Average Error: 42.0 → 10.6
Time: 34.2s
Precision: 64
Internal Precision: 128
\[100 \cdot \frac{{\left(1 + \frac{i}{n}\right)}^{n} - 1}{\frac{i}{n}}\]
\[\begin{array}{l} \mathbf{if}\;i \le -9.786895623065357 \cdot 10^{-113}:\\ \;\;\;\;\frac{1}{\frac{\frac{i}{n}}{(e^{\log_* (1 + \frac{i}{n}) \cdot n} - 1)^* \cdot 100}}\\ \mathbf{elif}\;i \le 9.869555751605711 \cdot 10^{-90} \lor \neg \left(i \le 7.239073862837944 \cdot 10^{+78}\right):\\ \;\;\;\;\frac{1}{(\left(\frac{\frac{1}{200}}{n}\right) \cdot \left(\frac{i}{n} - i\right) + \left(\frac{\frac{1}{100}}{n}\right))_*}\\ \mathbf{else}:\\ \;\;\;\;n \cdot \left(100 \cdot \frac{(e^{\log_* (1 + \frac{i}{n}) \cdot n} - 1)^*}{i}\right)\\ \end{array}\]

Error

Bits error versus i

Bits error versus n

Target

Original42.0
Target41.5
Herbie10.6
\[100 \cdot \frac{e^{n \cdot \begin{array}{l} \mathbf{if}\;1 + \frac{i}{n} = 1:\\ \;\;\;\;\frac{i}{n}\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{i}{n} \cdot \log \left(1 + \frac{i}{n}\right)}{\left(\frac{i}{n} + 1\right) - 1}\\ \end{array}} - 1}{\frac{i}{n}}\]

Derivation

  1. Split input into 3 regimes
  2. if i < -9.786895623065357e-113

    1. Initial program 35.6

      \[100 \cdot \frac{{\left(1 + \frac{i}{n}\right)}^{n} - 1}{\frac{i}{n}}\]
    2. Using strategy rm
    3. Applied pow-to-exp35.6

      \[\leadsto 100 \cdot \frac{\color{blue}{e^{\log \left(1 + \frac{i}{n}\right) \cdot n}} - 1}{\frac{i}{n}}\]
    4. Applied expm1-def29.6

      \[\leadsto 100 \cdot \frac{\color{blue}{(e^{\log \left(1 + \frac{i}{n}\right) \cdot n} - 1)^*}}{\frac{i}{n}}\]
    5. Simplified2.6

      \[\leadsto 100 \cdot \frac{(e^{\color{blue}{n \cdot \log_* (1 + \frac{i}{n})}} - 1)^*}{\frac{i}{n}}\]
    6. Using strategy rm
    7. Applied associate-*r/2.5

      \[\leadsto \color{blue}{\frac{100 \cdot (e^{n \cdot \log_* (1 + \frac{i}{n})} - 1)^*}{\frac{i}{n}}}\]
    8. Using strategy rm
    9. Applied clear-num2.8

      \[\leadsto \color{blue}{\frac{1}{\frac{\frac{i}{n}}{100 \cdot (e^{n \cdot \log_* (1 + \frac{i}{n})} - 1)^*}}}\]

    if -9.786895623065357e-113 < i < 9.869555751605711e-90 or 7.239073862837944e+78 < i

    1. Initial program 44.9

      \[100 \cdot \frac{{\left(1 + \frac{i}{n}\right)}^{n} - 1}{\frac{i}{n}}\]
    2. Using strategy rm
    3. Applied pow-to-exp49.5

      \[\leadsto 100 \cdot \frac{\color{blue}{e^{\log \left(1 + \frac{i}{n}\right) \cdot n}} - 1}{\frac{i}{n}}\]
    4. Applied expm1-def45.3

      \[\leadsto 100 \cdot \frac{\color{blue}{(e^{\log \left(1 + \frac{i}{n}\right) \cdot n} - 1)^*}}{\frac{i}{n}}\]
    5. Simplified34.0

