org.ejml.alg.dense.linsol

Class LinearSolverSafe<T extends ReshapeMatrix>

java.lang.Object

org.ejml.alg.dense.linsol.LinearSolverSafe<T>

All Implemented Interfaces:

LinearSolver<T>

public class LinearSolverSafe<T extends ReshapeMatrix>
extends java.lang.Object
implements LinearSolver<T>

Ensures that any linear solver it is wrapped around will never modify the input matrices.

Constructor Summary

Constructors

Constructor and Description
LinearSolverSafe(LinearSolver<T> alg)

Method Summary

Modifier and Type	Method and Description
<D extends DecompositionInterface> D	getDecomposition() If a decomposition class was used internally then this will return that class.
void	invert(T A_inv) Computes the inverse of of the 'A' matrix passed into LinearSolver.setA(org.ejml.data.Matrix) and writes the results to the provided matrix.
boolean	modifiesA() Returns true if the passed in matrix to LinearSolver.setA(org.ejml.data.Matrix) is modified.
boolean	modifiesB() Returns true if the passed in 'B' matrix to LinearSolver.solve(org.ejml.data.Matrix, org.ejml.data.Matrix) is modified.
double	quality() Returns a very quick to compute measure of how singular the system is.
boolean	setA(T A) Specifies the A matrix in the linear equation.
void	solve(T B, T X) Solves for X in the linear system, A*X=B.

Methods inherited from class java.lang.Object

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

Constructor Detail

LinearSolverSafe

public LinearSolverSafe(LinearSolver<T> alg)

Parameters:

alg - The solver it is wrapped around.

Method Detail

setA

public boolean setA(T A)

Description copied from interface: LinearSolver

Specifies the A matrix in the linear equation. A reference might be saved and it might also be modified depending on the implementation. If it is modified then LinearSolver.modifiesA() will return true.

If this value returns true that does not guarantee a valid solution was generated. This is because some decompositions don't detect singular matrices.

Specified by:

setA in interface LinearSolver<T extends ReshapeMatrix>

Parameters:

A - The 'A' matrix in the linear equation. Might be modified or save the reference.

Returns:

true if it can be processed.

quality

public double quality()

Description copied from interface: LinearSolver

Returns a very quick to compute measure of how singular the system is. This measure will be invariant to the scale of the matrix and always be positive, with larger values indicating it is less singular. If not supported by the solver then the runtime exception IllegalArgumentException is thrown. This is NOT the matrix's condition.

How this function is implemented is not specified. One possible implementation is the following: In many decompositions a triangular matrix is extracted. The determinant of a triangular matrix is easily computed and once normalized to be scale invariant and its absolute value taken it will provide functionality described above.

Specified by:

quality in interface LinearSolver<T extends ReshapeMatrix>

Returns:

The quality of the linear system.

solve

public void solve(T B,
                  T X)

Description copied from interface: LinearSolver

Solves for X in the linear system, A*X=B.

In some implementations 'B' and 'X' can be the same instance of a variable. Call LinearSolver.modifiesB() to determine if 'B' is modified.

Specified by:

solve in interface LinearSolver<T extends ReshapeMatrix>

Parameters:

B - A matrix ℜ ^{m × p}. Might be modified.

X - A matrix ℜ ^{n × p}, where the solution is written to. Modified.

invert

public void invert(T A_inv)

Description copied from interface: LinearSolver

Computes the inverse of of the 'A' matrix passed into LinearSolver.setA(org.ejml.data.Matrix) and writes the results to the provided matrix. If 'A_inv' needs to be different from 'A' is implementation dependent.

Specified by:

invert in interface LinearSolver<T extends ReshapeMatrix>

Parameters:

A_inv - Where the inverted matrix saved. Modified.

modifiesA

public boolean modifiesA()

Description copied from interface: LinearSolver

Returns true if the passed in matrix to LinearSolver.setA(org.ejml.data.Matrix) is modified.

Specified by:

modifiesA in interface LinearSolver<T extends ReshapeMatrix>

Returns:

true if A is modified in setA().

modifiesB

public boolean modifiesB()

Description copied from interface: LinearSolver

Returns true if the passed in 'B' matrix to LinearSolver.solve(org.ejml.data.Matrix, org.ejml.data.Matrix) is modified.

Specified by:

modifiesB in interface LinearSolver<T extends ReshapeMatrix>

Returns:

true if B is modified in solve(B,X).

getDecomposition

public <D extends DecompositionInterface> D getDecomposition()

Description copied from interface: LinearSolver

If a decomposition class was used internally then this will return that class. Most linear solvers decompose the input matrix into a more simplistic form. However some solutions do not require decomposition, e.g. inverse by minor.

Specified by:

getDecomposition in interface LinearSolver<T extends ReshapeMatrix>

Type Parameters:

D - Decomposition type

Returns:

Internal decomposition class. If there is none then null.