MathGroup Archive 2000

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re:NestWhile


Dear mathgroup ,


Concerning my query before Easter,  about a version 3 equivalent to
NestWhile.

Thanks to Hartmut Wolf,  Daniel Reeves,  Andrzej Kozlowski,  and
Jens-Peer Kuska
for their solutions.

And I received an e-mail from Eric Bynum of Wolfram Technical Support,
with code
which  appropriately utilizes both Nest and While.  Thanks also, Eric.


Here is Eric's  Mathematica 3 Keith Sequence solution ;


In[1]:=
 V3KeithSequence[n_Integer?Positive] :=
    Module[{d = IntegerDigits[n], l, counter, lis},
      l = Length[d];
      counter = 1;
      While[Nest[Append[#, Plus @@ Take[#, -l]] &, d, counter][[-1]] <
n,
        counter++;
        lis = Nest[Append[#, Plus @@ Take[#, -l]] &, d, counter]];
      lis
      ]

 In[5]:=
  V3KeithSequence[197]

  Out[5]=
  {1, 9, 7, 17, 33, 57, 107, 197}


Where as before,  1+9+7=17,  9+7+17=33, etc., ending again with 197.




Alan Hopper

awhopper at hermes.net.au




  • Prev by Date: Re:SPlus-like Dataframe-IO/UpValue for lists
  • Next by Date: missing images
  • Previous by thread: Re: NestWhile
  • Next by thread: join/problem