Average Error: 36.9 → 13.0
Time: 18.4s
Precision: 64
Internal Precision: 128
\[0.5 \cdot \sqrt{2.0 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}\]
\[0.5 \cdot {\left((\left(\sqrt{re^2 + im^2}^*\right) \cdot 2.0 + \left(re \cdot 2.0\right))_*\right)}^{\frac{1}{2}}\]

Error

Bits error versus re

Bits error versus im

Target

Original36.9
Target32.3
Herbie13.0
\[\begin{array}{l} \mathbf{if}\;re \lt 0:\\ \;\;\;\;0.5 \cdot \left(\sqrt{2} \cdot \sqrt{\frac{im \cdot im}{\sqrt{re \cdot re + im \cdot im} - re}}\right)\\ \mathbf{else}:\\ \;\;\;\;0.5 \cdot \sqrt{2.0 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}\\ \end{array}\]

Derivation

  1. Initial program 36.9

    \[0.5 \cdot \sqrt{2.0 \cdot \left(\sqrt{re \cdot re + im \cdot im} + re\right)}\]
  2. Initial simplification13.0

    \[\leadsto 0.5 \cdot \sqrt{(\left(\sqrt{re^2 + im^2}^*\right) \cdot 2.0 + \left(re \cdot 2.0\right))_*}\]
  3. Using strategy rm
  4. Applied add-sqr-sqrt13.0

    \[\leadsto 0.5 \cdot \sqrt{\color{blue}{\sqrt{(\left(\sqrt{re^2 + im^2}^*\right) \cdot 2.0 + \left(re \cdot 2.0\right))_*} \cdot \sqrt{(\left(\sqrt{re^2 + im^2}^*\right) \cdot 2.0 + \left(re \cdot 2.0\right))_*}}}\]
  5. Applied sqrt-prod13.4

    \[\leadsto 0.5 \cdot \color{blue}{\left(\sqrt{\sqrt{(\left(\sqrt{re^2 + im^2}^*\right) \cdot 2.0 + \left(re \cdot 2.0\right))_*}} \cdot \sqrt{\sqrt{(\left(\sqrt{re^2 + im^2}^*\right) \cdot 2.0 + \left(re \cdot 2.0\right))_*}}\right)}\]
  6. Using strategy rm
  7. Applied pow1/213.4

    \[\leadsto 0.5 \cdot \left(\sqrt{\sqrt{(\left(\sqrt{re^2 + im^2}^*\right) \cdot 2.0 + \left(re \cdot 2.0\right))_*}} \cdot \color{blue}{{\left(\sqrt{(\left(\sqrt{re^2 + im^2}^*\right) \cdot 2.0 + \left(re \cdot 2.0\right))_*}\right)}^{\frac{1}{2}}}\right)\]
  8. Applied pow1/213.4

    \[\leadsto 0.5 \cdot \left(\color{blue}{{\left(\sqrt{(\left(\sqrt{re^2 + im^2}^*\right) \cdot 2.0 + \left(re \cdot 2.0\right))_*}\right)}^{\frac{1}{2}}} \cdot {\left(\sqrt{(\left(\sqrt{re^2 + im^2}^*\right) \cdot 2.0 + \left(re \cdot 2.0\right))_*}\right)}^{\frac{1}{2}}\right)\]
  9. Applied pow-prod-down13.0

    \[\leadsto 0.5 \cdot \color{blue}{{\left(\sqrt{(\left(\sqrt{re^2 + im^2}^*\right) \cdot 2.0 + \left(re \cdot 2.0\right))_*} \cdot \sqrt{(\left(\sqrt{re^2 + im^2}^*\right) \cdot 2.0 + \left(re \cdot 2.0\right))_*}\right)}^{\frac{1}{2}}}\]
  10. Simplified13.0

    \[\leadsto 0.5 \cdot {\color{blue}{\left((\left(\sqrt{re^2 + im^2}^*\right) \cdot 2.0 + \left(2.0 \cdot re\right))_*\right)}}^{\frac{1}{2}}\]
  11. Final simplification13.0

    \[\leadsto 0.5 \cdot {\left((\left(\sqrt{re^2 + im^2}^*\right) \cdot 2.0 + \left(re \cdot 2.0\right))_*\right)}^{\frac{1}{2}}\]

Runtime

Time bar (total: 18.4s)Debug logProfile

herbie shell --seed 2018336 +o rules:numerics
(FPCore (re im)
  :name "math.sqrt on complex, real part"

  :herbie-target
  (if (< re 0) (* 0.5 (* (sqrt 2) (sqrt (/ (* im im) (- (sqrt (+ (* re re) (* im im))) re))))) (* 0.5 (sqrt (* 2.0 (+ (sqrt (+ (* re re) (* im im))) re)))))

  (* 0.5 (sqrt (* 2.0 (+ (sqrt (+ (* re re) (* im im))) re)))))