Re: Recursion relation

*To*: mathgroup at yoda.physics.unc.edu*Subject*: Re: Recursion relation*From*: a_rubin at dsg4.dse.beckman.com (arthur rubin)*Date*: Fri, 10 Jul 92 07:43:25 PDT

You (martind at puhep1.princeton.edu) write: I'm trying to implement the following recursion relation for a certain index function c[i]: c[i] = r[i] - a[i,i-1]*c[i-1] where r[i] and a[i,i-1] are given functions. Namely, I'd like to have a function c[i+n_Integer] giving me the expression of c[i+n] in terms of r[i+n],r[i+n-1],...,r[i] and c[i-1]. DOES ANYBODY KNOW A WAY TO DO THIS ??? ------------------------------------------------------------------------------ c[X:i_Symbol + Optional[n_Integer]] := r[X] - a[X,X-1] c[X-1] /; n >= 0 or c[X] = cc[X+1] cc[X:_ + _Integer?Positive] := r[X-1] - a[X-1,X-2] cc[X-1] Format[cc[X_]] := HoldForm[c][X-1]