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Re: treatment on C[i]

  • To: mathgroup at smc.vnet.net
  • Subject: [mg100321] Re: treatment on C[i]
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Mon, 1 Jun 2009 07:06:21 -0400 (EDT)
  • References: <gvtmfq$get$1@smc.vnet.net>

Hi,

it is a question of mathematics, how many free constants
you have.
For example:
DSolve[x''[t] + x[t] == 0, x[t], t]
has two free constants, because it is a
differential equation of second order and no initial
conditions are given. So, look onto your problem
and you will know how many free constants you have.

And

sol = DSolve[x''[t] + x[t] == 0, x[t], t];
Cases[sol, C[_], Infinity] // Union

work fine to extract the parameters

Regards
   Jens

olfa wrote:
> Hi mathematica community,
> C[i] is the default form for the i th parameter or constant generated
> by mathematica in representing the results of various symbolic
> computations in such functions as DSolve, RSolve and Reduce.
> My question is: is it possible to know in advance how many C[i]  will
> be generated?
>  If not how to represent the generic form of them: For example I have
> an input with reduce and mathematica generates in the output C[1],C
> [2],C[3] and C[4] so four C[i] in the solutions but before that when I
> wrote the input I did not know that it will generate four C[i] and I
> need to use something in the input that represent C[i] in general
> without knowing how many of them will be generated? I have tried to
> use the pattern object _  like that C[ _ ]  but it does not work.
> 
> Any suggestion?
> Thank you very much.
> 


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