Re: question

• To: mathgroup at smc.vnet.net
• Subject: [mg15612] Re: question
• From: Fabien Boniver <F.Boniver at ulg.ac.be>
• Date: Sat, 30 Jan 1999 04:28:18 -0500 (EST)
• References: <78pa6k\$cn1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Dear Alice,

You can put  the result in a working function pFunction (or any other
name, of course) like this :

pFunction[s_]:=(P[t]/. DSolve[{P'[t]==0.031P[t], P[0]==5.3},
P[t],t][[1,1]])/.t->s

You can then compute explicit values of pFunction, the solution of your
diff. eq., like pFunction[10] or  pFunction[t].

The idea is to use the substitution rule given by Solve and then replace
the symbol t by the argument of the function to be defined.

Hope this can help.
Fabien

-
Fabien BONIVER

Inst. of Math., University of Liege
**
Universite de Liege
Service de Geometrie et Theorie des Algorithmes Institut de
Mathematique, B37
Grande Traverse, 12
4000 Sart Tilman (Liege),  Belgium
**
Email : F.Boniver at ulg.ac.be
Phone : + 32 4 366 94 17

"Alice M. Dean" wrote:

> Hi, I was given this address by a colleague, who said you could quickly
> answer what I think is a very simple question.  After I evaluate the
> following in mathematica,
>
> DSolve[{P'[t]==0.031P[t], P[0]==5.3}, P[t],t]
>
> I get a result which is essentially: {{P[t] -> 5.3 E ^(0.031t)}}
>
> inside two sets of curly brackets.
>
> I would now like to compute P[10], P[100], etc.  Is there a reasonable
> way to do this?  Thanks, Alice Dean
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~
> Alice Dean
> Mathematics & Computer Science Department Skidmore College
> Saratoga Springs, NY 12866
>
> Phone: (518) 580-5286
> Fax: (518) 580-5936
> Skidmore College Information: (518) 580-5000   E-mail:
> ~~~~~~~~~~~~~~~~~~~~~~~~~

--
Fabien BONIVER

Inst. of Math., University of Liege
**
Universite de Liege
Service de Geometrie et Theorie des Algorithmes Institut de
Mathematique, B37
Grande Traverse, 12
4000 Sart Tilman (Liege),  Belgium
**
Email : F.Boniver at ulg.ac.be
Phone : + 32 4 366 94 17

```

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