HP MLIB User's Guide Vol. 2 7th Ed.

748 HP MLIB LAPACK User’s Guide
The input argument: options
• A, the unput matrix.
• ScalePermstruct->DiagScale, how the previous matrix was row
and/or column scaled.
• ScalePermstruct->R, the row scalings of the previous matix, if any.
• ScalePermstruct->C, the columns scalings of the previous matrix, if
any.
•
ScalePermstruct->perm_r, the row permutation of the previous
matrix.
•
ScalePermstruct->perm_c, the column permutation of the previous
matrix.
• all of LUstruct, the previously computed information about L and U
(the actual numerical values of L and U stored in LUstruct->Llu are
ignored).
The outputs returned include:
• A, the input matrix A overwritten by the scaled and permuted matrix
as described above.
• ScalePermstruct, modified to describe how the input matrix A was
equilibrated (thus Scalepermstruct->DiagScale, R and C may be
modified).
• LUstruct, modified to contain the new L and U factors.
4. The fourth and last value of options->Fact assumes that A is identical to a
matrix that has already been factored on a previous call, and reuses its
entire LU factorization.
• options->Fact = Factored: A is identical to a previously factorized matrix,
so the entire previous factorizatrion can be reused.
In this case all the other options mentioned above are ignored
(options->Equil, options->RowPerm, options->ColPerm,
options->ReplaceTinyPivot).
The user must also supply:
• A, the unfactored matrix, only in the case that iterative refinement is to
be done (specifically A must be the output A from the previous call, so
that it has been scaled and permuted).
• all of ScalePermstruct.
• all of LUstruct, including the actual numerical values of L and U.
all of which are unmodified on output.