CellInterpolator.java
/* Copyright 2002-2024 Thales Alenia Space
* Licensed to CS GROUP (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS 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,
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* See the License for the specific language governing permissions and
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*/
package org.orekit.models.earth.weather;
import java.util.function.ToDoubleFunction;
import org.hipparchus.analysis.interpolation.BilinearInterpolatingFunction;
/** Interpolator within a grid cell.
* @author Luc Maisonobe
* @since 12.1
*/
public class CellInterpolator {
/** Latitude of point of interest. */
private final double latitude;
/** Longitude of point of interest. */
private final double longitude;
/** South-West grid entry. */
private final GridEntry southWest;
/** South-East grid entry. */
private final GridEntry southEast;
/** North-West grid entry. */
private final GridEntry northWest;
/** North-East grid entry. */
private final GridEntry northEast;
/** Simple constructor.
* @param latitude latitude of point of interest
* @param longitude longitude of point of interest
* @param southWest South-West grid entry
* @param southEast South-East grid entry
* @param northWest North-West grid entry
* @param northEast North-East grid entry
*/
CellInterpolator(final double latitude, final double longitude,
final GridEntry southWest, final GridEntry southEast,
final GridEntry northWest, final GridEntry northEast) {
this.latitude = latitude;
this.longitude = longitude;
this.southWest = southWest;
this.southEast = southEast;
this.northWest = northWest;
this.northEast = northEast;
}
/** Interpolate a grid function.
* @param gridGetter getter for the grid function
* @return interpolated function"
*/
double interpolate(final ToDoubleFunction<GridEntry> gridGetter) {
// cell surrounding the point
final double[] xVal = new double[] {
southWest.getLongitude(), southEast.getLongitude()
};
final double[] yVal = new double[] {
southWest.getLatitude(), northWest.getLatitude()
};
// evaluate grid points at specified day
final double[][] fval = new double[][] {
{
gridGetter.applyAsDouble(southWest),
gridGetter.applyAsDouble(northWest)
}, {
gridGetter.applyAsDouble(southEast),
gridGetter.applyAsDouble(northEast)
}
};
// perform interpolation in the grid
return new BilinearInterpolatingFunction(xVal, yVal, fval).value(longitude, latitude);
}
}