Average Error: 14.2 → 0.4
Time: 39.3s
Precision: 64
Internal Precision: 128
\[\frac{1}{x + 1} - \frac{1}{x - 1}\]
\[\frac{1}{(x \cdot x + -1)_*} \cdot -2\]

Error

Bits error versus x

Derivation

  1. Initial program 14.2

    \[\frac{1}{x + 1} - \frac{1}{x - 1}\]
  2. Using strategy rm
  3. Applied flip--29.0

    \[\leadsto \frac{1}{x + 1} - \frac{1}{\color{blue}{\frac{x \cdot x - 1 \cdot 1}{x + 1}}}\]
  4. Applied associate-/r/29.0

    \[\leadsto \frac{1}{x + 1} - \color{blue}{\frac{1}{x \cdot x - 1 \cdot 1} \cdot \left(x + 1\right)}\]
  5. Applied flip-+14.2

    \[\leadsto \frac{1}{\color{blue}{\frac{x \cdot x - 1 \cdot 1}{x - 1}}} - \frac{1}{x \cdot x - 1 \cdot 1} \cdot \left(x + 1\right)\]
  6. Applied associate-/r/14.2

    \[\leadsto \color{blue}{\frac{1}{x \cdot x - 1 \cdot 1} \cdot \left(x - 1\right)} - \frac{1}{x \cdot x - 1 \cdot 1} \cdot \left(x + 1\right)\]
  7. Applied distribute-lft-out--13.6

    \[\leadsto \color{blue}{\frac{1}{x \cdot x - 1 \cdot 1} \cdot \left(\left(x - 1\right) - \left(x + 1\right)\right)}\]
  8. Simplified13.6

    \[\leadsto \color{blue}{\frac{1}{(x \cdot x + -1)_*}} \cdot \left(\left(x - 1\right) - \left(x + 1\right)\right)\]
  9. Simplified0.4

    \[\leadsto \frac{1}{(x \cdot x + -1)_*} \cdot \color{blue}{-2}\]
  10. Final simplification0.4

    \[\leadsto \frac{1}{(x \cdot x + -1)_*} \cdot -2\]

Reproduce

herbie shell --seed 2018362 +o rules:numerics
(FPCore (x)
  :name "Asymptote A"
  (- (/ 1 (+ x 1)) (/ 1 (- x 1))))

Details

Time bar (total: 34.5s)Debug log

start88.0ms

Algorithm
intervals

setup26.0ms

Pruning

1 alts after pruning (1 fresh and 0 done)

Merged error: 10.6b

localize25.0ms

Local error

Found 3 expressions with local error:

1.6b
(- (/ 1 (+ x 1)) (/ 1 (- x 1)))
0.0b
(/ 1 (- x 1))
0.0b
(/ 1 (+ x 1))

rewrite18.0ms

Algorithm
rewrite-expression-head
Counts
3 → 103
Calls

3 calls. Slowest were:

12.0ms
(- (/ 1 (+ x 1)) (/ 1 (- x 1)))
2.0ms
(/ 1 (- x 1))
2.0ms
(/ 1 (+ x 1))

series82.0ms

Counts
3 → 9
Calls

3 calls. Slowest were:

60.0ms
(- (/ 1 (+ x 1)) (/ 1 (- x 1)))
11.0ms
(/ 1 (- x 1))
10.0ms
(/ 1 (+ x 1))

simplify20.3s

Counts
108 → 112
Calls

108 calls. Slowest were:

1.3s
(fma (- (+ x 1)) (/ 1 (- (* x x) (* 1 1))) (* (+ x 1) (/ 1 (- (* x x) (* 1 1)))))
1.3s
(fma (- (+ x 1)) (/ 1 (- (* x x) (* 1 1))) (* (+ x 1) (/ 1 (- (* x x) (* 1 1)))))
1.2s
(fma (- (+ x 1)) (/ 1 (- (* x x) (* 1 1))) (* (+ x 1) (/ 1 (- (* x x) (* 1 1)))))

prune940.0ms

Pruning

3 alts after pruning (3 fresh and 0 done)

Merged error: 0.1b

localize10.0ms

Local error

Found 2 expressions with local error:

0.1b
(/ 1 (fma x x -1))
0.0b
(* (/ 1 (fma x x -1)) -2)

rewrite7.0ms

Algorithm
rewrite-expression-head
Counts
2 → 33
Calls

2 calls. Slowest were:

5.0ms
(* (/ 1 (fma x x -1)) -2)
1.0ms
(/ 1 (fma x x -1))

series36.0ms

Counts
2 → 6
Calls

2 calls. Slowest were:

21.0ms
(/ 1 (fma x x -1))
15.0ms
(* (/ 1 (fma x x -1)) -2)

simplify2.0s

Counts
13 → 39
Calls

13 calls. Slowest were:

