Average Error: 29.3 → 0.0
Time: 16.9s
Precision: 64
Internal Precision: 128
\[\log \left(N + 1\right) - \log N\]
\[\begin{array}{l} \mathbf{if}\;N \le 9955.673000070075:\\ \;\;\;\;\log \left(\frac{1 + N}{N}\right)\\ \mathbf{else}:\\ \;\;\;\;\frac{1}{N} - \frac{1}{N \cdot N} \cdot \left(\frac{1}{2} - \frac{\frac{1}{3}}{N}\right)\\ \end{array}\]

Error

Bits error versus N

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Derivation

  1. Split input into 2 regimes
  2. if N < 9955.673000070075

    1. Initial program 0.1

      \[\log \left(N + 1\right) - \log N\]
    2. Using strategy rm
    3. Applied diff-log0.1

      \[\leadsto \color{blue}{\log \left(\frac{N + 1}{N}\right)}\]

    if 9955.673000070075 < N

    1. Initial program 59.5

      \[\log \left(N + 1\right) - \log N\]
    2. Taylor expanded around inf 0.0

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

      \[\leadsto \color{blue}{\frac{1}{N} - \frac{1}{N \cdot N} \cdot \left(\frac{1}{2} - \frac{\frac{1}{3}}{N}\right)}\]
  3. Recombined 2 regimes into one program.
  4. Final simplification0.0

    \[\leadsto \begin{array}{l} \mathbf{if}\;N \le 9955.673000070075:\\ \;\;\;\;\log \left(\frac{1 + N}{N}\right)\\ \mathbf{else}:\\ \;\;\;\;\frac{1}{N} - \frac{1}{N \cdot N} \cdot \left(\frac{1}{2} - \frac{\frac{1}{3}}{N}\right)\\ \end{array}\]

Reproduce

herbie shell --seed 2019007 
(FPCore (N)
  :name "2log (problem 3.3.6)"
  (- (log (+ N 1)) (log N)))

Details

Time bar (total: 16.5s)Debug log

sample105.0ms

Algorithm
intervals

simplify9.0ms

Counts
1 → 1
Calls

1 calls. Slowest were:

9.0ms
(- (log (+ N 1)) (log N))

prune31.0ms

Pruning

1 alts after pruning (1 fresh and 0 done)

Merged error: 33.0b

localize27.0ms

Local error

Found 2 expressions with local error:

2.9b
(- (log (+ N 1)) (log N))
2.7b
(log (+ N 1))

rewrite12.0ms

Algorithm
rewrite-expression-head
Counts
2 → 34
Calls

2 calls. Slowest were:

9.0ms
(- (log (+ N 1)) (log N))
2.0ms
(log (+ N 1))

series126.0ms

Counts
2 → 6
Calls

2 calls. Slowest were:

93.0ms
(- (log (+ N 1)) (log N))
33.0ms
(log (+ N 1))

simplify934.0ms

Counts
22 → 40
Calls

22 calls. Slowest were:

227.0ms
(- (+ (/ 1 N) (log -1)) (+ (* 1/2 (/ 1 (pow N 2))) (log (/ -1 N))))
165.0ms
(- (+ (* 1/3 (/ 1 (pow N 3))) (/ 1 N)) (* 1/2 (/ 1 (pow N 2))))
145.0ms
(- (/ 1 N) (+ (* 1/2 (/ 1 (pow N 2))) (log (/ 1 N))))

prune358.0ms

Pruning

2 alts after pruning (2 fresh and 0 done)

Merged error: 0.0b

localize18.0ms

Local error

Found 4 expressions with local error:

0.4b
(/ 1 (* N N))
0.4b
(/ 1/3 N)
0.0b
(* (/ 1 (* N N)) (- 1/2 (/ 1/3 N)))
0.0b
(- (/ 1 N) (* (/ 1 (* N N)) (- 1/2 (/ 1/3 N))))

rewrite22.0ms

Algorithm
rewrite-expression-head
Counts
4 → 74
Calls

4 calls. Slowest were:

11.0ms
(- (/ 1 N) (* (/ 1 (* N N)) (- 1/2 (/ 1/3 N))))
8.0ms
(* (/ 1 (* N N)) (- 1/2 (/ 1/3 N)))
1.0ms
(/ 1 (* N N))

series96.0ms

Counts
4 → 12
Calls

4 calls. Slowest were:

