Re: Did something change?

*To*: mathgroup at smc.vnet.net*Subject*: [mg58120] Re: [mg58109] Did something change?*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Sun, 19 Jun 2005 03:43:23 -0400 (EDT)*Reply-to*: hanlonr at cox.net*Sender*: owner-wri-mathgroup at wolfram.com

Do[F[i]=IdentityMatrix[8]; F[i]=ReplacePart[F[i], 7, {1,3}],{i,10}]; or Do[F[i]= ReplacePart[IdentityMatrix[8], 7, {1,3}], {i,10}]; Bob Hanlon > > From: Ronald Bruck <bruck at math.usc.edu> To: mathgroup at smc.vnet.net > Date: 2005/06/18 Sat AM 06:08:27 EDT > Subject: [mg58120] [mg58109] Did something change? > > Recently I created a list of several matrices, something like > > Do[F[i] = IdentityMatrix[8]; F[i][[1,3]] = 7, {i,10}] > > and was surprised to get the message that F[i] wasn't a symbol. I'm > pretty sure code similar to that worked prior to Mathematica 5. Did > something change? > > I've also tried Symbolize[F[i]] in that loop, but it doesn't help; > Mathematica refuses to access part [[1,3]] of F[i], claiming F[i] isn't > a symbol. > > How are you supposed to set the individual values of a matrix if you > can't do this? This is an EXTREMELY unhelpful "feature". > > --Ron Bruck > >