Average Error: 63.0 → 0
Time: 28.9s
Precision: 64
Internal Precision: 1344
\[\left(\left(n + 1\right) \cdot \log \left(n + 1\right) - n \cdot \log n\right) - 1\]
↓
\[\left(\log n - \frac{\frac{\frac{1}{6}}{n}}{n}\right) + \frac{\frac{1}{2}}{n}\]

Error

Bits error versus n

Target

Original63.0
Target0
Herbie0
\[\log \left(n + 1\right) - \left(\frac{1}{2 \cdot n} - \left(\frac{1}{3 \cdot \left(n \cdot n\right)} - \frac{4}{{n}^{3}}\right)\right)\]

Derivation

  1. Initial program 63.0

    \[\left(\left(n + 1\right) \cdot \log \left(n + 1\right) - n \cdot \log n\right) - 1\]

  2. Taylor expanded around inf 0.0

    \[\leadsto \color{blue}{\left(\left(1 + \frac{1}{2} \cdot \frac{1}{n}\right) - \left(\log \left(\frac{1}{n}\right) + \frac{1}{6} \cdot \frac{1}{{n}^{2}}\right)\right)} - 1\]

  3. Applied simplify0

    \[\leadsto \color{blue}{\left(\log n - \frac{\frac{\frac{1}{6}}{n}}{n}\right) + \left(\frac{\frac{1}{2}}{n} + 0\right)}\]

  4. Applied simplify0

    \[\leadsto \left(\log n - \frac{\frac{\frac{1}{6}}{n}}{n}\right) + \color{blue}{\frac{\frac{1}{2}}{n}}\]

Runtime

Time bar (total: 28.9s)Debug logProfile

herbie shell --seed '#(1071373924 2949776965 1885069702 3247780810 90874544 2263903749)' 
(FPCore (n)
  :name "logs (example 3.8)"
  :pre (> n 6.8e+15)

  :herbie-target
  (- (log (+ n 1)) (- (/ 1 (* 2 n)) (- (/ 1 (* 3 (* n n))) (/ 4 (pow n 3)))))

  (- (- (* (+ n 1) (log (+ n 1))) (* n (log n))) 1))