2 Solvers

A IFEM solver is a subroutine that controls the search for the solution.

Solvers often take extra parameters, which are listed in a type called in C ILSI_Param, which in Fortran is an array of ILSI_PARAM doubles. You initialize these solver parameters using the subroutine ILSI_Param_new, which takes the parameters as its only argument. The input and output parameters in an ILSI_Param are listed in Table 1 and Table 2.

Table 1: ILSI_Param solver input parameters.

C Field Name	Fortran Field Offset	Use
maxResidual	1	If nonzero, termination criteria: magnitude of residual.
maxIterations	2	If nonzero, termination criteria: number of iterations.
solverIn[8]	3-10	Solver-specific input parameters.

Table 2: ILSI_Param solver output parameters.

C Field Name	Fortran Field Offset	Use
residual	11	Magnitude of residual of final solution.
iterations	12	Number of iterations actually taken.
solverOut[8]	13-20	Solver-specific output parameters.