1   /* Copyright 2022-2025 Thales Alenia Space
2    * Licensed to CS Communication & Systèmes (CS) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * CS licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *   http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.orekit.models.earth.weather.water;
18  
19  import org.hipparchus.CalculusFieldElement;
20  import org.hipparchus.analysis.polynomials.PolynomialFunction;
21  import org.hipparchus.util.FastMath;
22  import org.orekit.models.earth.troposphere.TroposphericModelUtils;
23  
24  /** Conversion polynomial from "The Principle of the GPS Precise Positioning System", Wang et al, 1988.
25   * <p>
26   * This corresponds to equation 5.96 in Guochang Xu, GPS - Theory, Algorithms and Applications, Springer, 2007.
27   * </p>
28   * @author Luc Maisonobe
29   * @since 12.1
30   */
31  public class Wang1988 implements WaterVaporPressureProvider {
32  
33      /** Coefficients for the partial pressure of water vapor polynomial. */
34      private static final double[] E_COEFFICIENTS = {
35          -37.2465, 0.213166, -0.000256908
36      };
37  
38      /** Conversion polynomial. */
39      private static final PolynomialFunction E_POLYNOMIAL = new PolynomialFunction(E_COEFFICIENTS);
40  
41      /** {@inheritDoc} */
42      @Override
43      public double waterVaporPressure(final double p, final double t, final double rh) {
44          return TroposphericModelUtils.HECTO_PASCAL.toSI(rh * FastMath.exp(E_POLYNOMIAL.value(t)));
45      }
46  
47      /** {@inheritDoc} */
48      @Override
49      public <T extends CalculusFieldElement<T>> T waterVaporPressure(final T p, final T t, final T rh) {
50          return TroposphericModelUtils.HECTO_PASCAL.toSI(rh.multiply(FastMath.exp(E_POLYNOMIAL.value(t))));
51      }
52  
53  }