886.0ms
(- (+ (* 2 (/ 1 (pow x 4))) (+ (* 2 (/ 1 (pow x 6))) (* 2 (/ 1 (pow x 2))))))
760.0ms
(- (+ (* 2 (/ 1 (pow x 4))) (+ (* 2 (/ 1 (pow x 6))) (* 2 (/ 1 (pow x 2))))))
133.0ms
(+ (* 2 (pow x 2)) (+ (* 2 (pow x 4)) 2))

prune409.0ms

Pruning

5 alts after pruning (4 fresh and 1 done)

Merged error: 0.1b

localize18.0ms

Local error

Found 4 expressions with local error:

13.9b
(cbrt (* (/ 1 (fma x x -1)) -2))
13.9b
(cbrt (* (/ 1 (fma x x -1)) -2))
13.9b
(cbrt (* (/ 1 (fma x x -1)) -2))
0.1b
(* (cbrt (* (/ 1 (fma x x -1)) -2)) (cbrt (* (/ 1 (fma x x -1)) -2)))

rewrite23.0ms

Algorithm
rewrite-expression-head
Counts
4 → 65
Calls

4 calls. Slowest were:

12.0ms
(* (cbrt (* (/ 1 (fma x x -1)) -2)) (cbrt (* (/ 1 (fma x x -1)) -2)))
4.0ms
(cbrt (* (/ 1 (fma x x -1)) -2))
3.0ms
(cbrt (* (/ 1 (fma x x -1)) -2))

series771.0ms

Counts
4 → 12
Calls

4 calls. Slowest were:

219.0ms
(* (cbrt (* (/ 1 (fma x x -1)) -2)) (cbrt (* (/ 1 (fma x x -1)) -2)))
214.0ms
(cbrt (* (/ 1 (fma x x -1)) -2))
169.0ms
(cbrt (* (/ 1 (fma x x -1)) -2))
168.0ms
(cbrt (* (/ 1 (fma x x -1)) -2))

simplify4.2s

Counts
38 → 77
Calls

38 calls. Slowest were:

365.0ms
(+ (* 5/9 (* (pow (/ 1 (pow x 16)) 1/3) (pow (cbrt -2) 2))) (+ (* 2/3 (* (pow (/ 1 (pow x 10)) 1/3) (pow (cbrt -2) 2))) (* (pow (/ 1 (pow x 4)) 1/3) (pow (cbrt -2) 2))))
348.0ms
(+ (* 2/3 (* (pow x 2) (pow (cbrt -2) 2))) (+ (pow (cbrt -2) 2) (* 5/9 (* (pow x 4) (pow (cbrt -2) 2)))))
310.0ms
(+ (* 5/9 (* (pow (/ 1 (pow x 16)) 1/3) (pow (cbrt -2) 2))) (+ (* 2/3 (* (pow (/ 1 (pow x 10)) 1/3) (pow (cbrt -2) 2))) (* (pow (/ 1 (pow x 4)) 1/3) (pow (cbrt -2) 2))))

prune1.1s

Pruning

5 alts after pruning (3 fresh and 2 done)

Merged error: 0.1b

localize8.0ms

Local error

Found 4 expressions with local error:

8.2b
(cbrt (* (* (* (/ 1 (fma x x -1)) -2) (* (/ 1 (fma x x -1)) -2)) (* (/ 1 (fma x x -1)) -2)))
0.1b
(/ 1 (fma x x -1))
0.1b
(/ 1 (fma x x -1))
0.1b
(/ 1 (fma x x -1))

rewrite36.0ms

Algorithm
rewrite-expression-head
Counts
4 → 73
Calls

4 calls. Slowest were:

30.0ms
(cbrt (* (* (* (/ 1 (fma x x -1)) -2) (* (/ 1 (fma x x -1)) -2)) (* (/ 1 (fma x x -1)) -2)))
1.0ms
(/ 1 (fma x x -1))
1.0ms
(/ 1 (fma x x -1))

series163.0ms

Counts
4 → 12
Calls

4 calls. Slowest were:

90.0ms
(cbrt (* (* (* (/ 1 (fma x x -1)) -2) (* (/ 1 (fma x x -1)) -2)) (* (/ 1 (fma x x -1)) -2)))
25.0ms
(/ 1 (fma x x -1))
25.0ms
(/ 1 (fma x x -1))
23.0ms
(/ 1 (fma x x -1))

simplify3.0s

Counts
33 → 85
Calls

33 calls. Slowest were:

757.0ms
(cbrt (* (* (* (/ 1 (fma x x -1)) -2) (* 1 -2)) (* (/ 1 (fma x x -1)) -2)))
668.0ms
(cbrt (* (* (* (/ 1 (fma x x -1)) -2) (* (/ 1 (fma x x -1)) -2)) (* 1 -2)))
281.0ms
(cbrt (* (* (/ 1 (fma x x -1)) -2) (* (/ 1 (fma x x -1)) -2)))

prune1.2s

Pruning

5 alts after pruning (2 fresh and 3 done)

Merged error: 0.1b

regimes71.0ms

Accuracy

0% (0.1b remaining)

Error of 0.4b against oracle of 0.4b and baseline of 0.4b

bsearch2.0ms