org.ejml.alg.dense.linsol

Class LinearSolverUnrolled

java.lang.Object

org.ejml.alg.dense.linsol.LinearSolverUnrolled

All Implemented Interfaces:

LinearSolver<DenseMatrix64F>

public class LinearSolverUnrolled
extends java.lang.Object
implements LinearSolver<DenseMatrix64F>

Solver which uses an unrolled inverse to compute the inverse. This can only invert matrices and not solve. This is faster than LU inverse but only supports small matrices..

Constructor Summary

Constructors

Constructor and Description
LinearSolverUnrolled()

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(DenseMatrix64F 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(DenseMatrix64F A) Specifies the A matrix in the linear equation.
void	solve(DenseMatrix64F B, DenseMatrix64F X) Solves for X in the linear system, A*X=B.

Methods inherited from class java.lang.Object

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

Constructor Detail

LinearSolverUnrolled

public LinearSolverUnrolled()

Method Detail

setA

public boolean setA(DenseMatrix64F 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<DenseMatrix64F>

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<DenseMatrix64F>

Returns:

The quality of the linear system.

solve

public void solve(DenseMatrix64F B,
                  DenseMatrix64F 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<DenseMatrix64F>

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(DenseMatrix64F 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<DenseMatrix64F>

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<DenseMatrix64F>

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<DenseMatrix64F>

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<DenseMatrix64F>

Type Parameters:

D - Decomposition type

Returns:

Internal decomposition class. If there is none then null.