How do i get the compressed sparse row for the following matrix ?

How can i get the compressed sparse row for the folling matrix ?

I am trying to solve a 14 bus Power Flow real life problem. testing a 5x5 matrix first to see if it will work.

So far i have the code given below.

A=[ 1 0 -2 0 0;...

2 8 0 1 0;...

0 0 3 0 -2;...

0 -3 2 0 0;...

1 2 0 0 -4]

n=length(A);

c=1;

for i=1:n

for j=1:n

if A(i,j) ~= 0;

row(c,1)=i;

col(c,1)=j;

val(c,1)=A(i,j);

index(c,1)= c;

cz=[index val];

c=c+1;

end

end

end

Answer 1

[Vidhi Agarwal]

Hi De Silva,

I understand you have a query regarding creating a CSR for a given matrix.

Compressed Sparse Row (CSR) is a way to store sparse matrices, where most elements are zero, using less memory. It uses three arrays:

Values Array: Holds all non-zero elements in order.

Column Indices Array: Has the column positions for each non-zero element.

Row Pointers Array: Shows where each row's data starts in the Values Array, with one extra element at the end as a marker.

Following is the approch to do the same.

A = [ 1  0 -2  0  0;...
      2  8  0  1  0;...
      0  0  3  0 -2;...
      0 -3  2  0  0;...
      1  2  0  0 -4];

% Initialize the arrays
values = [];
col_indices = [];
row_pointers = [1]; % The first row always starts at index 1
for i = 1:size(A,1)
    for j = 1:size(A,2)
        if A(i,j) ~= 0
            values(end+1) = A(i,j);
            col_indices(end+1) = j;
        end
    end
    row_pointers(end+1) = length(values) + 1;
end
row_pointers(end) = [];

And than you can display the Values array, Column indices array and Row Pointers array.