001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.math3.filter;
018    
019    import org.apache.commons.math3.linear.RealMatrix;
020    
021    /**
022     * Defines the measurement model for the use with a {@link KalmanFilter}.
023     *
024     * @since 3.0
025     * @version $Id: MeasurementModel.java 1416643 2012-12-03 19:37:14Z tn $
026     */
027    public interface MeasurementModel {
028        /**
029         * Returns the measurement matrix.
030         *
031         * @return the measurement matrix
032         */
033        RealMatrix getMeasurementMatrix();
034    
035        /**
036         * Returns the measurement noise matrix. This method is called by the {@link KalmanFilter} every
037         * correction step, so implementations of this interface may return a modified measurement noise
038         * depending on the current iteration step.
039         *
040         * @return the measurement noise matrix
041         * @see KalmanFilter#correct(double[])
042         * @see KalmanFilter#correct(org.apache.commons.math3.linear.RealVector)
043         */
044        RealMatrix getMeasurementNoise();
045    }