Average Error: 29.6 → 0.6
Time: 12.9s
Precision: 64
Internal Precision: 128
\[\sqrt[3]{x + 1} - \sqrt[3]{x}\]
↓
\[\frac{1}{\left(\sqrt[3]{x} \cdot \sqrt[3]{x} + \left(\sqrt{\sqrt[3]{x}} \cdot \sqrt{\sqrt[3]{x}}\right) \cdot \sqrt[3]{x + 1}\right) + \sqrt[3]{x + 1} \cdot \sqrt[3]{x + 1}}\]

Error

Bits error versus x

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Derivation

  1. Initial program 29.6

    \[\sqrt[3]{x + 1} - \sqrt[3]{x}\]
  2. Using strategy rm

  3. Applied flip3--29.6

    \[\leadsto \color{blue}{\frac{{\left(\sqrt[3]{x + 1}\right)}^{3} - {\left(\sqrt[3]{x}\right)}^{3}}{\sqrt[3]{x + 1} \cdot \sqrt[3]{x + 1} + \left(\sqrt[3]{x} \cdot \sqrt[3]{x} + \sqrt[3]{x + 1} \cdot \sqrt[3]{x}\right)}}\]

  4. Taylor expanded around inf 0.6

    \[\leadsto \frac{\color{blue}{1}}{\sqrt[3]{x + 1} \cdot \sqrt[3]{x + 1} + \left(\sqrt[3]{x} \cdot \sqrt[3]{x} + \sqrt[3]{x + 1} \cdot \sqrt[3]{x}\right)}\]
  5. Using strategy rm

  6. Applied add-sqr-sqrt0.6

    \[\leadsto \frac{1}{\sqrt[3]{x + 1} \cdot \sqrt[3]{x + 1} + \left(\sqrt[3]{x} \cdot \sqrt[3]{x} + \sqrt[3]{x + 1} \cdot \color{blue}{\left(\sqrt{\sqrt[3]{x}} \cdot \sqrt{\sqrt[3]{x}}\right)}\right)}\]

  7. Final simplification0.6

    \[\leadsto \frac{1}{\left(\sqrt[3]{x} \cdot \sqrt[3]{x} + \left(\sqrt{\sqrt[3]{x}} \cdot \sqrt{\sqrt[3]{x}}\right) \cdot \sqrt[3]{x + 1}\right) + \sqrt[3]{x + 1} \cdot \sqrt[3]{x + 1}}\]

Reproduce

herbie shell --seed 2019016 
(FPCore (x)
  :name "2cbrt (problem 3.3.4)"
  (- (cbrt (+ x 1)) (cbrt x)))

Details

Time bar (total: 11.2s)Debug log

sample94.0ms

Algorithm
intervals
Results
573×(pre true 80)
316×(body nan 80)
138×(body real 80)
60×(body real 1280)
39×(body real 640)
11×(body real 320)
9×(body real 160)

simplify7.0ms

Counts
1 → 1
Calls
1 calls:
Slowest
7.0ms
(- (cbrt (+ x 1)) (cbrt x))

prune9.0ms

Pruning

1 alts after pruning (1 fresh and 0 done)

Merged error: 28.5b

localize21.0ms

Local error

Found 3 expressions with local error:

2.4b
(- (cbrt (+ x 1)) (cbrt x))
0.6b
(cbrt x)
0.3b
(cbrt (+ x 1))

rewrite12.0ms

Algorithm
rewrite-expression-head
Rules
8×add-sqr-sqrt
6×*-un-lft-identity
5×add-log-exp
4×add-cube-cbrt
4×cbrt-prod
3×add-exp-log
3×add-cbrt-cube
3×pow1
2×difference-of-squares
2×pow1/3
2×cbrt-div
1×distribute-lft-out--
1×flip--
1×flip-+
1×diff-log
1×flip3--
1×flip3-+
1×sub-neg
Counts
3 → 36
Calls
3 calls:
Slowest
10.0ms
(- (cbrt (+ x 1)) (cbrt x))
1.0ms
(cbrt (+ x 1))
0.0ms
(cbrt x)

