define a sequence



There is some Maxima code for finding explicit formulae for  recursively 
defined sequences. 
Unfortunately, the code is so bug-ridden, I hesitate to encourage anyone 
to try it.  See 
the bug report at 

http://sourceforge.net/tracker/index.php?func=detail&aid=844521&group_id=4933&atid=104933

For your problem, Maxima is gets a correct value

(%i4) load("differ.mac")$

(%i6) difference(u[n]=2*u[n-1], u[n]);
difference:  no u[n+1] term -- u[n] = 2*u[n-1] 
(%o6) DONE

Okay, this doesn't seem to be the correct form for the input.....try 
again.

(%i7)  difference(u[n+1]=2*u[n], u[n]);
(%o7) u[n] = u[0]*2^n

Barton





Eric Delevaux <ericd@telefonica.net>
Sent by: maxima-admin@math.utexas.edu
09/07/2004 02:46 PM

 
        To:     maxima@math.utexas.edu
        cc: 
        Subject:        Re: [Maxima] define a sequence


Now i got my sequence u[n]=2*u[n-1]+1, no problem for the limit,
I tried 
makelist(u[n],n,1,9);
to obtain u_1 to u_9. It does work. Is there another way? With map?
Is there a way to obtain the expression of u[n] in function of n with an 
defintion by recurrance?
example : 
u_0=3
u_n=2*u_{n-1}

<verynycemaxymafunctioninordertoobtain:>

u_n=3*2^n
Bye
Eric

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