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    import org.apache.commons.math.complex.Complex;
022    
023    /**
024     * Interface for one-dimensional data sets transformations producing real results.
025     * <p>Such transforms include {@link FastSineTransformer sine transform},
026     * {@link FastCosineTransformer cosine transform} or {@link
027     * FastHadamardTransformer Hadamard transform}. {@link FastFourierTransformer
028     * Fourier transform} is of a different kind and does not implement this
029     * interface since it produces {@link Complex complex} results instead of real
030     * ones.
031     * </p>
032     * @version $Revision: 780541 $ $Date: 2009-05-31 20:47:02 -0400 (Sun, 31 May 2009) $
033     * @since 2.0
034     */
035    public interface RealTransformer  {
036    
037        /**
038         * Transform the given real data set.
039         * @param f the real data array to be transformed (signal)
040         * @return the real transformed array (spectrum)
041         * @throws IllegalArgumentException if any parameters are invalid
042         */
043        double[] transform(double f[])
044            throws IllegalArgumentException;
045    
046        /**
047         * Transform the given real function, sampled on the given interval.
048         * @param f the function to be sampled and transformed
049         * @param min the lower bound for the interval
050         * @param max the upper bound for the interval
051         * @param n the number of sample points
052         * @return the real transformed array
053         * @throws FunctionEvaluationException if function cannot be evaluated
054         * at some point
055         * @throws IllegalArgumentException if any parameters are invalid
056         */
057        double[] transform(UnivariateRealFunction f, double min, double max, int n)
058            throws FunctionEvaluationException, IllegalArgumentException;
059    
060        /**
061         * Inversely transform the given real data set.
062         * @param f the real data array to be inversely transformed (spectrum)
063         * @return the real inversely transformed array (signal)
064         * @throws IllegalArgumentException if any parameters are invalid
065         */
066        public abstract double[] inversetransform(double f[])
067            throws IllegalArgumentException;
068    
069        /**
070         * Inversely transform the given real function, sampled on the given interval.
071         * @param f the function to be sampled and inversely transformed
072         * @param min the lower bound for the interval
073         * @param max the upper bound for the interval
074         * @param n the number of sample points
075         * @return the real inversely transformed array
076         * @throws FunctionEvaluationException if function cannot be evaluated
077         * at some point
078         * @throws IllegalArgumentException if any parameters are invalid
079         */
080        double[] inversetransform(UnivariateRealFunction f, double min, double max, int n)
081            throws FunctionEvaluationException, IllegalArgumentException;
082    
083    }