automatically filling a matrix

Hi community,

n=200;

i=3;

j=6;

I want to create a matrix which fills a matrix of (n*j) x j and has in the first column -1 for the first n numbers and the rest zeros and for the second column n zeros,n -ones and for the rest zeros again.

I created one manually for the following situation of n=200;i=3;j=6; However, I want to create a script in which I can increase the values of n,i,j and Matlab automatically generates a new correct matrix. Does anyone know how to do this?

My own code is

% when n=200; i=3; and j=6; 
AX1= [-ones(n,1);zeros(5*n,1)];
AX2= [zeros(n,1);-ones(n,1);zeros(4*n,1)];
AX3= [zeros(2*n,1);-ones(n,1);zeros(3*n,1)];
AX4= [zeros(3*n,1);-ones(n,1);zeros(2*n,1)];
AX5= [zeros(4*n,1);-ones(n,1);zeros(n,1)];
AX6= [zeros(5*n,1);-ones(n,1)];

AX=[AX1,AX2,AX3,AX4,AX5,AX6];

Thanks in advance!

Answer 1

[Stephen23]

Method one: eye and kron:

>> n = 5;
>> j = 6;
>> M = kron(-eye(j),ones(n,1))
M =
    -1     0     0     0     0     0
    -1     0     0     0     0     0
    -1     0     0     0     0     0
    -1     0     0     0     0     0
    -1     0     0     0     0     0
     0    -1     0     0     0     0
     0    -1     0     0     0     0
     0    -1     0     0     0     0
     0    -1     0     0     0     0
     0    -1     0     0     0     0
     0     0    -1     0     0     0
     0     0    -1     0     0     0
     0     0    -1     0     0     0
     0     0    -1     0     0     0
     0     0    -1     0     0     0
     0     0     0    -1     0     0
     0     0     0    -1     0     0
     0     0     0    -1     0     0
     0     0     0    -1     0     0
     0     0     0    -1     0     0
     0     0     0     0    -1     0
     0     0     0     0    -1     0
     0     0     0     0    -1     0
     0     0     0     0    -1     0
     0     0     0     0    -1     0
     0     0     0     0     0    -1
     0     0     0     0     0    -1
     0     0     0     0     0    -1
     0     0     0     0     0    -1
     0     0     0     0     0    -1

Method two: eye and repelem:

>> M = repelem(-eye(j),n,1)
M =
    -1     0     0     0     0     0
    -1     0     0     0     0     0
    -1     0     0     0     0     0
    -1     0     0     0     0     0
    -1     0     0     0     0     0
     0    -1     0     0     0     0
     0    -1     0     0     0     0
     0    -1     0     0     0     0
     0    -1     0     0     0     0
     0    -1     0     0     0     0
     0     0    -1     0     0     0
     0     0    -1     0     0     0
     0     0    -1     0     0     0
     0     0    -1     0     0     0
     0     0    -1     0     0     0
     0     0     0    -1     0     0
     0     0     0    -1     0     0
     0     0     0    -1     0     0
     0     0     0    -1     0     0
     0     0     0    -1     0     0
     0     0     0     0    -1     0
     0     0     0     0    -1     0
     0     0     0     0    -1     0
     0     0     0     0    -1     0
     0     0     0     0    -1     0
     0     0     0     0     0    -1
     0     0     0     0     0    -1
     0     0     0     0     0    -1
     0     0     0     0     0    -1
     0     0     0     0     0    -1

Method three: blkdiag and a comma separated list:

>> C = {-ones(n,1)};
>> M = blkdiag(C{ones(1,j)})
M =
    -1     0     0     0     0     0
    -1     0     0     0     0     0
    -1     0     0     0     0     0
    -1     0     0     0     0     0
    -1     0     0     0     0     0
     0    -1     0     0     0     0
     0    -1     0     0     0     0
     0    -1     0     0     0     0
     0    -1     0     0     0     0
     0    -1     0     0     0     0
     0     0    -1     0     0     0
     0     0    -1     0     0     0
     0     0    -1     0     0     0
     0     0    -1     0     0     0
     0     0    -1     0     0     0
     0     0     0    -1     0     0
     0     0     0    -1     0     0
     0     0     0    -1     0     0
     0     0     0    -1     0     0
     0     0     0    -1     0     0
     0     0     0     0    -1     0
     0     0     0     0    -1     0
     0     0     0     0    -1     0
     0     0     0     0    -1     0
     0     0     0     0    -1     0
     0     0     0     0     0    -1
     0     0     0     0     0    -1
     0     0     0     0     0    -1
     0     0     0     0     0    -1
     0     0     0     0     0    -1

See also: https://www.mathworks.com/matlabcentral/answers/320713-how-to-operate-on-comma-separated-lists

[bus14]

Great thanks for your help