ucar.unidata.util.GaussianLatitudes Maven / Gradle / Ivy
/*
* Copyright 1998-2014 University Corporation for Atmospheric Research/Unidata
*
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* University Corporation for Atmospheric Research.
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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 - 2025 Weber Informatics LLC | Privacy Policy