series403.0ms

Counts
3 → 9
Calls
3 calls:
Slowest
245.0ms
(cbrt x)
109.0ms
(- (cbrt (+ x 1)) (cbrt x))
49.0ms
(cbrt (+ x 1))

simplify911.0ms

Counts
20 → 45
Calls
20 calls:
Slowest
220.0ms
(- (+ (exp (* 1/3 (- (log -1) (log (/ -1 x))))) (* 1/3 (/ (exp (* 1/3 (- (log -1) (log (/ -1 x))))) x))) (+ (* (pow (* x -1) 1/3) (cbrt -1)) (* 1/9 (/ (exp (* 1/3 (- (log -1) (log (/ -1 x))))) (pow x 2)))))
216.0ms
(- (+ (* 1/3 x) 1) (+ (* 1/9 (pow x 2)) (pow x 1/3)))
181.0ms
(- (+ (exp (* 1/3 (- (log -1) (log (/ -1 x))))) (* 1/3 (/ (exp (* 1/3 (- (log -1) (log (/ -1 x))))) x))) (* 1/9 (/ (exp (* 1/3 (- (log -1) (log (/ -1 x))))) (pow x 2))))
82.0ms
(- (+ (* 1/3 (pow (/ 1 (pow x 2)) 1/3)) (* 5/81 (pow (/ 1 (pow x 8)) 1/3))) (* 1/9 (pow (/ 1 (pow x 5)) 1/3)))
67.0ms
(- (+ (* 1/3 (pow (/ 1 (pow x 2)) 1/3)) (pow (/ 1 x) -1/3)) (* 1/9 (pow (/ 1 (pow x 5)) 1/3)))

prune442.0ms

Pruning

7 alts after pruning (7 fresh and 0 done)

Merged error: 16.4b

localize37.0ms

Local error

Found 4 expressions with local error:

1.7b
(- (pow (cbrt (+ x 1)) 3) (pow (cbrt x) 3))
0.7b
(pow (cbrt x) 3)
0.6b
(cbrt x)
0.6b
(cbrt x)

rewrite18.0ms

Algorithm
rewrite-expression-head
Rules
36×add-sqr-sqrt
18×cube-prod
18×unpow-prod-down
16×*-un-lft-identity
15×difference-of-squares
6×add-log-exp
6×add-cube-cbrt
6×cbrt-prod
5×distribute-lft-out--
5×add-exp-log
5×pow1
4×add-cbrt-cube
3×pow1/3
2×pow-pow
1×rem-cube-cbrt
1×flip--
1×pow-exp
1×unpow3
1×diff-log
1×flip3--
1×sub-neg
1×difference-cubes
1×pow-to-exp
1×cube-mult
Counts
4 → 69
Calls
4 calls:
Slowest
16.0ms
(- (pow (cbrt (+ x 1)) 3) (pow (cbrt x) 3))
1.0ms
(pow (cbrt x) 3)
0.0ms
(cbrt x)
0.0ms
(cbrt x)

series934.0ms

Counts
4 → 12
Calls
4 calls:
Slowest
308.0ms
(pow (cbrt x) 3)
305.0ms
(cbrt x)
248.0ms
(cbrt x)
72.0ms
(- (pow (cbrt (+ x 1)) 3) (pow (cbrt x) 3))

simplify546.0ms

Counts
62 → 81
Calls
62 calls:
Slowest
31.0ms
(/ (exp (pow (cbrt (+ x 1)) 3)) (exp (pow (cbrt x) 3)))
25.0ms
(- (pow (cbrt (sqrt (+ x 1))) 3) (pow (sqrt (cbrt x)) 3))
25.0ms
(- (pow (cbrt (sqrt (+ x 1))) 3) (pow (sqrt (cbrt x)) 3))
25.0ms
(- (sqrt (pow (cbrt (+ x 1)) 3)) (pow (sqrt (cbrt x)) 3))
20.0ms
(- (pow (sqrt (cbrt (+ x 1))) 3) (sqrt (pow (cbrt x) 3)))

prune854.0ms

Pruning

5 alts after pruning (5 fresh and 0 done)

