Java example source code file (MicrosphereInterpolatorTest.java)

This example Java source code file (MicrosphereInterpolatorTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

deprecated, illegalargumentexception, microsphereinterpolator, microsphereinterpolatortest, multivariatefunction, multivariateinterpolator, test

The MicrosphereInterpolatorTest.java Java example source code

/*
 * 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.math3.analysis.interpolation;

import org.apache.commons.math3.analysis.MultivariateFunction;
import org.apache.commons.math3.util.FastMath;
import org.junit.Assert;
import org.junit.Test;

/**
 * Test case for the "microsphere projection" interpolator.
 *
 * @deprecated Code will be removed in 4.0.  Use {@link InterpolatingMicrosphere}
 * and {@link MicrosphereProjectionInterpolator} instead.
 */
@Deprecated
public final class MicrosphereInterpolatorTest {
    /**
     * Test of interpolator for a plane.
     * <p>
     * y = 2 x<sub>1 - 3 x2 + 5
     */
    @Test
    public void testLinearFunction2D() {
        MultivariateFunction f = new MultivariateFunction() {
                public double value(double[] x) {
                    if (x.length != 2) {
                        throw new IllegalArgumentException();
                    }
                    return 2 * x[0] - 3 * x[1] + 5;
                }
            };

        MultivariateInterpolator interpolator = new MicrosphereInterpolator();

        // Interpolating points in [-1, 1][-1, 1] by steps of 1.
        final int n = 9;
        final int dim = 2;
        double[][] x = new double[n][dim];
        double[] y = new double[n];
        int index = 0;
        for (int i = -1; i <= 1; i++) {
            for (int j = -1; j <= 1; j++) {
                x[index][0] = i;
                x[index][1] = j;
                y[index] = f.value(x[index]);
                ++index;
            }
        }

        MultivariateFunction p = interpolator.interpolate(x, y);

        double[] c = new double[dim];
        double expected, result;

        c[0] = 0;
        c[1] = 0;
        expected = f.value(c);
        result = p.value(c);
        Assert.assertEquals("On sample point", expected, result, FastMath.ulp(1d));

        c[0] = 0 + 1e-5;
        c[1] = 1 - 1e-5;
        expected = f.value(c);
        result = p.value(c);
        Assert.assertEquals("1e-5 away from sample point", expected, result, 1e-4);
    }

    /**
     * Test of interpolator for a quadratic function.
     * <p>
     * y = 2 x<sub>12 - 3 x22
     *     + 4 x<sub>1 x2 - 5
     */
    @Test
    public void testParaboloid2D() {
        MultivariateFunction f = new MultivariateFunction() {
                public double value(double[] x) {
                    if (x.length != 2) {
                        throw new IllegalArgumentException();
                    }
                    return 2 * x[0] * x[0] - 3 * x[1] * x[1] + 4 * x[0] * x[1] - 5;
                }
            };

        MultivariateInterpolator interpolator = new MicrosphereInterpolator();

        // Interpolating points in [-10, 10][-10, 10] by steps of 2.
        final int n = 121;
        final int dim = 2;
        double[][] x = new double[n][dim];
        double[] y = new double[n];
        int index = 0;
        for (int i = -10; i <= 10; i += 2) {
            for (int j = -10; j <= 10; j += 2) {
                x[index][0] = i;
                x[index][1] = j;
                y[index] = f.value(x[index]);
                ++index;
            }
        }

        MultivariateFunction p = interpolator.interpolate(x, y);

        double[] c = new double[dim];
        double expected, result;

        c[0] = 0;
        c[1] = 0;
        expected = f.value(c);
        result = p.value(c);
        Assert.assertEquals("On sample point", expected, result, FastMath.ulp(1d));

        c[0] = 2 + 1e-5;
        c[1] = 2 - 1e-5;
        expected = f.value(c);
        result = p.value(c);
        Assert.assertEquals("1e-5 away from sample point", expected, result, 1e-3);
    }
}