MATLAB: How to generate a matrix with number of lines inserted from keyboard

keyboard inputmatrix

I have to generate a matrix with i lines and j=i+1 collumns whose elements:
=2 if i=j;
=-1 if | i -j |=1;
=0 otherwise.
Here's my attempt at solving this problem:
prompt='Insert number of lines';
i=input(prompt)
j=i+1
% getting the number of lines and collumns
if i==j 
A=2*ones(i,j);
end
% checking the first condition for i and j
else if abs(i-j)==1
A=-1*ones(i,j);
end
%  checking the second condition for i and j
else
A=zeros(i,j)
% checking the third condition for i and j
end
end
A
% displaying matrix A
And I get this error when I try run it:
else if abs(i-j)==1
 |
Error: Illegal use of reserved keyword "else".
I don't understand what I'm doing wrong.

Best Answer

You had too many end statements. They were defining very short if blocks, and so some of those blocks did not begin correctly as a result.
Your code still has problems (it is not doing what you want it to). Since this appears to be a homework assignment, I will defer to you to get it running correctly.
This runs: 
if i==j
    A=2*ones(i,j);
    % checking the first condition for i and j
elseif abs(i-j)==1
    A=-1*ones(i,j);
    %  checking the second condition for i and j
else
    A=zeros(i,j)
    % checking the third condition for i and j
end
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