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 Author Comment/Response Alexander 08/18/05 04:27am Hello! Here is simple example of defining list: b = Table[Symbol["a" <> ToString[i] <> ToString[j]], {i, 2}, {j, 2}]; a11 = IdentityMatrix[2]; b[[1,1]][[1,1]] Output will be number 1. Then we type another command: b[[1,1]][[1,1]]=2 wich cause error message. If we type ?b the structure of b can be seen: Global`b b = {{a11, a12}, {a21, a22}} And I wonder, how to change elements of aij from b? It's interesing question about how mathematica think things and how evaluate them. So, the questions are: 1) Why code above produce error message? 2) What difference between b[[1,1]][[1,1]] and b[[1,1,1,1]] notation? Here is an example concerning the second question: This code doesn't produce error: a11 = IdentityMatrix[2]; b = Table[Symbol["a" <> ToString[ i] <> ToString[j]], {i, 2}, {j, 2}]; b[[1, 1, 1, 1]] = 3 but this does: a11 = IdentityMatrix[2]; b = Table[Symbol["a" <> ToString[ i] <> ToString[j]], {i, 2}, {j, 2}]; b[[1, 1]][[1, 1]] = 3 Why? Sorry for my obscure speech, and thanks for your answers! URL: ,

 Subject (listing for 'Nested Lists,Definition and Evaluation.') Author Date Posted Nested Lists,Definition and Evaluation. Alexander 08/18/05 04:27am Re: Nested Lists,Definition and Evaluation. yehuda ben-s... 08/24/05 2:02pm
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