org.apache.commons.math.linear
Class RealLinearOperator

java.lang.Object
  org.apache.commons.math.linear.RealLinearOperator

Direct Known Subclasses:

AbstractRealMatrix, InvertibleRealLinearOperator

public abstract class RealLinearOperator
extends java.lang.Object

This class defines a linear operator operating on real (double) vector spaces. No direct access to the coefficients of the underlying matrix is provided. The motivation for such an interface is well stated by Barrett et al. (1994):

We restrict ourselves to iterative methods, which work by repeatedly improving an approximate solution until it is accurate enough. These methods access the coefficient matrix A of the linear system only via the matrix-vector product y = A x (and perhaps z = A^T x). Thus the user need only supply a subroutine for computing y (and perhaps z) given x, which permits full exploitation of the sparsity or other special structure of A.

Barret et al. (1994)

R. Barrett, M. Berry, T. F. Chan, J. Demmel, J. M. Donato, J. Dongarra, V. Eijkhout, R. Pozo, C. Romine and H. Van der Vorst, Templates for the Solution of Linear Systems: Building Blocks for Iterative Methods, SIAM

Since:

3.0

Version:

$Id: RealLinearOperator.java 1178072 2011-10-01 19:06:52Z celestin $

Constructor Summary

RealLinearOperator()

Method Summary

abstract int	getColumnDimension() Returns the dimension of the domain of this operator.
abstract int	getRowDimension() Returns the dimension of the codomain of this operator.
abstract RealVector	operate(RealVector x) Returns the result of multiplying this by the vector x.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RealLinearOperator

public RealLinearOperator()

Method Detail

getRowDimension

public abstract int getRowDimension()

Returns the dimension of the codomain of this operator.

Returns:

the number of rows of the underlying matrix.

getColumnDimension

public abstract int getColumnDimension()

Returns the dimension of the domain of this operator.

Returns:

the number of columns of the underlying matrix.

operate

public abstract RealVector operate(RealVector x)

Returns the result of multiplying this by the vector x.

Parameters:

x - Vector to operate on.

Returns:

the product of this instance with x.

Throws:

DimensionMismatchException - if the column dimension does not match the size of x.