bicg bicg1 bicg_r cgs cgs_r diom diom_r dqgmres dqgmres_r fgmres fgmres_r fom fom_r gcr gcr_r gpbicg gpbicg_r orthomin orthomin_r qmr qmr_r sor sor_r tfqmr tfqmr_r

fom() void fom ( int  n, void(*)(int, const double[], double[])  matvec, void(*)(int, const double[], double[])  psolve, void(*)(int, const double[], double, int, int *)  chkconv, const double  b[], double  x[], int  m, int  maxiter, int *  iter, double *  res, int  lwork, double  work[], int *  info  ) Solution of linear system Ax = b using full orthogonalization method (FOM) Purpose This routine solves the linear system Ax = b using the full orthogonalization iterative method (FOM) with preconditioning. Parameters [in] n Dimension of the matrix. (n >= 0) (If n = 0, returns without computation) [in] matvec User supplied subroutine which calculates the matrix and vector product as follows. code void matvec(int n, const double x[], double y[]) { Compute A*x, and return result in y[]. } endcode [in] psolve User supplied subroutine which perform the preconditioner solve routine for the linear system M*x = b as follows, where M is a preconditioner metrix. code void psolve(int n, const double b[], double x[]) { Solve M*x = b, and return solution in x[]. } endcode [in] chkconv User supplied subroutine which is called on every iteration for the convergence test as follows, where x[] is the current approximate solution, res is the current residual norm norm(b - A*x), and iter is the current number of iterations. This routine can also be used to output the intermediate results. code void chkconv(int n, const double x[], double res, int iter, int *ichk) { Set *ichk = 1 if converged. Otherwise, set *ichk = 0. } endcode [in] b[] Array b[lb] (lb >= n) Right hand side vector b. [in,out] x[] Array x[lx] (lx >= n) [in] Initial guess of solution. [out] Obtained approximate solution. [in] m Restart parameter. (0 < m <= n) [in] maxiter Maximum number of iterations. (maxiter > 0) [out] iter Final number of iterations. [out] res Final residual norm norm(b - A*x). [in] lwork Size of array work[]. (lwork >= (m + 6)*n + (m + 2)*m) [out] work[] Array work[lwork] Work array. [out] info = 0: Successful exit < 0: The (-info)-th argument is invalid. = 11: Maximum number of iterations exceeded. = 12: Breakdown occurred.