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

Chapter 15 Sparse Eigenvalues and Eigenvectors 1059
Return eigenvalue/eigenvector results DSEVRC
Name DSEVRC
Return eigenvalue/eigenvector results
Purpose This subprogram retrieves all or selected eigenvalues and eigenvectors after
eigenextraction.
Usage VECLIB:
INTEGER*4 levalu, fstval, lstval, ldevct, ier
REAL*8 evalue(levalu), evectr(ldevct, levalu), global(150)
CALL DSEVRC(levalu, evalue, fstval, lstval, evectr, ldevct, global, ier)
VECLIB8:
INTEGER*8 levalu, fstval, lstval, ldevct, ier
REAL*8 evalue(levalu), evectr(ldevct, levalu), global(150)
CALL DSEVRC(levalu, evalue, fstval, lstval, evectr, ldevct, global, ier)
Input levalu Length of vector for storing eigenvalues.
fstval Ordinal position of first eigenvalue to be returned in
evalue.
lstval Ordinal position of last eigenvalue to be returned in
evalue.
The sign of fstval and lstval determine whether the
eigenvalues returned are from the confirmed set or the
discarded set. Positive indices indicate eigenvalues in
the final confirmed trust region, while negative indices
indicate the discardable set. The following pairs
illustrate the meaning of fstval and lstval:
ldevct The leading dimension of array evectr as declared in
the calling program unit, with ldevct ≥ norder, where
fstval lstval
1 nfound All final trust-region eigenvalues.
−1 −ndiscd All other eigenvalues.
1 −ndiscd All computed eigenvalues.
iii-th final trust-region eigenvalue.
−i −ii-th discardable eigenvalue.
ij
i-th through j-th final trust-region
eigenvalues.
i −j
i-th through nfound-th final
trust-region eigenvalues and 1st
through j-th discardable eigenvalues.