# Datastructures

## A-matrix

The A-matrix is stored in the lp structure in element matA and is defined in structure MATrec. Only the non-zero elements of this matrix are stored. This is called a sparse matrix. In MATrec, the following elements are of importance in the matrix data:

- rows
- columns
- col_end
- row_mat
- row_end
- col_mat_colnr
- col_mat_rownr
- col_mat_value

Elements are stored per column, then per row. col_mat_value containts the values. So first a[1][1], then a[2][1], then a[3][1], ..., a[2][1], a[2][2], ...