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 * http://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 package org.apache.commons.math4.transform;
18
19 import java.util.function.DoubleUnaryOperator;
20 import java.util.function.UnaryOperator;
21
22 /**
23 * Real transforms.
24 */
25 public interface RealTransform extends UnaryOperator<double[]> {
26 /**
27 * Returns the transform of the specified data set.
28 *
29 * @param f the data array to be transformed (signal).
30 * @return the transformed array (spectrum).
31 * @throws IllegalArgumentException if the transform cannot be performed.
32 */
33 @Override
34 double[] apply(double[] f);
35
36 /**
37 * Returns the transform of the specified function.
38 *
39 * @param f Function to be sampled and transformed.
40 * @param min Lower bound (inclusive) of the interval.
41 * @param max Upper bound (exclusive) of the interval.
42 * @param n Number of sample points.
43 * @return the result.
44 * @throws IllegalArgumentException if the transform cannot be performed.
45 */
46 default double[] apply(DoubleUnaryOperator f,
47 double min,
48 double max,
49 int n) {
50 return apply(TransformUtils.sample(f, min, max, n));
51 }
52 }