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().

Level#

developer

Location#

src/sys/mat/matutil.c

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