MathGroup Archive 2005

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

Search the Archive

Re: DSolve with recursively defined equations


DrBob solved my problem:

>The problem is that the expressions nn'[0, d] and nn'[i, d] don't make
any >sense. Try this instead:

>Clear[nn, eq, in, eqns, funcs];
>iCount = 2;
>eq[0] = D[nn[0, d], d] == -r nn[0, d];
>eq[i_] := D[nn[i, d], d] == r(nn[i - 1, d] - nn[i, d]);
>in[0] = nn[0, 0] == 1;
>in[i_] := nn[i, 0] == 0;
>eqns = Flatten[Table[{eq[i], in[i]}, {i, 0, iCount}]]
>funcs = Table[nn[i, d], {i, 0, iCount}]
>DSolve[eqns, funcs, d]

which works (Thank-you!). The second part of the problem is still
unresolved. I happen to know that the solution to the ith function is
nn[n_,d_] := Exp[-d r ] Sum[(r d)^i / i!, {i,0,n-1}]
How would I go about getting this general form in Mathematica?

Peter


  • Prev by Date: Re: Graphics'Master in 5.1
  • Next by Date: Re: FromDigits[{135,21}] -> 1371 (??!!)
  • Previous by thread: Re: DSolve with recursively defined equations
  • Next by thread: Re: DSolve with recursively defined equations