1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 /*
19 * This is not the original file distributed by the Apache Software Foundation
20 * It has been modified by the Hipparchus project
21 */
22 package org.hipparchus.transform;
23
24 import org.hipparchus.analysis.UnivariateFunction;
25 import org.hipparchus.exception.MathIllegalArgumentException;
26
27 /**
28 * Interface for one-dimensional data sets transformations producing real results.
29 * <p>
30 * Such transforms include {@link FastSineTransformer sine transform},
31 * {@link FastCosineTransformer cosine transform} or {@link
32 * FastHadamardTransformer Hadamard transform}. {@link FastFourierTransformer
33 * Fourier transform} is of a different kind and does not implement this
34 * interface since it produces {@link org.hipparchus.complex.Complex}
35 * results instead of real ones.
36 *
37 */
38 public interface RealTransformer {
39
40 /**
41 * Returns the (forward, inverse) transform of the specified real data set.
42 *
43 * @param f the real data array to be transformed (signal)
44 * @param type the type of transform (forward, inverse) to be performed
45 * @return the real transformed array (spectrum)
46 * @throws MathIllegalArgumentException if the array cannot be transformed
47 * with the given type (this may be for example due to array size, which is
48 * constrained in some transforms)
49 */
50 double[] transform(double[] f, TransformType type) throws MathIllegalArgumentException;
51
52 /**
53 * Returns the (forward, inverse) transform of the specified real function,
54 * sampled on the specified interval.
55 *
56 * @param f the function to be sampled and transformed
57 * @param min the (inclusive) lower bound for the interval
58 * @param max the (exclusive) upper bound for the interval
59 * @param n the number of sample points
60 * @param type the type of transform (forward, inverse) to be performed
61 * @return the real transformed array
62 * @throws MathIllegalArgumentException if the lower bound is greater than, or equal to the upper bound
63 * @throws MathIllegalArgumentException if the number of sample points is negative
64 * @throws MathIllegalArgumentException if the sample cannot be transformed
65 * with the given type (this may be for example due to sample size, which is
66 * constrained in some transforms)
67 */
68 double[] transform(UnivariateFunction f, double min, double max, int n,
69 TransformType type)
70 throws MathIllegalArgumentException;
71
72 }