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.math.transform;
018    
019    import org.apache.commons.math.FunctionEvaluationException;
020    import org.apache.commons.math.analysis.UnivariateRealFunction;
021    
022    /**
023     * Interface for one-dimensional data sets transformations producing real results.
024     * <p>Such transforms include {@link FastSineTransformer sine transform},
025     * {@link FastCosineTransformer cosine transform} or {@link
026     * FastHadamardTransformer Hadamard transform}. {@link FastFourierTransformer
027     * Fourier transform} is of a different kind and does not implement this
028     * interface since it produces {@link org.apache.commons.math.complex.Complex complex}
029     * results instead of real ones.
030     * </p>
031     * @version $Revision: 811786 $ $Date: 2009-09-06 05:36:08 -0400 (Sun, 06 Sep 2009) $
032     * @since 2.0
033     */
034    public interface RealTransformer  {
035    
036        /**
037         * Transform the given real data set.
038         * @param f the real data array to be transformed (signal)
039         * @return the real transformed array (spectrum)
040         * @throws IllegalArgumentException if any parameters are invalid
041         */
042        double[] transform(double f[])
043            throws IllegalArgumentException;
044    
045        /**
046         * Transform the given real function, sampled on the given interval.
047         * @param f the function to be sampled and transformed
048         * @param min the lower bound for the interval
049         * @param max the upper bound for the interval
050         * @param n the number of sample points
051         * @return the real transformed array
052         * @throws FunctionEvaluationException if function cannot be evaluated
053         * at some point
054         * @throws IllegalArgumentException if any parameters are invalid
055         */
056        double[] transform(UnivariateRealFunction f, double min, double max, int n)
057            throws FunctionEvaluationException, IllegalArgumentException;
058    
059        /**
060         * Inversely transform the given real data set.
061         * @param f the real data array to be inversely transformed (spectrum)
062         * @return the real inversely transformed array (signal)
063         * @throws IllegalArgumentException if any parameters are invalid
064         */
065        double[] inversetransform(double f[])
066            throws IllegalArgumentException;
067    
068        /**
069         * Inversely transform the given real function, sampled on the given interval.
070         * @param f the function to be sampled and inversely transformed
071         * @param min the lower bound for the interval
072         * @param max the upper bound for the interval
073         * @param n the number of sample points
074         * @return the real inversely transformed array
075         * @throws FunctionEvaluationException if function cannot be evaluated
076         * at some point
077         * @throws IllegalArgumentException if any parameters are invalid
078         */
079        double[] inversetransform(UnivariateRealFunction f, double min, double max, int n)
080            throws FunctionEvaluationException, IllegalArgumentException;
081    
082    }