Average Error: 14.5 → 0.4
Time: 15.5s
Precision: 64
Internal precision: 1408
\[\tan^{-1} \left(N + 1\right) - \tan^{-1} N\]
⬇
\[\tan^{-1}_* \frac{1 + 0}{\left(N + 1\right) \cdot N + 1}\]

Error

Bits error versus N

Target

Original14.5
Comparison0.4
Herbie0.4
\[ \tan^{-1} \left(\frac{1}{1 + N \cdot \left(N + 1\right)}\right) \]

Derivation

  1. Initial program 14.5

    \[\tan^{-1} \left(N + 1\right) - \tan^{-1} N\]
  2. Using strategy rm

  3. Applied diff-atan 13.4

    \[\leadsto \color{blue}{\tan^{-1}_* \frac{\left(N + 1\right) - N}{1 + \left(N + 1\right) \cdot N}}\]

  4. Applied simplify 0.4

    \[\leadsto \tan^{-1}_* \frac{\color{blue}{1 + 0}}{1 + \left(N + 1\right) \cdot N}\]

  5. Applied simplify 0.4

    \[\leadsto \tan^{-1}_* \frac{1 + 0}{\color{blue}{\left({N}^2 + N\right) + 1}}\]
  6. Using strategy rm

  7. Applied square-mult 0.4

    \[\leadsto \tan^{-1}_* \frac{1 + 0}{\left(\color{blue}{N \cdot N} + N\right) + 1}\]

  8. Applied distribute-lft1-in 0.4

    \[\leadsto \tan^{-1}_* \frac{1 + 0}{\color{blue}{\left(N + 1\right) \cdot N} + 1}\]
  9. Removed slow pow expressions

Runtime

Time bar (total: 15.5s) Debug log

Please include this information when filing a bug report:

herbie shell --seed '#(772101555 1905824529 294602591 2478279198 2123125427 4197813737)'
(FPCore (N)
  :name "2atan (example 3.5)"

  :target
  (atan (/ 1 (+ 1 (* N (+ N 1)))))

  (- (atan (+ N 1)) (atan N)))