I try to use PARDISO as an iterative solver not a direct solver. I have problem for defining IPARMs and DPARMs. I want an example to show hove can i use them and which phases i need to call. I have read the manual and also the example for pardiso_symm_iter.f but in that one, the auther has used default iparm and dparm. In iterative solver do i need to call other phases that phase=3? I want iterative method with conjugate gradient preconditioner . I appreciate if some one can help me.