Re: O.D.E in Power Series

*To*: mathgroup at smc.vnet.net*Subject*: [mg18276] Re: O.D.E in Power Series*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Fri, 25 Jun 1999 15:05:22 -0400*Organization*: Universitaet Leipzig*References*: <7ku0dk$9a1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi Alan, if you want a general infinite power series you should try the SpecialFunction.m package from MathSource. If a solution to the first order terms is sufficient for you than deqn=y''[x]-2(x+3)y'[x]-3y[x]==0; order=10; Solve[LogicalExpand[ deqn /.Thread[ {#,D[#,x],D[#,{x,2}]} & /@ ( y[x]->Sum[a[i]*x^i,{i,0,order}]+O[x]^(order+1))]], Table[a[i],{i,2,order}]] will do it. Regards Jens ALAN S BLOOM wrote: > > I am trying to solve this equation below: > y''-2(x+3)y'-3y=0 with the DSolve command. > > DSolve [y''[x]-2(x+3)y'[x]-3y[x]==0,y[x],x] > > How can I make it work? > > Alan