      \[\leadsto 100 \cdot \frac{(e^{\color{blue}{n \cdot \log_* (1 + \frac{i}{n})}} - 1)^*}{\frac{i}{n}}\]
    6. Using strategy rm
    7. Applied associate-*r/34.0

      \[\leadsto \color{blue}{\frac{100 \cdot (e^{n \cdot \log_* (1 + \frac{i}{n})} - 1)^*}{\frac{i}{n}}}\]
    8. Using strategy rm
    9. Applied clear-num34.2

      \[\leadsto \color{blue}{\frac{1}{\frac{\frac{i}{n}}{100 \cdot (e^{n \cdot \log_* (1 + \frac{i}{n})} - 1)^*}}}\]
    10. Taylor expanded around 0 21.6

      \[\leadsto \frac{1}{\color{blue}{\left(\frac{1}{200} \cdot \frac{i}{{n}^{2}} + \frac{1}{100} \cdot \frac{1}{n}\right) - \frac{1}{200} \cdot \frac{i}{n}}}\]
    11. Simplified15.9

      \[\leadsto \frac{1}{\color{blue}{(\left(\frac{\frac{1}{200}}{n}\right) \cdot \left(\frac{i}{n} - i\right) + \left(\frac{\frac{1}{100}}{n}\right))_*}}\]

    if 9.869555751605711e-90 < i < 7.239073862837944e+78

    1. Initial program 46.4

      \[100 \cdot \frac{{\left(1 + \frac{i}{n}\right)}^{n} - 1}{\frac{i}{n}}\]
    2. Using strategy rm
    3. Applied pow-to-exp47.4

      \[\leadsto 100 \cdot \frac{\color{blue}{e^{\log \left(1 + \frac{i}{n}\right) \cdot n}} - 1}{\frac{i}{n}}\]
    4. Applied expm1-def35.8

      \[\leadsto 100 \cdot \frac{\color{blue}{(e^{\log \left(1 + \frac{i}{n}\right) \cdot n} - 1)^*}}{\frac{i}{n}}\]
    5. Simplified6.4

      \[\leadsto 100 \cdot \frac{(e^{\color{blue}{n \cdot \log_* (1 + \frac{i}{n})}} - 1)^*}{\frac{i}{n}}\]
    6. Using strategy rm
    7. Applied associate-/r/7.0

      \[\leadsto 100 \cdot \color{blue}{\left(\frac{(e^{n \cdot \log_* (1 + \frac{i}{n})} - 1)^*}{i} \cdot n\right)}\]
    8. Applied associate-*r*6.9

      \[\leadsto \color{blue}{\left(100 \cdot \frac{(e^{n \cdot \log_* (1 + \frac{i}{n})} - 1)^*}{i}\right) \cdot n}\]
  3. Recombined 3 regimes into one program.
  4. Final simplification10.6

    \[\leadsto \begin{array}{l} \mathbf{if}\;i \le -9.786895623065357 \cdot 10^{-113}:\\ \;\;\;\;\frac{1}{\frac{\frac{i}{n}}{(e^{\log_* (1 + \frac{i}{n}) \cdot n} - 1)^* \cdot 100}}\\ \mathbf{elif}\;i \le 9.869555751605711 \cdot 10^{-90} \lor \neg \left(i \le 7.239073862837944 \cdot 10^{+78}\right):\\ \;\;\;\;\frac{1}{(\left(\frac{\frac{1}{200}}{n}\right) \cdot \left(\frac{i}{n} - i\right) + \left(\frac{\frac{1}{100}}{n}\right))_*}\\ \mathbf{else}:\\ \;\;\;\;n \cdot \left(100 \cdot \frac{(e^{\log_* (1 + \frac{i}{n}) \cdot n} - 1)^*}{i}\right)\\ \end{array}\]

Reproduce

herbie shell --seed 2018365 +o rules:numerics
(FPCore (i n)
  :name "Compound Interest"

