Average Error: 29.8 → 0.1
Time: 17.7s
Precision: 64
Internal Precision: 128
\[\log \left(N + 1\right) - \log N\]
\[\begin{array}{l} \mathbf{if}\;N \le 5681.225756705843:\\ \;\;\;\;(\left(\sqrt{\log_* (1 + N)}\right) \cdot \left(\sqrt{\log_* (1 + N)}\right) + \left(-\log N\right))_*\\ \mathbf{else}:\\ \;\;\;\;(\left(\frac{1}{N \cdot N}\right) \cdot \left(\frac{\frac{1}{3}}{N} - \frac{1}{2}\right) + \left(\frac{1}{N}\right))_*\\ \end{array}\]

Error

Bits error versus N

Derivation

  1. Split input into 2 regimes
  2. if N < 5681.225756705843

    1. Initial program 0.1

      \[\log \left(N + 1\right) - \log N\]
    2. Initial simplification0.1

      \[\leadsto \log_* (1 + N) - \log N\]
    3. Using strategy rm
    4. Applied add-sqr-sqrt0.1

      \[\leadsto \color{blue}{\sqrt{\log_* (1 + N)} \cdot \sqrt{\log_* (1 + N)}} - \log N\]
    5. Applied fma-neg0.1

      \[\leadsto \color{blue}{(\left(\sqrt{\log_* (1 + N)}\right) \cdot \left(\sqrt{\log_* (1 + N)}\right) + \left(-\log N\right))_*}\]

    if 5681.225756705843 < N

    1. Initial program 59.6

      \[\log \left(N + 1\right) - \log N\]
    2. Initial simplification59.6

      \[\leadsto \log_* (1 + N) - \log N\]
    3. Taylor expanded around -inf 0.0

      \[\leadsto \color{blue}{\left(\frac{1}{3} \cdot \frac{1}{{N}^{3}} + \frac{1}{N}\right) - \frac{1}{2} \cdot \frac{1}{{N}^{2}}}\]
    4. Simplified0.0

      \[\leadsto \color{blue}{(\left(\frac{1}{N \cdot N}\right) \cdot \left(\frac{\frac{1}{3}}{N} - \frac{1}{2}\right) + \left(\frac{1}{N}\right))_*}\]
  3. Recombined 2 regimes into one program.
  4. Final simplification0.1

    \[\leadsto \begin{array}{l} \mathbf{if}\;N \le 5681.225756705843:\\ \;\;\;\;(\left(\sqrt{\log_* (1 + N)}\right) \cdot \left(\sqrt{\log_* (1 + N)}\right) + \left(-\log N\right))_*\\ \mathbf{else}:\\ \;\;\;\;(\left(\frac{1}{N \cdot N}\right) \cdot \left(\frac{\frac{1}{3}}{N} - \frac{1}{2}\right) + \left(\frac{1}{N}\right))_*\\ \end{array}\]

Runtime

Time bar (total: 17.7s)Debug logProfile

BaselineHerbieOracleSpan%
Regimes30.60.10.130.599.9%
herbie shell --seed 2018353 +o rules:numerics
(FPCore (N)
  :name "2log (problem 3.3.6)"
  (- (log (+ N 1)) (log N)))