LinearInterpolator.java

/*
 * Copyright (C) 2023 Alberto Irurueta Carro (alberto@irurueta.com)
 *
 * 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 com.irurueta.numerical.interpolation;

/**
 * Computes linear interpolation.
 */
public class LinearInterpolator extends BaseInterpolator {

    /**
     * Length of x's and y's to take into account.
     */
    private static final int M = 2;

    public LinearInterpolator(final double[] x, final double[] y) {
        super(x, y, M);
    }

    /**
     * Actual interpolation method to be implemented by subclasses.
     *
     * @param j index where value x to be interpolated in located in the array of xx.
     * @param x value to obtain interpolation for.
     * @return interpolated value.
     */
    @Override
    public double rawinterp(int j, double x) {
        if (xx[j] == xx[j + 1]) {
            return yy[j];
        } else {
            return yy[j] + ((x - xx[j]) / (xx[j + 1] - xx[j])) * (yy[j + 1] - yy[j]);
        }
    }
}