5.2.3 rparm(_JT_ omega_) - relaxation parameter

• Current index: 3
• Intent: In
• Default: _JT_ omega_ default_ (currently 1.0)
• This parameter is used for separate and distinct purposes depending on other options.
  • For JT_ STATIONARY, which implements the stationary iterative methods (Jacobi, SOR, SSOR), it is simply the standard relaxation parameter, with an acceptable range of 0 < $\omega$ < 2.

  • For multistep preconditioners (iparm(_JT_ pre_) = _JT_ pre_ Jacobi_ or _JT_ pre_ SSOR_), it also serves as the standard relaxation parameter, again with an acceptable range of 0 < $\omega$ < 2.

  • For incomplete factorization preconditioners (iparm(_JT_ pre_) = _JT_ pre_ IC_ or _JT_ pre_ ILU_), it controls the degree to which fill-in elements are added back into the diagonal:

    rparm(_JT_ omega_)	Meaning
    0	standard incomplete factorization
    1	modified incomplete factorization
    0 < $\omega$ < 1	relaxed incomplete factorization

    Note that in this case the acceptable range is 0 < $\omega$ < 1.