If Qrows (first argument) is a sparse matrix (from 'Matrix' package), then the following arguments ('Qcols', 'Qvals', 'nrow' and 'ncol') are useless.

Three arrays (same dimension) which provide respectively the row, the column indices, as well as the value for the corresponding cell element.

If the argument 'nrow' and 'ncol' are not provided, they are calculated automatically from the contents of the sparse matrix.

Vector of initial values. It must have the same dimension as the rank of the sparse matrix defined above.

Right-hand side vector. It must have the same dimension as the rank of the sparse matrix defined above.

Verbose flag