MATLAB code error verification

Hi

What does the error shown below implies??

Index in position 2 exceeds array bounds (must not exceed 1)

Answer 1

[Jan]

This means, that in the failing line of code an index is applied to the 2nd dimension of a variable, which has the size 1 only in this dimension:

x = (1:3).'  % a column vector
x(1, 2)      % No, the length of the 2nd dimension is 1 only

Answer 2

[Steven Lord]

You're asking for an element of an array in a column that doesn't exist in that array. Consider a 4-by-4 matrix:

A = magic(4)

A = 4×4

16 2 3 13 5 11 10 8 9 7 6 12 4 14 15 1

What's the element in the third row and fifth column of A? Since A doesn't have a 5th column, this question doesn't make sense and so MATLAB throws an error.

y = A(3, 5)

Index in position 2 exceeds array bounds (must not exceed 4).

In particular, because the error says that the index in position 2 must not exceed 1 we know that the array into which you're trying to index only has 1 column but you're asking for an element in columns 2, 3, or 4, or an even later column number.