slepc-3.22.1 2024-10-28
BVSetDefiniteTolerance
Set the tolerance to be used when checking a definite inner product.
Synopsis
#include "slepcbv.h"
PetscErrorCode BVSetDefiniteTolerance(BV bv,PetscReal deftol)
Logically Collective
Input Parameters
| bv | - basis vectors
|
| deftol | - the tolerance
|
Options Database Key
| -bv_definite_tol <deftol> | - the tolerance
|
Notes
When using a non-standard inner product, see BVSetMatrix(), the solver needs
to compute sqrt(z'*B*z) for various vectors z. If the inner product has not
been declared indefinite, the value z'*B*z must be positive, but due to
rounding error a tiny value may become negative. A tolerance is used to
detect this situation. Likewise, in complex arithmetic z'*B*z should be
real, and we use the same tolerance to check whether a nonzero imaginary part
can be considered negligible.
This function sets this tolerance, which defaults to 10*eps, where eps is
the machine epsilon. The default value should be good for most applications.
See Also
BVSetMatrix()
Level
advanced
Location
src/sys/classes/bv/interface/bvbasic.c
Index of all BV routines
Table of Contents for all manual pages
Index of all manual pages