| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.math4.legacy.analysis.interpolation; |
| |
| import org.apache.commons.math4.legacy.analysis.BivariateFunction; |
| import org.apache.commons.statistics.distribution.ContinuousDistribution; |
| import org.apache.commons.statistics.distribution.UniformContinuousDistribution; |
| import org.apache.commons.math4.legacy.exception.DimensionMismatchException; |
| import org.apache.commons.math4.legacy.exception.MathIllegalArgumentException; |
| import org.apache.commons.rng.UniformRandomProvider; |
| import org.apache.commons.rng.simple.RandomSource; |
| import org.junit.Assert; |
| import org.junit.Test; |
| |
| /** |
| * Test case for the bicubic interpolator. |
| */ |
| public final class BicubicInterpolatorTest { |
| /** |
| * Test preconditions. |
| */ |
| @Test |
| public void testPreconditions() { |
| double[] xval = new double[] {3, 4, 5, 6.5}; |
| double[] yval = new double[] {-4, -3, -1, 2.5}; |
| double[][] zval = new double[xval.length][yval.length]; |
| |
| BivariateGridInterpolator interpolator = new BicubicInterpolator(); |
| |
| @SuppressWarnings("unused") |
| BivariateFunction p = interpolator.interpolate(xval, yval, zval); |
| |
| double[] wxval = new double[] {3, 2, 5, 6.5}; |
| try { |
| p = interpolator.interpolate(wxval, yval, zval); |
| Assert.fail("an exception should have been thrown"); |
| } catch (MathIllegalArgumentException e) { |
| // Expected |
| } |
| |
| double[] wyval = new double[] {-4, -3, -1, -1}; |
| try { |
| p = interpolator.interpolate(xval, wyval, zval); |
| Assert.fail("an exception should have been thrown"); |
| } catch (MathIllegalArgumentException e) { |
| // Expected |
| } |
| |
| double[][] wzval = new double[xval.length][yval.length + 1]; |
| try { |
| p = interpolator.interpolate(xval, yval, wzval); |
| Assert.fail("an exception should have been thrown"); |
| } catch (DimensionMismatchException e) { |
| // Expected |
| } |
| wzval = new double[xval.length - 1][yval.length]; |
| try { |
| p = interpolator.interpolate(xval, yval, wzval); |
| Assert.fail("an exception should have been thrown"); |
| } catch (DimensionMismatchException e) { |
| // Expected |
| } |
| } |
| |
| /** |
| * Interpolating a plane. |
| * <p> |
| * z = 2 x - 3 y + 5 |
| */ |
| @Test |
| public void testPlane() { |
| BivariateFunction f = new BivariateFunction() { |
| @Override |
| public double value(double x, double y) { |
| return 2 * x - 3 * y + 5; |
| } |
| }; |
| |
| testInterpolation(3000, |
| 1e-13, |
| f, |
| false); |
| } |
| |
| /** |
| * Interpolating a paraboloid. |
| * <p> |
| * z = 2 x<sup>2</sup> - 3 y<sup>2</sup> + 4 x y - 5 |
| */ |
| @Test |
| public void testParaboloid() { |
| BivariateFunction f = new BivariateFunction() { |
| @Override |
| public double value(double x, double y) { |
| return 2 * x * x - 3 * y * y + 4 * x * y - 5; |
| } |
| }; |
| |
| testInterpolation(3000, |
| 1e-12, |
| f, |
| false); |
| } |
| |
| /** |
| * @param numSamples Number of test samples. |
| * @param tolerance Allowed tolerance on the interpolated value. |
| * @param f Test function. |
| * @param print Whether to print debugging output to the console. |
| */ |
| private void testInterpolation(int numSamples, |
| double tolerance, |
| BivariateFunction f, |
| boolean print) { |
| final int sz = 21; |
| final double[] xval = new double[sz]; |
| final double[] yval = new double[sz]; |
| // Coordinate values |
| final double delta = 1d / (sz - 1); |
| for (int i = 0; i < sz; i++) { |
| xval[i] = -1 + 15 * i * delta; |
| yval[i] = -20 + 30 * i * delta; |
| } |
| |
| final double[][] zval = new double[xval.length][yval.length]; |
| for (int i = 0; i < xval.length; i++) { |
| for (int j = 0; j < yval.length; j++) { |
| zval[i][j] = f.value(xval[i], yval[j]); |
| } |
| } |
| |
| final BicubicInterpolator interpolator = new BicubicInterpolator(); |
| final BicubicInterpolatingFunction p = interpolator.interpolate(xval, yval, zval); |
| |
| final UniformRandomProvider rng = RandomSource.WELL_19937_C.create(); |
| final ContinuousDistribution.Sampler distX = UniformContinuousDistribution.of(xval[0], xval[xval.length - 1]).createSampler(rng); |
| final ContinuousDistribution.Sampler distY = UniformContinuousDistribution.of(yval[0], yval[yval.length - 1]).createSampler(rng); |
| |
| int count = 0; |
| while (true) { |
| double x = distX.sample(); |
| double y = distY.sample(); |
| if (!p.isValidPoint(x, y)) { |
| if (print) { |
| System.out.println("# " + x + " " + y); |
| } |
| continue; |
| } |
| |
| if (count++ > numSamples) { |
| break; |
| } |
| final double expected = f.value(x, y); |
| final double actual = p.value(x, y); |
| |
| if (print) { |
| System.out.println(x + " " + y + " " + expected + " " + actual); |
| } |
| |
| Assert.assertEquals(expected, actual, tolerance); |
| } |
| } |
| } |