Average Error: 15.1 → 0.8
Time: 7.9s
Precision: 64
Internal Precision: 128
\[\tan^{-1} \left(N + 1\right) - \tan^{-1} N\]
↓
\[(e^{\log_* (1 + \tan^{-1}_* \frac{1}{(N \cdot \left(N + 1\right) + 1)_*})} - 1)^*\]

Error

Bits error versus N

Target

Original15.1
Target0.3
Herbie0.8
\[\tan^{-1} \left(\frac{1}{1 + N \cdot \left(N + 1\right)}\right)\]

Derivation

  1. Initial program 15.1

    \[\tan^{-1} \left(N + 1\right) - \tan^{-1} N\]

  2. Initial simplification15.1

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

  4. Applied diff-atan14.1

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

  5. Simplified0.3

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

  6. Simplified0.3

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

  8. Applied expm1-log1p-u0.8

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

  9. Final simplification0.8

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

Runtime

Time bar (total: 7.9s)Debug logProfile

herbie shell --seed 2018277 +o rules:numerics
(FPCore (N)
  :name "2atan (example 3.5)"

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

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