Merged error: 0.4b

localize5.0ms

Local error

Found 4 expressions with local error:

0.6b
(cbrt x)
0.6b
(cbrt x)
0.6b
(cbrt x)
0.5b
(* (cbrt x) (cbrt x))

rewrite4.0ms

Algorithm
rewrite-expression-head
Rules
9×pow1
7×pow1/3
6×add-cube-cbrt
6×add-exp-log
6×*-un-lft-identity
6×add-sqr-sqrt
4×add-log-exp
4×add-cbrt-cube
3×associate-*l*
3×associate-*r*
2×pow-prod-up
2×pow-prod-down
1×cbrt-unprod
1×*-commutative
1×prod-exp
1×pow-plus
1×pow2
Counts
4 → 46
Calls
4 calls:
Slowest
3.0ms
(* (cbrt x) (cbrt x))
0.0ms
(cbrt x)
0.0ms
(cbrt x)
0.0ms
(cbrt x)

series1.2s

Counts
4 → 12
Calls
4 calls:
Slowest
339.0ms
(* (cbrt x) (cbrt x))
312.0ms
(cbrt x)
312.0ms
(cbrt x)
212.0ms
(cbrt x)

simplify75.0ms

Counts
25 → 58
Calls
25 calls:
Slowest
16.0ms
(* (pow (pow x 2) 1/3) (pow (cbrt -1) 2))
8.0ms
(* (pow (* x -1) 1/3) (cbrt -1))
8.0ms
(* (pow (* x -1) 1/3) (cbrt -1))
8.0ms
(* (pow (* x -1) 1/3) (cbrt -1))
3.0ms
(pow (/ 1 x) -1/3)

prune769.0ms

Pruning

16 alts after pruning (15 fresh and 1 done)

Merged error: 0.3b

localize20.0ms

Local error

Found 4 expressions with local error:

0.6b
(cbrt x)
0.6b
(cbrt x)
0.6b
(cbrt x)
0.6b
(cbrt x)

rewrite1.0ms

Algorithm
rewrite-expression-head
Rules
4×add-log-exp
4×add-cube-cbrt
4×add-exp-log
4×pow1/3
4×add-cbrt-cube
4×*-un-lft-identity
4×pow1
4×add-sqr-sqrt
Counts
4 → 32
Calls
4 calls:
Slowest
0.0ms
(cbrt x)
0.0ms
(cbrt x)
0.0ms
(cbrt x)
0.0ms
(cbrt x)

series1.2s

Counts
4 → 12
Calls
4 calls:
Slowest
329.0ms
(cbrt x)
324.0ms
(cbrt x)
303.0ms
(cbrt x)
277.0ms
(cbrt x)

simplify33.0ms

Counts
12 → 44
Calls
12 calls:
Slowest
7.0ms
(* (pow (* x -1) 1/3) (cbrt -1))
5.0ms
(* (pow (* x -1) 1/3) (cbrt -1))
5.0ms
(* (pow (* x -1) 1/3) (cbrt -1))
5.0ms
(* (pow (* x -1) 1/3) (cbrt -1))
2.0ms
(pow (/ 1 x) -1/3)

prune488.0ms

Pruning

17 alts after pruning (15 fresh and 2 done)

Merged error: 0.2b

regimes259.0ms

Accuracy

0% (0.3b remaining)

Error of 0.6b against oracle of 0.3b and baseline of 0.6b

bsearch3.0ms

end0.0ms

sample2.9s

Algorithm
intervals
Results
16094×(pre true 80)
8093×(body nan 80)
4124×(body real 80)
1740×(body real 1280)
1213×(body real 640)
610×(body real 320)
314×(body real 160)