1 /* Copyright 2002-2020 CS GROUP
2 * Licensed to CS GROUP (CS) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * CS 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.orekit.propagation.semianalytical.dsst.utilities;
18
19 import org.hipparchus.util.FastMath;
20
21 /** Interpolation grid where points obey a maximum time gap.
22 * <p>
23 * The grid is adapted to the step considered,
24 * meaning that for short steps, the grid will have numerous points.
25 * </p>
26 *
27 * @author Luc Maisonobe
28 * @since 7.1
29 */
30 public class MaxGapInterpolationGrid implements InterpolationGrid {
31
32 /** Maximum time gap. */
33 private final double maxGap;
34
35 /** Constructor.
36 * @param maxGap maximum time gap between interpolation points
37 */
38 public MaxGapInterpolationGrid(final double maxGap) {
39 this.maxGap = maxGap;
40 }
41
42 /** {@inheritDoc} */
43 @Override
44 public double[] getGridPoints(final double stepStart, final double stepEnd) {
45 final int pointsPerStep = FastMath.max(2, (int) FastMath.ceil(FastMath.abs(stepEnd - stepStart) / maxGap));
46 final double[] grid = new double[pointsPerStep];
47
48 final double stepSize = (stepEnd - stepStart) / (pointsPerStep - 1);
49 for (int i = 0; i < pointsPerStep; i++) {
50 grid[i] = stepSize * i + stepStart;
51 }
52
53 return grid;
54 }
55 }