MA72: Sparse symmetric finite-element system: out-of-core multiple front method

This collection of subroutines, when used in conjunction with the MA62 package, solves symmetric positive-definite finite-element equations using a multiple front algorithm. It is assumed that the underlying finite-element mesh has been partitioned into (non-overlapping) subdomains. In the multiple front algorithm, a frontal method is applied to each subdomain separately. This may be done in parallel. Using multiple fronts can also have the advantage of requiring less work than applying the frontal method to the whole domain.

MA72 provides routines for generating lists of variables belonging to more than one subdomain, for preserving the partial factorization of a matrix when the sequence of calls to the frontal solver factorization routine MA62B/BD is incomplete, and for performing forward elimination or back-substitution on a subdomain.

MA72 uses reverse communication.

The use of HSL routine MC53 to obtain an efficient element ordering in each subdomain is recommended before MA62 and MA72 are used.

For unsymmetric or symmetric indefinite problems, MA52 should be used in conjunction with MA42.