.5

      \[\leadsto \frac{1}{\sqrt{c^2 + d^2}^*} \cdot \color{blue}{\frac{b \cdot c - a \cdot d}{\sqrt{c^2 + d^2}^*}}\]
    8. Using strategy rm
    9. Applied associate-*l/10.3

      \[\leadsto \color{blue}{\frac{1 \cdot \frac{b \cdot c - a \cdot d}{\sqrt{c^2 + d^2}^*}}{\sqrt{c^2 + d^2}^*}}\]
    10. Simplified10.3

      \[\leadsto \frac{\color{blue}{\frac{c \cdot b - a \cdot d}{\sqrt{c^2 + d^2}^*}}}{\sqrt{c^2 + d^2}^*}\]
    11. Using strategy rm
    12. Applied div-sub10.3

      \[\leadsto \frac{\color{blue}{\frac{c \cdot b}{\sqrt{c^2 + d^2}^*} - \frac{a \cdot d}{\sqrt{c^2 + d^2}^*}}}{\sqrt{c^2 + d^2}^*}\]
    13. Using strategy rm
    14. Applied associate-/l*2.4

      \[\leadsto \frac{\color{blue}{\frac{c}{\frac{\sqrt{c^2 + d^2}^*}{b}}} - \frac{a \cdot d}{\sqrt{c^2 + d^2}^*}}{\sqrt{c^2 + d^2}^*}\]
  3. Recombined 2 regimes into one program.
  4. Final simplification4.8

    \[\leadsto \begin{array}{l} \mathbf{if}\;a \le -3.033774745784645 \cdot 10^{+77} \lor \neg \left(a \le 2.753179196369121 \cdot 10^{+48}\right):\\ \;\;\;\;\frac{\frac{c \cdot b}{\sqrt{c^2 + d^2}^*} - \frac{d}{\sqrt{c^2 + d^2}^*} \cdot a}{\sqrt{c^2 + d^2}^*}\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{c}{\frac{\sqrt{c^2 + d^2}^*}{b}} - \frac{a \cdot d}{\sqrt{c^2 + d^2}^*}}{\sqrt{c^2 + d^2}^*}\\ \end{array}\]

Runtime

Time bar (total: 47.4s)Debug logProfile

herbie shell --seed 2018230 +o rules:numerics
(FPCore (a b c d)
  :name "Complex division, imag part"

  :herbie-target
  (if (< (fabs d) (fabs c)) (/ (- b (* a (/ d c))) (+ c (* d (/ d c)))) (/ (+ (- a) (* b (/ c d))) (+ d (* c (/ c d)))))

  (/ (- (* b c) (* a d)) (+ (* c c) (* d d))))