ucar.unidata.util.GaussianLatitudes Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of cdm Show documentation
The NetCDF-Java Library is a Java interface to NetCDF files, as well as to many other types of scientific data formats.
The newest version!
/*
 * Copyright 1998-2014 University Corporation for Atmospheric Research/Unidata
 *
 *   Portions of this software were developed by the Unidata Program at the
 *   University Corporation for Atmospheric Research.
 *
 *   Access and use of this software shall impose the following obligations
 *   and understandings on the user. The user is granted the right, without
 *   any fee or cost, to use, copy, modify, alter, enhance and distribute
 *   this software, and any derivative works thereof, and its supporting
 *   documentation for any purpose whatsoever, provided that this entire
 *   notice appears in all copies of the software, derivative works and
 *   supporting documentation.  Further, UCAR requests that the user credit
 *   UCAR/Unidata in any publications that result from the use of this
 *   software or in any product that includes this software. The names UCAR
 *   and/or Unidata, however, may not be used in any advertising or publicity
 *   to endorse or promote any products or commercial entity unless specific
 *   written permission is obtained from UCAR/Unidata. The user also
 *   understands that UCAR/Unidata is not obligated to provide the user with
 *   any support, consulting, training or assistance of any kind with regard
 *   to the use, operation and performance of this software nor to provide
 *   the user with any updates, revisions, new versions or "bug fixes."
 *
 *   THIS SOFTWARE IS PROVIDED BY UCAR/UNIDATA "AS IS" AND ANY EXPRESS OR
 *   IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 *   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *   DISCLAIMED. IN NO EVENT SHALL UCAR/UNIDATA BE LIABLE FOR ANY SPECIAL,
 *   INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
 *   FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
 *   NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
 *   WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE.
 */

package ucar.unidata.util;

/**
 * Calculate Gaussian Latitudes by finding the roots of the ordinary Legendre polynomial of degree
 * NLAT using Newton's iteration method.
 *
 * @author caron port to Java
 * @author Amy Solomon, 28 Jan 1991, via http://dss.ucar.edu/libraries/gridinterps/gaus-lats.f
 */
public class GaussianLatitudes {
  private static final double XLIM  = 1.0E-7;

  // all these have size nlat
  public double[] cosc; // cos(colatitude) or sin(latitude)
  public double[] colat; // the colatitudes in radians
  public double[] gaussw; // the Gaussian weights
  public double[] latd; // the latitudes in degrees
  public double[] sinc; // sin(colatitude) or cos(latitude)
  public double[] wos2; // Gaussian weight over sin**2(colatitude)

  /**
   * Constructor
   * @param nlat the total number of latitudes from pole to pole (degree of the polynomial)
   */
  public GaussianLatitudes(int nlat) {
    if (nlat == 0) throw new IllegalArgumentException("nlats may not be zero");

    // the number of latitudes between pole and equator
    int  nzero = nlat/2;
    cosc = new double[nlat];
    colat = new double[nlat];
    gaussw = new double[nlat];
    latd = new double[nlat];
    sinc = new double[nlat];
    wos2 = new double[nlat];

    /* set first guess for cos(colat)
      PI = 3.141592653589793
      DO 10 I=1,NZERO
         COSC(I) = SIN( (I-0.5)*PI/NLAT + PI*0.5 )
   10 CONTINUE */
    for (int i=0; i© 2015 - 2024 Weber Informatics LLC | Privacy Policy