DSCond#
Compute the condition number.
Synopsis#
#include "slepcds.h"
PetscErrorCode DSCond(DS ds,PetscReal *cond)
Logically Collective
Input Parameters#
ds - the direct solver context
cond - the computed condition number
Notes#
In standard eigenvalue problems, returns the \(\infty\)-norm condition number of the first matrix, computed as \(\kappa_\infty(A) = \|A\|_\infty\|A^{-1}\|_\infty\).
In GSVD problems, returns the maximum of \(\kappa_2(A)\) and \(\kappa_2(B)\), where \(\kappa_2(\cdot)\) is computed as the ratio of the largest and smallest singular values.
Does not take into account the extra row.
See Also#
DS: Direct Solver (or Dense System), DSSolve(), DSSetExtraRow()
Level#
advanced
Location#
Implementations#
DSCond_GSVD() in src/sys/classes/ds/impls/gsvd/dsgsvd.c
DSCond_HEP() in src/sys/classes/ds/impls/hep/dshep.c
DSCond_NHEP() in src/sys/classes/ds/impls/nhep/dsnhep.c
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