Weird!!!! Extremely simple question!! Can't assign values to first row of a sparse matrix, please help.

Hi, everyone

I got stuck by a very simple question. I simply can't believe that such a weird thing would happen here. I am using MATLAB 2016b.

I was trying to assign some values to a sparse matrix, but anyhow there is nothing in the first row of a sparse matrix, no matter what I give to the first row of the sparse matrix S.

Here is code:

S=sparse([],[],[],32,50,100);
s(1,21:30)=[1 1 1 1 7 5 1 1 1 1];
S(2,21:30)=[1 1 1 1 1 1 1 1 1 1];
S(3,21:30)=[1:10];
S(4,21:30)=[1 1 2 2 3 3 4 4 5 5];

The first row of matrix S is always empty. How come? What did I wrong?

Please help me out.

Thank you very much.

Answer 1

[James Tursa]

Typo. You used a small case 's' in that first row assignment. Change that to an upper case 'S' and everything will be as expected. MATLAB is a case sensitive language.

Answer 2

[Albert]

Thank you, James.

I know MATLAB is case sensitive, but I didn't realize that I used low case of the second 'S' in my code.

It's so good to stay in MATLAB community.

Thank you.