/* * Apache License * Version 2.0, January 2004 * http://www.apache.org/licenses/ * * Copyright 2013 Aurelian Tutuianu * Copyright 2014 Aurelian Tutuianu * Copyright 2015 Aurelian Tutuianu * Copyright 2016 Aurelian Tutuianu * * Licensed 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 rapaio.core.distributions.empirical; /** * Epanechnikov kernel function * User: <a href="mailto:padreati@yahoo.com">Aurelian Tutuianu</a> */ public class KFuncEpanechnikov implements KFunc { private static final long serialVersionUID = 8568853478296387174L; @Override public double pdf(double x, double x0, double bandwidth) { double value = Math.abs(x - x0) / bandwidth; return value <= 1 ? 3. * (1 - value * value) / 4. : 0; } @Override public double minValue(double x0, double bandwidth) { return x0 - bandwidth; } @Override public double getMaxValue(double x0, double bandwidth) { return x0 + bandwidth; } @Override public String summary() { return "KFuncEpanechnikov"; } }