Advanced features

Simplex tableau data

HiGHS has a suite of methods for operations with the invertible representation of the current basis matrix $B$. To use these requires knowledge of the corresponding (ordered) basic variables. This is obtained using the method getBasicVariables , with non-negative values being columns and negative values corresponding to row indices plus one [so -1 indicates row 0]. Methods getBasisInverseRow and getBasisInverseCol yield a specific row or column of $B^{-1}$. Methods getBasisSolve and getBasisTransposeSolve yield the solution of $Bx=b$ and $Bx=b$ respectively. Finally, the methods getReducedRow and getReducedColumn yield a specific row or column of $B^{-1}A$. In all cases, HiGHS can return the number and indices of the nonzeros in the result.