Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2003
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2003

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

Search the Archive

Re: Processing lists of unrelated numbers with Do or While statement

  • To: mathgroup at smc.vnet.net
  • Subject: [mg39202] Re: Processing lists of unrelated numbers with Do or While statement
  • From: Bill Rowe <listuser at earthlink.net>
  • Date: Mon, 3 Feb 2003 01:10:28 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

On 2/2/03 at 1:13 AM, diana53xiii at earthlink.remove13.net (Diana) wrote:

>I had a problem recently where I tried to determing the PrimePi value
>of 2 times a number minus that number. This is verifying the
>Bertrand's Postulate:

>PrimePi(2x) - PrimePi(x) >=1 for all x >=2, elements of Z.

>I finally came up with: PrimePi[2*{2, 3, 5, 7, 13, 23, 43, 83, 163,
>317, 631, 1259, 2503, 4001} - {2, 3, 5, 7, 13, 23, 43, 83, 163, 317,
>631, 1259, 2503, 4001}]

>gives: {1, 2, 3, 4, 6, 9, 14, 23, 38, 66, 115, 205, 368, 551} the
>desired answer. 

Hmm... Your statement of your problem and the function agree but are not equivalent to
PrimePi[2x]-PrimePi[x].

Your function is PrimePi[2*list -list] = PrimePi[list] which is not equal to PrimePi[2*list]-PrimePi[list]

>Is there a way to process unrelated numbers with a Do
>or While or NestWhile statement? 

Clearly, the answer to your question is yes. A more specific answer depends on exactly what you mean by "process".

If process feed numbers to a function of n arguements m times then a better solution might be

MapThread[f, {list1, list2, .... listn}]


  • Prev by Date: RE: diffrence between ver 3.01 and 4.1 regarding N[]?
  • Next by Date: Re: RealOnly
  • Previous by thread: Processing lists of unrelated numbers with Do or While statement
  • Next by thread: Re: Processing lists of unrelated numbers with Do or While statement