The solve procedures operate on a global matrix produced by an assembly command. Various solvers are invoked as follows
| solve | for the direct solver |
| itsolve 1 | for GMRES |
| itsolve 2 | for BiCGSTAB |
| itsolve 3 | for conjugate gradient |
Note that itsolve 3 works for symmetric positive definite matrices, and itsolve 1 and itsolve 2 for unsymmetric matrices. You can also split solve into two operations
fact resolve
This is efficient if you have repeated operations using the same matrix. The factors can be stored using saveF or getF.