Average Error: 30.5 → 17.8
Time: 7.8s
Precision: 64
Internal Precision: 576
\[\log \left(\sqrt{re \cdot re + im \cdot im}\right)\]
\[\begin{array}{l} \mathbf{if}\;re \le -4.9066085980367 \cdot 10^{+122}:\\ \;\;\;\;\log \left(-re\right)\\ \mathbf{if}\;re \le -1.4664875883069754 \cdot 10^{-130}:\\ \;\;\;\;\log \left(\sqrt{re \cdot re + im \cdot im}\right)\\ \mathbf{if}\;re \le -3.5689365038231576 \cdot 10^{-250}:\\ \;\;\;\;\log im\\ \mathbf{if}\;re \le 5.78951180277367 \cdot 10^{+88}:\\ \;\;\;\;\log \left(\sqrt{re \cdot re + im \cdot im}\right)\\ \mathbf{else}:\\ \;\;\;\;\log re\\ \end{array}\]

Error

Bits error versus re

Bits error versus im

Derivation

  1. Split input into 4 regimes
  2. if re < -4.9066085980367e+122

    1. Initial program 54.6

      \[\log \left(\sqrt{re \cdot re + im \cdot im}\right)\]
    2. Taylor expanded around -inf 7.7

      \[\leadsto \log \color{blue}{\left(-1 \cdot re\right)}\]
    3. Applied simplify7.7

      \[\leadsto \color{blue}{\log \left(-re\right)}\]

    if -4.9066085980367e+122 < re < -1.4664875883069754e-130 or -3.5689365038231576e-250 < re < 5.78951180277367e+88

    1. Initial program 19.8

      \[\log \left(\sqrt{re \cdot re + im \cdot im}\right)\]

    if -1.4664875883069754e-130 < re < -3.5689365038231576e-250

    1. Initial program 26.6

      \[\log \left(\sqrt{re \cdot re + im \cdot im}\right)\]
    2. Taylor expanded around 0 35.4

      \[\leadsto \log \color{blue}{im}\]

    if 5.78951180277367e+88 < re

    1. Initial program 47.6

      \[\log \left(\sqrt{re \cdot re + im \cdot im}\right)\]
    2. Taylor expanded around inf 9.0

      \[\leadsto \log \color{blue}{re}\]
  3. Recombined 4 regimes into one program.

Runtime

Time bar (total: 7.8s)Debug logProfile

herbie shell --seed '#(1072330854 3074818769 591214268 3603999196 3863745332 3332387116)' 
(FPCore (re im)
  :name "math.log/1 on complex, real part"
  (log (sqrt (+ (* re re) (* im im)))))