# 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], ...