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

Chapter 15 Sparse Eigenvalues and Eigenvectors 1057
Reordering and symbolic factorization DSEVOR
Name DSEVOR
Reordering and symbolic factorization
Purpose This subprogram reorders the matrix whose pattern of nonzeros is given by the
locations where either A or B is nonzero, such that an efficient sparse
factorization of such a matrix can be obtained. DSEVOR then constructs data
structures required for the sparse factorization.
Usage VECLIB:
INTEGER*4 ier
REAL*8 global(150)
CALL DSEVOR(global, ier)
VECLIB8:
INTEGER*8 ier
REAL*8 global(150)
CALL DSEVOR(global, ier)
Output global Global communications array for this problem. This
array must be passed, untouched by the user, to
successive subroutines in this package.
ier Status response:
ier = 0 Normal return.
ier = −200 Incorrect processing path; structure
input not completed, or value input
subroutines already called.
ier = −201 Error in dynamic storage allocation.
ier = −301 Error in dynamic storage allocation.
ier = −302 Illegal error.
Example The structure of the sparse matrices in a sparse eigenvalue problem have been
communicated to the eigenanalysis package using DSEVIN followed by
DSEVIM or DSEVIC or the following: DSEVI1, DSEVIE and DSEVIF. The next
step is the process to obtain good reordering for the factorizations that will be
needed in the eigenextraction process.
INTEGER*4 IER
REAL*8 GLOBAL(150)
CALL DSEVOR (GLOBAL,IER)
IF ( IER .NE. 0 ) THEN
handle error condition
ENDIF