RealLinearOperator (Hipparchus 1.3 API)

All Known Implementing Classes:

AbstractRealMatrix, Array2DRowRealMatrix, BlockRealMatrix, DiagonalMatrix, JacobiPreconditioner, OpenMapRealMatrix
```
public interface 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

Method Summary

All Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method	Description
`int`	`getColumnDimension()`	Returns the dimension of the domain of this operator.
`int`	`getRowDimension()`	Returns the dimension of the codomain of this operator.
`default boolean`	`isTransposable()`	Returns `true` if this operator supports `operateTranspose(RealVector)`.
`RealVector`	`operate(RealVector x)`	Returns the result of multiplying `this` by the vector `x`.
`default RealVector`	`operateTranspose(RealVector x)`	Returns the result of multiplying the transpose of `this` operator by the vector `x` (optional operation).

- Method Detail
  - getRowDimension
```
int getRowDimension()
```
    Returns the dimension of the codomain of this operator.
    
    Returns:
    
    the number of rows of the underlying matrix
  - getColumnDimension
```
int getColumnDimension()
```
    Returns the dimension of the domain of this operator.
    
    Returns:
    
    the number of columns of the underlying matrix
  - operate
```
RealVector operate(RealVector x)
            throws MathIllegalArgumentException
```
    Returns the result of multiplying this by the vector x.
    
    Parameters:
    
    x - the vector to operate on
    
    Returns:
    
    the product of this instance with x
    
    Throws:
    
    MathIllegalArgumentException - if the column dimension does not match the size of x
  - operateTranspose
```
default RealVector operateTranspose(RealVector x)
                             throws MathIllegalArgumentException,
                                    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 - the vector to operate on
    
    Returns:
    
    the product of the transpose of this instance with x
    
    Throws:
    
    MathIllegalArgumentException - if the row dimension does not match the size of x
    
    UnsupportedOperationException - if this operation is not supported by this operator
  - isTransposable
```
default 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:
    
    false

Interface RealLinearOperator

Method Summary

Method Detail

getRowDimension

getColumnDimension

operate

operateTranspose

isTransposable