51.0ms
(* (/ 1 (* N N)) (- 1/2 (/ 1/3 N)))
19.0ms
(- (/ 1 N) (* (/ 1 (* N N)) (- 1/2 (/ 1/3 N))))
13.0ms
(/ 1 (* N N))
12.0ms
(/ 1/3 N)

simplify7.1s

Counts
49 → 86
Calls

49 calls. Slowest were:

475.0ms
(* (- (/ 1/3 N)) (/ 1 (* N N)))
436.0ms
(* (/ 1 (* N N)) (- (/ 1/3 N)))
430.0ms
(* (- (/ 1/3 N)) (/ 1 (* N N)))

prune695.0ms

Pruning

3 alts after pruning (2 fresh and 1 done)

Merged error: 0.0b

localize11.0ms

Local error

Found 2 expressions with local error:

3.3b
(log (/ (+ N 1) N))
0.0b
(/ (+ N 1) N)

rewrite9.0ms

Algorithm
rewrite-expression-head
Counts
2 → 29
Calls

2 calls. Slowest were:

7.0ms
(/ (+ N 1) N)
2.0ms
(log (/ (+ N 1) N))

series55.0ms

Counts
2 → 6
Calls

2 calls. Slowest were:

36.0ms
(log (/ (+ N 1) N))
19.0ms
(/ (+ N 1) N)

simplify403.0ms

Counts
16 → 35
Calls

16 calls. Slowest were:

137.0ms
(- (+ (* 1/3 (/ 1 (pow N 3))) (/ 1 N)) (* 1/2 (/ 1 (pow N 2))))
134.0ms
(- (+ (* 1/3 (/ 1 (pow N 3))) (/ 1 N)) (* 1/2 (/ 1 (pow N 2))))
81.0ms
(- N (+ (log N) (* 1/2 (pow N 2))))

prune272.0ms

Pruning

4 alts after pruning (2 fresh and 2 done)

Merged error: 0.0b

localize8.0ms

Local error

Found 4 expressions with local error:

3.3b
(log (/ (+ N 1) N))
3.3b
(log (/ (+ N 1) N))
3.3b
(log (/ (+ N 1) N))
0.3b
(* (cbrt (log (/ (+ N 1) N))) (cbrt (log (/ (+ N 1) N))))

rewrite10.0ms

Algorithm
rewrite-expression-head
Counts
4 → 72
Calls

4 calls. Slowest were:

6.0ms
(* (cbrt (log (/ (+ N 1) N))) (cbrt (log (/ (+ N 1) N))))
1.0ms
(log (/ (+ N 1) N))
1.0ms
(log (/ (+ N 1) N))

series233.0ms

Counts
4 → 12
Calls

4 calls. Slowest were:

99.0ms
(* (cbrt (log (/ (+ N 1) N))) (cbrt (log (/ (+ N 1) N))))
51.0ms
(log (/ (+ N 1) N))
46.0ms
(log (/ (+ N 1) N))
36.0ms
(log (/ (+ N 1) N))

simplify1.7s

Counts
52 → 84
Calls

52 calls. Slowest were:

333.0ms
(- (+ (pow (pow (log N) 2) 1/3) (* 1/3 (* (pow N 2) (pow (/ 1 (log N)) 1/3)))) (+ (* 2/3 (* (pow (/ 1 (log N)) 1/3) N)) (* 1/9 (* (pow N 2) (pow (/ 1 (pow (log N) 4)) 1/3)))))
150.0ms
(- (+ (* 1/3 (/ 1 (pow N 3))) (/ 1 N)) (* 1/2 (/ 1 (pow N 2))))
144.0ms
(- (+ (* 1/3 (/ 1 (pow N 3))) (/ 1 N)) (* 1/2 (/ 1 (pow N 2))))

prune762.0ms

Pruning

4 alts after pruning (2 fresh and 2 done)

Merged error: 0.0b

regimes42.0ms

Accuracy

100% (0.0b remaining)

Error of 0.0b against oracle of 0.0b and baseline of 31.0b

bsearch50.0ms

end0.0ms

sample3.4s

Algorithm
intervals