Version 3.0.0
27th April 2022 User documentation
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 Double
 Double Complex
HSL_MA42_ELEMENT: Unsymmetric finiteelement system: outofcore frontal method (real and complex)
HSL_MA42_ELEMENT
solves one or more sets of sparse linear unsymmetric unassembled finiteelement equations, \(\mathbf{AX} = \mathbf{B}\), or \(\mathbf{A} ^T \mathbf{X} = \mathbf{B}\), or \(\mathbf{A} ^H
\mathbf{X} = \mathbf{B}\), by the frontal method. The system may be real or complex (\(\mathbf{A} ^H\) denotes the conjugate transpose of \(\mathbf{A}\)). There are options for automatically ordering the elements, for supplying the elements using a reverse communication interface, for holding the matrix factors in directaccess files, and for preserving a partial factorization.
The \(n \times n\) coefficient matrix \(\mathbf{A}\) must have a symmetric structure and must be in elemental form
\[\mathbf{A} = \sum _ {k=1} ^ {nelt} \mathbf{A} ^{[k]} ,\] where \(\mathbf{A} ^{[k]}\) is nonzero only in those rows and columns that correspond to variables in the \(k\)th finite element. The elements must be square elements, with the row indices equal to the column indices. For each \(k\), the user must supply a list specifying which rows/columns of \(\mathbf{A}\) are associated with \(\mathbf{A} ^{[k]}\) and an array containing the nonzero entries. The righthand sides \(\mathbf{B}\) may be supplied in elemental form (that is, \(\mathbf{B} = \sum _ {k=1} ^ {nelt} \mathbf{B} ^{[k]}\)) or in assembled form.
Precision: Double  Note: only double precision versions are provided, as we do not recommend this algorithm is used with 4byte arithmetic.