The function basis(C) computes a list of variables, one per equation, which corresponds to the basis used by the simplex algorithm.

The set of linear equations C passed to basis should be in the special form produced by simplex[setup]. The function simplex[setup] ensures that each of these variables occurs in exactly one equation, and only on the left-hand side.

The command with(simplex,basis) allows the use of the abbreviated form of this command.