org.hipparchus.linear.IterativeLinearSolverEvent Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* This is not the original file distributed by the Apache Software Foundation
* It has been modified by the Hipparchus project
*/
package org.hipparchus.linear;
import org.hipparchus.exception.LocalizedCoreFormats;
import org.hipparchus.exception.MathRuntimeException;
import org.hipparchus.util.IterationEvent;
/**
* This is the base class for all events occurring during the iterations of a
* {@link IterativeLinearSolver}.
*
*/
public abstract class IterativeLinearSolverEvent
extends IterationEvent {
/** Serialization identifier. */
private static final long serialVersionUID = 20120129L;
/**
* Creates a new instance of this class.
*
* @param source the iterative algorithm on which the event initially
* occurred
* @param iterations the number of iterations performed at the time
* {@code this} event is created
*/
public IterativeLinearSolverEvent(final Object source, final int iterations) {
super(source, iterations);
}
/**
* Returns the current right-hand side of the linear system to be solved.
* This method should return an unmodifiable view, or a deep copy of the
* actual right-hand side vector, in order not to compromise subsequent
* iterations of the source {@link IterativeLinearSolver}.
*
* @return the right-hand side vector, b
*/
public abstract RealVector getRightHandSideVector();
/**
* Returns the norm of the residual. The returned value is not required to
* be exact. Instead, the norm of the so-called updated
* residual (if available) should be returned. For example, the
* {@link ConjugateGradient conjugate gradient} method computes a sequence
* of residuals, the norm of which is cheap to compute. However, due to
* accumulation of round-off errors, this residual might differ from the
* true residual after some iterations. See e.g. A. Greenbaum and
* Z. Strakos, Predicting the Behavior of Finite Precision Lanzos and
* Conjugate Gradient Computations, Technical Report 538, Department of
* Computer Science, New York University, 1991 (available
* here).
*
* @return the norm of the residual, ||r||
*/
public abstract double getNormOfResidual();
/**
*
* Returns the residual. This is an optional operation, as all iterative
* linear solvers do not provide cheap estimate of the updated residual
* vector, in which case
*
*
* - this method should throw a
* {@link MathRuntimeException},
* - {@link #providesResidual()} returns {@code false}.
*
*
* The default implementation throws a
* {@link MathRuntimeException}. If this method is overriden,
* then {@link #providesResidual()} should be overriden as well.
*
*
* @return the updated residual, r
*/
public RealVector getResidual() {
throw new MathRuntimeException(LocalizedCoreFormats.UNSUPPORTED_OPERATION);
}
/**
* Returns the current estimate of the solution to the linear system to be
* solved. This method should return an unmodifiable view, or a deep copy of
* the actual current solution, in order not to compromise subsequent
* iterations of the source {@link IterativeLinearSolver}.
*
* @return the solution, x
*/
public abstract RealVector getSolution();
/**
* Returns {@code true} if {@link #getResidual()} is supported. The default
* implementation returns {@code false}.
*
* @return {@code false} if {@link #getResidual()} throws a
* {@link MathRuntimeException}
*/
public boolean providesResidual() {
return false;
}
}