2.3.3.1 Calling the Nonstationary Solvers Directly

The argument lists for all the nonstationary solvers are identical:

      call JT_CG (b, a, ia, ja, iparm, rparm, x,
     &     cpu, rnormt, errt, rnorm, err, ap, iap, jap, status)

Details about new arguments follow:

• rnormt - norm of true residual
  • Type: Real array (0:iparm(_JT_ itmax_))
  • Intent: Out
  • Currently, _JT_itmax_ = 6.

• ap - preconditioner matrix values
  • Type: Real array
  • Intent: In/Out

• iap - integer vector containing info about how ap is stored
  • Type: Integer array
  • Intent: In/Out
  • Currently, _JT_no_of_storage_parameters_ = 8

• jap - integer map for preconditioner
  • Type: Integer array
  • Intent: In/Out

• status - return status
  • Type: Real scalar
  • Intent: In/Out
  • Values:

    -5	$\Longrightarrow$	iteration failed due to breakdown
    -4	$\Longrightarrow$	itmax exceeded
    -3	$\Longrightarrow$	internal error
    -2	$\Longrightarrow$	memory allocation failure
    -1	$\Longrightarrow$	invalid argument(s)
    0	$\Longrightarrow$	convergence was achieved
    >0	$\Longrightarrow$	preconditioning needed