slepc-3.22.1 2024-10-28
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# VecCheckOrthogonality

Checks (or prints) the level of (bi-)orthogonality of a set of vectors.

### Synopsis

    #include "slepcvec.h"
    PetscErrorCode VecCheckOrthogonality(Vec V[],PetscInt nv,Vec W[],PetscInt nw,Mat B,PetscViewer viewer,PetscReal *lev)

Collective

### Input Parameters

| V | - a set of vectors
| nv | - number of V vectors
| W | - an alternative set of vectors (optional)
| nw | - number of W vectors
| B | - matrix defining the inner product (optional)
| viewer | - optional visualization context

### Output Parameter

| lev | - level of orthogonality (optional)

### Notes

This function computes W'*V and prints the result. It is intended to check the level of bi-orthogonality of the vectors in the two sets. If W is equal to NULL then V is used, thus checking the orthogonality of the V vectors.

If matrix B is provided then the check uses the B-inner product, W'*B*V.

If lev is not NULL, it will contain the maximum entry of matrix W'*V - I (in absolute value) omitting the diagonal. Otherwise, the matrix W'*V is printed.

### See Also

VecCheckOrthonormality()

### Level

developer

### Location

src/sys/vec/vecutil.c

### Examples

src/eps/tutorials/ex41.c
src/eps/tutorials/ex55.c
Index of all sys routines
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Index of all manual pages