  :herbie-target
  (* 100 (/ (- (exp (* n (if (== (+ 1 (/ i n)) 1) (/ i n) (/ (* (/ i n) (log (+ 1 (/ i n)))) (- (+ (/ i n) 1) 1))))) 1) (/ i n)))

  (* 100 (/ (- (pow (+ 1 (/ i n)) n) 1) (/ i n))))

Details

Time bar (total: 17.7s)Debug log

start467.0ms

Algorithm
intervals

setup355.0ms

Pruning

2 alts after pruning (2 fresh and 0 done)

Merged error: 42.0b

localize34.0ms

Local error

Found 4 expressions with local error:

10.7b
(/ (- (pow (+ 1 (/ i n)) n) 1) (/ i n))
7.8b
(pow (+ 1 (/ i n)) n)
1.6b
(- (pow (+ 1 (/ i n)) n) 1)
0.1b
(* 100 (/ (- (pow (+ 1 (/ i n)) n) 1) (/ i n)))

rewrite44.0ms

Algorithm
rewrite-expression-head
Counts
4 → 122
Calls

4 calls. Slowest were:

19.0ms
(/ (- (pow (+ 1 (/ i n)) n) 1) (/ i n))
13.0ms
(- (pow (+ 1 (/ i n)) n) 1)
9.0ms
(* 100 (/ (- (pow (+ 1 (/ i n)) n) 1) (/ i n)))

series893.0ms

Counts
4 → 12
Calls

4 calls. Slowest were:

288.0ms
(/ (- (pow (+ 1 (/ i n)) n) 1) (/ i n))
276.0ms
(* 100 (/ (- (pow (+ 1 (/ i n)) n) 1) (/ i n)))
184.0ms
(- (pow (+ 1 (/ i n)) n) 1)
145.0ms
(pow (+ 1 (/ i n)) n)

simplify4.4s

Counts
105 → 134
Calls

105 calls. Slowest were:

360.0ms
(/ (* (- (exp (* (- (log (/ 1 n)) (log (/ 1 i))) n)) 1) n) i)
346.0ms
(/ (* (* (- (pow (+ 1 (/ i n)) n) 1) (- (pow (+ 1 (/ i n)) n) 1)) (- (pow (+ 1 (/ i n)) n) 1)) (* (* (/ i n) (/ i n)) (/ i n)))
281.0ms
(- (exp (* (- (log (/ 1 n)) (log (/ 1 i))) n)) 1)

prune1.5s

Pruning

6 alts after pruning (6 fresh and 0 done)

Merged error: 10.4b

localize23.0ms

Local error

Found 4 expressions with local error:

10.6b
(/ (expm1 (* n (log1p (/ i n)))) (/ i n))
10.5b
(* n (log1p (/ i n)))
7.0b
(log1p (/ i n))
0.2b
(* 100 (/ (expm1 (* n (log1p (/ i n)))) (/ i n)))

rewrite15.0ms

Algorithm
rewrite-expression-head
Counts
4 → 87
Calls

4 calls. Slowest were:

7.0ms
(/ (expm1 (* n (log1p (/ i n)))) (/ i n))
3.0ms
(* 100 (/ (expm1 (* n (log1p (/ i n)))) (/ i n)))
2.0ms
(* n (log1p (/ i n)))

series715.0ms

Counts
4 → 12
Calls

4 calls. Slowest were:

305.0ms
(/ (expm1 (* n (log1p (/ i n)))) (/ i n))
290.0ms
(* 100 (/ (expm1 (* n (log1p (/ i n)))) (/ i n)))
64.0ms
(* n (log1p (/ i n)))
56.0ms
(log1p (/ i n))

simplify1.1s

Counts
66 → 99
Calls

66 calls. Slowest were:

198.0ms
(/ (* (* (expm1 (* n (log1p (/ i n)))) (expm1 (* n (log1p (/ i n))))) (expm1 (* n (log1p (/ i n))))) (* (* (/ i n) (/ i n)) (/ i n)))
83.0ms
(- (log (/ -1 n)) (log (/ -1 i)))
83.0ms
(/ (* (- (* 100 (exp i)) 100) n) i)

prune1.1s

Pruning

9 alts after pruning (9 fresh and 0 done)

