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Solve for positive, real-valued solutions


  • To: mathgroup@smc.vnet.net
  • Subject: [mg12415] Solve for positive, real-valued solutions
  • From: Walter Johnston <walterj@omega.uta.edu>
  • Date: Thu, 14 May 1998 11:15:25 -0400
  • Organization: University of Texas at Arlington

How can I tell Solve[] to give me only positive, real-valued solutions?

Long Version:

I am trying to build a table of values for use in a database. The
expression is 

P[c_,a_]:=(a^c/c!)/Sum[a^i/i!,{i,0,c}]. 

and I then tell the system to

Do[Print[cc," => ",Solve[P[c,a]==0.02,a]],{cc,51,100,1}]

which works, but gives me a lot more than I want. 

I have just started using Version 3.1 on my notebook (Windows NT 4.0)
and would really appreciate any suggestions on how to speed this up and
just get the positive, real-valued solutions I need for the database.

(RTFM statements won't help much. I am reading, but trying to shorten
the learning curve and get some solutions NOW.)

Thanks.

Walter Johnston




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