Re: Pattern Matching
- To: mathgroup at smc.vnet.net
- Subject: [mg23846] Re: Pattern Matching
- From: Brian Higgins <bghiggins at ucdavis.edu>
- Date: Mon, 12 Jun 2000 01:17:36 -0400 (EDT)
- References: <8hsu3g$dh4@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Johannes, Try the following pattern x[_]b[_] + __ -> z It seems to work on the expressions I tried: g=Sin[x]^2/(b[1]*x[1] + b[2]*x[2] + b[3]*x[3] + b[4]*x[4] + b[5]*x[5] + b[6]*x[6]) g/.x[_]b[_] + __ -> z Sin[x]^2/z Cheers, Brian In article <8hsu3g$dh4 at smc.vnet.net>, "Johannes Ludsteck" <ludsteck at zew.de> wrote: > Dear Group Members, > I would like to "find" and replace expressions with the simple > structure x[1] b[1]+x[2] b2]+...+x[n] b[n] > I tried to use the following replacement rule > In[27]:= x[1] b[1] + x[2] b[2] /. Plus[Times[x[_], b[_]] ..] -> z > > Out[27]= b[1] x[1] + b[2] x[2] + b[3] x[3] > Which didn't work (Out[27] should be z). > Why? > The following FullForm seems to give exactly the structure I used > in my replacement rule. > > In[17]:= > FullForm[x[1] b[1] + x[2] b[2] + x[3] b[3]] > Out[17]//FullForm= > Plus[Times[b[1], x[1]], Times[b[2], x[2]], Times[b[3], x[3]]] > > Even if this worked, my pattern wouldn't account for equal indices, > i.e. it would match x[1] b[500]+x[12] b[3], even if it shouldn't. > > Any suggestions? > Thanks, > Johannes Ludsteck > > Johannes Ludsteck > Centre for European Economic Research (ZEW) > Department of Labour Economics, > Human Resources and Social Policy > Phone (+49)(0)621/1235-157 > Fax (+49)(0)621/1235-225 > > P.O.Box 103443 > D-68034 Mannheim > GERMANY > > Email: ludsteck at zew.de > > Sent via Deja.com http://www.deja.com/ Before you buy.