Merged error: 10.2b

localize14.0ms

Local error

Found 4 expressions with local error:

10.7b
(/ (* 100 (expm1 (* n (log1p (/ i n))))) (/ i n))
10.5b
(* n (log1p (/ i n)))
7.0b
(log1p (/ i n))
0.1b
(* 100 (expm1 (* n (log1p (/ i n)))))

rewrite14.0ms

Algorithm
rewrite-expression-head
Counts
4 → 61
Calls

4 calls. Slowest were:

8.0ms
(/ (* 100 (expm1 (* n (log1p (/ i n))))) (/ i n))
2.0ms
(* 100 (expm1 (* n (log1p (/ i n)))))
2.0ms
(* n (log1p (/ i n)))

series619.0ms

Counts
4 → 12
Calls

4 calls. Slowest were:

317.0ms
(/ (* 100 (expm1 (* n (log1p (/ i n))))) (/ i n))
210.0ms
(* 100 (expm1 (* n (log1p (/ i n)))))
46.0ms
(* n (log1p (/ i n)))
46.0ms
(log1p (/ i n))

simplify647.0ms

Counts
33 → 73
Calls

33 calls. Slowest were:

118.0ms
(- (log (* 100 (expm1 (* n (log1p (/ i n)))))) (log (/ i n)))
105.0ms
(/ (* (* (* 100 (expm1 (* n (log1p (/ i n))))) (* 100 (expm1 (* n (log1p (/ i n)))))) (* 100 (expm1 (* n (log1p (/ i n)))))) (* (* (/ i n) (/ i n)) (/ i n)))
80.0ms
(- (log (/ -1 n)) (log (/ -1 i)))

prune955.0ms

Pruning

7 alts after pruning (7 fresh and 0 done)

Merged error: 10.2b

localize12.0ms

Local error

Found 4 expressions with local error:

10.6b
(/ (/ i n) (* 100 (expm1 (* n (log1p (/ i n))))))
10.5b
(* n (log1p (/ i n)))
7.0b
(log1p (/ i n))
0.7b
(/ 1 (/ (/ i n) (* 100 (expm1 (* n (log1p (/ i n)))))))

rewrite7.0ms

Algorithm
rewrite-expression-head
Counts
4 → 73
Calls

4 calls. Slowest were:

3.0ms
(/ (/ i n) (* 100 (expm1 (* n (log1p (/ i n))))))
2.0ms
(/ 1 (/ (/ i n) (* 100 (expm1 (* n (log1p (/ i n)))))))
1.0ms
(* n (log1p (/ i n)))

series859.0ms

Counts
4 → 12
Calls

4 calls. Slowest were:

530.0ms
(/ (/ i n) (* 100 (expm1 (* n (log1p (/ i n))))))
245.0ms
(/ 1 (/ (/ i n) (* 100 (expm1 (* n (log1p (/ i n)))))))
47.0ms
(log1p (/ i n))
37.0ms
(* n (log1p (/ i n)))

simplify1.7s

Counts
39 → 85
Calls

39 calls. Slowest were:

273.0ms
(* 1/100 (/ i (* n (- (exp (* n (- (log (/ -1 n)) (log (/ -1 i))))) 1))))
260.0ms
(* 100 (/ (* (- (exp (* (- (log (/ 1 n)) (log (/ 1 i))) n)) 1) n) i))
216.0ms
(* 100 (/ (* n (- (exp (* n (- (log (/ -1 n)) (log (/ -1 i))))) 1)) i))

prune956.0ms

Pruning

7 alts after pruning (6 fresh and 1 done)

Merged error: 0.2b

regimes225.0ms

Accuracy

48% (10.5b remaining)

Error of 10.6b against oracle of 0.1b and baseline of 20.2b

bsearch1.1s