How to avoid 'Index in position 1 is invalid.'

If I ask matlab to give me for example A(i - 1, j - 1) and A(i, j + 1) if matrix A and indices i, j are given, and one of them doesn't exist(because 'Index in position 1 is invalid'), how do I ignore the element that doesn't exist but print the other element(s)? For example, is there a function to test if those elements exist? Thanks!

[madhan ravi]

example?

Answer 1

[Image Analyst]

Well you could let it throw an error. Or you could detect it in advance and throw a "friendlier" error

[rows, columns] = size(A);
row = i - 1; % Whatever....
col = j + 1;
if row < 1 || row > rows
    warningMessage = sprintf('Error for i=%d, i-1 would give a row outside the range [1, %d], i, rows);
    uiwait(errordlg(warningMessage));
end
if col< 1 || col > columns
    warningMessage = sprintf('Error for j=%d, this would give a column outside the range [1, %d], j, columns);
    uiwait(errordlg(warningMessage));
end

Or something similar. Or you could clip the values to the valid range.

row = max(1, i-1);
row = min(row, rows);
col = max(1, j-1);
col = min(col, columns);