MATLAB: Extracting matrix diagonal with diag(A)

diag

A simple function that used to run now gives an error message. What am I doing wrong?
>> a = eye(4,4);
>> diag(a)
Subscript indices must either be real positive integers or logicals.
>>

Best Answer

Does this fix your problem?
a = eye(4,4) == 1;
diag(a)
While the diag function works fine, if you have a variable named diag (not a good idea--give it a unique name that isn't the same as a builtin function), it expects a logical, not double, input for indexing.
Related Question