Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.soft-sys.math.mathematica > #3063

Re: Seaching in Pi a sequence. Looking for a faster method

Show all headers | View raw

This corrects the Dispatch table from my earlier solution (it wasn't  
general enough).

It also uses Sow, Reap, and Scan rather than Position, Part, and  
Accumulate.

It's not as fast as the other solution, but it's interesting.

Quit

piesimo3[n_, m_, r_] :=
  Module[{d = Dispatch@Thread[DeleteCases[Range[0, 9], m] -> -1],
    count = 1},
   First@Last@
     Reap@Scan[(Length@# == r && First@# == m && Sow@count;
         count += Length@#) &,
       Split[RealDigits[Pi - 3, 10, n][[1]] /. d]]
   ]
Timing@piesimo3[10^7, 9, 7]

{38.6643, {1722776, 3389380, 4313727, 5466169}}

Bobby

On Fri, 10 Jun 2011 05:38:05 -0500, Guillermo Sanchez  
<guillermo.sanchez@hotmail.com> wrote:

> Dear Group
>
> I have developed this function
>
> piesimo[n_, m_, r_] := Module[{a}, a = Split[RealDigits[Pi - 3, 10, n]
> [[1]]]; Part[Accumulate[Length /@ a], Flatten[Position[a, Table[m,
> {r}]]] - 1] + 1]
>
> n is the digits of Pi, after 3, where to search a sequence of m digit
> r times consecutives.
> For instance:
>
> piesimo[10^7, 9, 7]
>
> Gives that the sequence 9999999 happens in positions:
>
> {1722776, 3389380, 4313727, 5466169}
>
> I know that in this group I will find  faster methods. Any idea?
>
> Guillermo
>
>


-- 
DrMajorBob@yahoo.com

Back to comp.soft-sys.math.mathematica | Previous | Next | Find similar | Unroll thread

Thread

Re: Seaching in Pi a sequence. Looking for a faster method DrMajorBob <btreat1@austin.rr.com> - 2011-06-11 07:58 +0000

csiph-web