bad index into Matrix

pagan — Thu, 05 Jan 2012 06:51:33 Z

That error message often means that the code has referenced a Matrix with indices which are names which do not evaluate to integer values. For example

restart:

u:=Matrix([[3]]):

u[i,i];
Error, bad index into Matrix

The problem is that `i` was not an integer value (within the valid bounds range of just 1 to 1).

This can happen in a few ways. You might have a line of code where you intended `i` to have a value, but it actually didn't.

One common scenario is that the code calls `sum` and the first argument to the `sum` call is a formula containing things like u[i,j] say. Since `sum` does not have special evaluation rules Maple will try and evaluate u[i,j] before `i` and/or `j` the indices of summation get assigned any numeric values. And then bang. If that is your situation then try replacing calls to `sum`, for summing finitely many terms, by calls to `add` instead.

Now here is the best bit: in the Maple Standard GUI that error message is a hyperlink. If you follow its URL in a web browser then you will get to an Online help page which gives pretty much the same explanation.

thanks

hopereza86 — Fri, 06 Jan 2012 14:54:12 Z

thank u so much , by using add for sum my problem was removed.

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bad index into Matrix

thanks