Re: setps problem/how to set matrix elements

*To*: mathgroup at smc.vnet.net*Subject*: [mg65854] Re: setps problem/how to set matrix elements*From*: bghiggins at ucdavis.edu*Date*: Wed, 19 Apr 2006 04:54:01 -0400 (EDT)*References*: <e1vet0$9db$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Rob, I would use ReplacePart to avoid the error FSD[r_, xdim_, ydim_] := Module[{}, ReplacePart[r, 5, {1, 1}]] To see what is going on try this simpler problem: b=(1,2) myfunc[b_]:=b[[1]]=5 Now evaluate Trace[myfunc[b]] Here is a snippet of the output {{b, {1, 2}}, myfunc[{1, 2}], {1, 2}[[1]] = 5, {Message[Set::setps, {1, 2}],.... During the evaluation b gets replaced with {1,2} so that Mathematica is trying to evaluate {1,2}[[1]] and hence the reason for the error. If on the other hand you evaluate c={1,2} Trace[c[[1]]=5] {c[[1]] = 5, 5} Hope this helps, Cheers, Brian