Apache Commons Math 3.6.1 · org.apache.commons.math3.linear.RealLinearOperator

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

Constructor Summary

Access	Constructor and Description
public	RealLinearOperator()

Method Summary

Modifier and Type	Method and Description
public abstract int	Returns: the number of columns of the underlying matrix getColumnDimension() Returns the dimension of the domain of this operator.
public abstract int	Returns: the number of rows of the underlying matrix getRowDimension() Returns the dimension of the codomain of this operator.
public boolean	Returns: `false` isTransposable() Returns `true` if this operator supports `operateTranspose(RealVector)`.
public abstract RealVector	Returns: the product of `this` instance with `x` operate(final RealVector the vector to operate on x) Returns the result of multiplying `this` by the vector `x`.
public RealVector	Returns: the product of the transpose of `this` instance with `x` operateTranspose(final RealVector the vector to operate on x) Returns the result of multiplying the transpose of `this` operator by the vector `x` (optional operation).

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Constructor Detail

RealLinearOperator	back to summary
public RealLinearOperator()

Method Detail

getColumnDimension	back to summary
public abstract int getColumnDimension() Returns the dimension of the domain of this operator. Returns:int the number of columns of the underlying matrix

getColumnDimension

back to summary

public abstract int getColumnDimension()

Returns the dimension of the domain of this operator.

Returns:int: the number of columns of the underlying matrix

getRowDimension	back to summary
public abstract int getRowDimension() Returns the dimension of the codomain of this operator. Returns:int the number of rows of the underlying matrix

getRowDimension

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public abstract int getRowDimension()

Returns the dimension of the codomain of this operator.

Returns:int: the number of rows of the underlying matrix

isTransposable back to summary

isTransposable	back to summary
public boolean isTransposable() Returns `true` if this operator supports `operateTranspose(RealVector)`. If `true` is returned, `operateTranspose(RealVector)` should not throw `UnsupportedOperationException`. The default implementation returns `false`. Returns:boolean `false`

public boolean isTransposable()

Returns true if this operator supports operateTranspose(RealVector). If true is returned, operateTranspose(RealVector) should not throw UnsupportedOperationException. The default implementation returns false.

Returns:boolean: false

operate back to summary

operate	back to summary
public abstract RealVector operate(final RealVector x) throws DimensionMismatchException Returns the result of multiplying `this` by the vector `x`. Parameters x:RealVector the vector to operate on Returns:RealVector the product of `this` instance with `x` Exceptions DimensionMismatchException: if the column dimension does not match the size of `x`

public abstract RealVector operate(final RealVector x) throws DimensionMismatchException

Returns the result of multiplying this by the vector x.

Parameters

x:RealVector: the vector to operate on

Returns:RealVector

the product of this instance with x

Exceptions

DimensionMismatchException:: if the column dimension does not match the size of x

operateTranspose back to summary

operateTranspose	back to summary
public RealVector operateTranspose(final RealVector x) throws DimensionMismatchException, UnsupportedOperationException Returns the result of multiplying the transpose of `this` operator by the vector `x` (optional operation). The default implementation throws an `UnsupportedOperationException`. Users overriding this method must also override `isTransposable()`. Parameters x:RealVector the vector to operate on Returns:RealVector the product of the transpose of `this` instance with `x` Exceptions DimensionMismatchException: if the row dimension does not match the size of `x` UnsupportedOperationException: if this operation is not supported by `this` operator

public RealVector operateTranspose(final RealVector x) throws DimensionMismatchException, UnsupportedOperationException

Returns the result of multiplying the transpose of this operator by the vector x (optional operation). The default implementation throws an UnsupportedOperationException. Users overriding this method must also override isTransposable().