Average Error: 25.8 → 0.5
Time: 28.9s
Precision: 64
Internal Precision: 128
\[\frac{b \cdot c - a \cdot d}{c \cdot c + d \cdot d}\]
\[\frac{\left(-a\right) \cdot \frac{d}{\sqrt{d^2 + c^2}^*} + b \cdot \left(\frac{1}{\sqrt{d^2 + c^2}^*} \cdot c\right)}{\sqrt{d^2 + c^2}^*}\]

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
Herbie0.5
\[\begin{array}{l} \mathbf{if}\;\left|d\right| \lt \left|c\right|:\\ \;\;\;\;\frac{b - a \cdot \frac{d}{c}}{c + d \cdot \frac{d}{c}}\\ \mathbf{else}:\\ \;\;\;\;\frac{\left(-a\right) + b \cdot \frac{c}{d}}{d + c \cdot \frac{c}{d}}\\ \end{array}\]

Derivation

  1. Initial program 25.8

    \[\frac{b \cdot c - a \cdot d}{c \cdot c + d \cdot d}\]
  2. Initial simplification25.8

    \[\leadsto \frac{b \cdot c - a \cdot d}{(d \cdot d + \left(c \cdot c\right))_*}\]
  3. Using strategy rm
  4. Applied add-sqr-sqrt25.8

    \[\leadsto \frac{b \cdot c - a \cdot d}{\color{blue}{\sqrt{(d \cdot d + \left(c \cdot c\right))_*} \cdot \sqrt{(d \cdot d + \left(c \cdot c\right))_*}}}\]
  5. Applied *-un-lft-identity25.8

    \[\leadsto \frac{\color{blue}{1 \cdot \left(b \cdot c - a \cdot d\right)}}{\sqrt{(d \cdot d + \left(c \cdot c\right))_*} \cdot \sqrt{(d \cdot d + \left(c \cdot c\right))_*}}\]
  6. Applied times-frac25.8

    \[\leadsto \color{blue}{\frac{1}{\sqrt{(d \cdot d + \left(c \cdot c\right))_*}} \cdot \frac{b \cdot c - a \cdot d}{\sqrt{(d \cdot d + \left(c \cdot c\right))_*}}}\]
  7. Simplified25.8

    \[\leadsto \color{blue}{\frac{1}{\sqrt{d^2 + c^2}^*}} \cdot \frac{b \cdot c - a \cdot d}{\sqrt{(d \cdot d + \left(c \cdot c\right))_*}}\]
  8. Simplified16.5

    \[\leadsto \frac{1}{\sqrt{d^2 + c^2}^*} \cdot \color{blue}{\frac{b \cdot c - a \cdot d}{\sqrt{d^2 + c^2}^*}}\]
  9. Using strategy rm
  10. Applied associate-*r/16.4

    \[\leadsto \color{blue}{\frac{\frac{1}{\sqrt{d^2 + c^2}^*} \cdot \left(b \cdot c - a \cdot d\right)}{\sqrt{d^2 + c^2}^*}}\]
  11. Using strategy rm
  12. Applied sub-neg16.4

    \[\leadsto \frac{\frac{1}{\sqrt{d^2 + c^2}^*} \cdot \color{blue}{\left(b \cdot c + \left(-a \cdot d\right)\right)}}{\sqrt{d^2 + c^2}^*}\]
  13. Applied distribute-rgt-in16.4

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

    \[\leadsto \frac{\left(b \cdot c\right) \cdot \frac{1}{\sqrt{d^2 + c^2}^*} + \color{blue}{a \cdot \frac{-d}{\sqrt{d^2 + c^2}^*}}}{\sqrt{d^2 + c^2}^*}\]
  15. Using strategy rm
  16. Applied associate-*l*0.5

    \[\leadsto \frac{\color{blue}{b \cdot \left(c \cdot \frac{1}{\sqrt{d^2 + c^2}^*}\right)} + a \cdot \frac{-d}{\sqrt{d^2 + c^2}^*}}{\sqrt{d^2 + c^2}^*}\]
  17. Final simplification0.5

    \[\leadsto \frac{\left(-a\right) \cdot \frac{d}{\sqrt{d^2 + c^2}^*} + b \cdot \left(\frac{1}{\sqrt{d^2 + c^2}^*} \cdot c\right)}{\sqrt{d^2 + c^2}^*}\]

Runtime

Time bar (total: 28.9s)Debug logProfile

BaselineHerbieOracleSpan%
Regimes0.50.50.00.50%
herbie shell --seed 2018352 +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))))