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Contents

Index

• Getting Started

• User's Guide

• Desktop Tools and Development Environment

• Data Import and Export

• Mathematics

• Arrays and Matrices

• Linear Algebra

• Matrix Analysis

• Linear Equations

• Eigenvalues and Singular Values

• Matrix Logarithms and Exponentials

• Factorization

• Elementary Math

• Polynomials

• Interpolation and Computational Geometry

• Cartesian Coordinate System Conversion

• Nonlinear Numerical Methods

• Special Functions

• Sparse Matrices

• Math Constants

• Data Analysis

• Programming and Data Types

• Object-Oriented Programming

• 3-D Visualization

• GUI Development

• External Interfaces

• Release Notes

normest - 2-norm estimate

Syntax

nrm = normest(S) nrm = normest(S,tol) [nrm,count] = normest(...)

Description

This function is intended primarily for sparse matrices, although it works correctly and may be useful for large, full matrices as well.

nrm = normest(S) returns an estimate of the 2-norm of the matrix S.

nrm = normest(S,tol) uses relative error tol instead of the default tolerance 1.e-6. The value of tol determines when the estimate is considered acceptable.

[nrm,count] = normest(...) returns an estimate of the 2-norm and also gives the number of power iterations used.

Algorithms

The power iteration involves repeated multiplication by the matrix S and its transpose, S'. The iteration is carried out until two successive estimates agree to within the specified relative tolerance.

See Also

cond | condest | norm | rcond | svd

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