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MatNormEstimate

Estimate the 2-norm of a matrix.

Synopsis

#include "slepcsys.h" 
PetscErrorCode MatNormEstimate(Mat A,Vec vrn,Vec w,PetscReal *nrm)
Collective

Input Parameters

A  - the matrix
vrn  - random vector with normally distributed entries (can be NULL)
w  - workspace vector (can be NULL)

Output Parameter

nrm  - the norm estimate

Notes

Does not need access to the matrix entries, just performs a matrix-vector product. Based on work by I. Ipsen and coworkers https://ipsen.math.ncsu.edu/ps/slides_ima.pdf

The input vector vrn must have unit 2-norm. If vrn is NULL, then it is created internally and filled with VecSetRandomNormal().

See Also

VecSetRandomNormal()

Level

developer

Location

src/sys/mat/matutil.c

Index of all sys routines
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Index of all manual pages