FieldCellInterpolator.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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package org.orekit.models.earth.weather;
import java.util.function.Function;
import org.hipparchus.CalculusFieldElement;
import org.hipparchus.Field;
import org.hipparchus.analysis.interpolation.FieldBilinearInterpolatingFunction;
import org.hipparchus.util.MathArrays;
/** Interpolator within a grid cell.
* @param <T> type of the field elements
* @author Luc Maisonobe
* @since 12.1
*/
public class FieldCellInterpolator<T extends CalculusFieldElement<T>> {
/** Latitude of point of interest. */
private final T latitude;
/** Longitude of point of interest. */
private final T longitude;
/** South-West grid entry. */
private final FieldEvaluatedGridEntry<T> southWest;
/** South-East grid entry. */
private final FieldEvaluatedGridEntry<T> southEast;
/** North-West grid entry. */
private final FieldEvaluatedGridEntry<T> northWest;
/** North-East grid entry. */
private final FieldEvaluatedGridEntry<T> 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
*/
FieldCellInterpolator(final T latitude, final T longitude,
final FieldEvaluatedGridEntry<T> southWest, final FieldEvaluatedGridEntry<T> southEast,
final FieldEvaluatedGridEntry<T> northWest, final FieldEvaluatedGridEntry<T> 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
* @since 13.0
*/
T fieldInterpolate(final Function<FieldEvaluatedGridEntry<T>, T> gridGetter) {
final Field<T> field = latitude.getField();
final T zero = field.getZero();
// cell surrounding the point
final T[] xVal = MathArrays.buildArray(field, 2);
xVal[0] = zero.newInstance(southWest.getEntry().getLongitude());
xVal[1] = zero.newInstance(northEast.getEntry().getLongitude());
final T[] yVal = MathArrays.buildArray(field, 2);
yVal[0] = zero.newInstance(southWest.getEntry().getLatitude());
yVal[1] = zero.newInstance(northEast.getEntry().getLatitude());
// evaluate grid points at specified day
final T[][] fval = MathArrays.buildArray(field, 2, 2);
fval[0][0] = gridGetter.apply(southWest);
fval[0][1] = gridGetter.apply(northWest);
fval[1][0] = gridGetter.apply(southEast);
fval[1][1] = gridGetter.apply(northEast);
// perform interpolation in the grid
return new FieldBilinearInterpolatingFunction<>(xVal, yVal, fval).value(longitude, latitude);
}
}