source: Sophya/trunk/SophyaExt/XephemAstroLib/moonnf.c@ 2996

#include <stdio.h>
#include <math.h>

#include "astro.h"

static void m (double t, double k, double *mj);

#define unw(w,z)        ((w)-floor((w)/(z))*(z))

/* given a modified Julian date, mj, return the mjd of the new
 * and full moons about then, mjn and mjf.
 * TODO: exactly which ones does it find? eg:
 *   5/28/1988 yields 5/15 and 5/31
 *   5/29             6/14     6/29
 */
void
moonnf (double mj, double *mjn, double *mjf)
{
        int mo, yr;
        double dy;
        double mj0;
        double k, tn, tf, t;

        mjd_cal (mj, &mo, &dy, &yr);
        cal_mjd (1, 0., yr, &mj0);
        k = (yr-1900+((mj-mj0)/365))*12.3685;
        k = floor(k+0.5);
        tn = k/1236.85;
        tf = (k+0.5)/1236.85;
        t = tn;
        m (t, k, mjn);
        t = tf;
        k += 0.5;
        m (t, k, mjf);
}

static void
m (double t, double k, double *mj)
{
        double t2, a, a1, b, b1, c, ms, mm, f, ddjd;

        t2 = t*t;
        a = 29.53*k;
        c = degrad(166.56+(132.87-9.173e-3*t)*t);
        b = 5.8868e-4*k+(1.178e-4-1.55e-7*t)*t2+3.3e-4*sin(c)+7.5933E-1;
        ms = 359.2242+360*unw(k/1.236886e1,1)-(3.33e-5+3.47e-6*t)*t2;
        mm = 306.0253+360*unw(k/9.330851e-1,1)+(1.07306e-2+1.236e-5*t)*t2;
        f = 21.2964+360*unw(k/9.214926e-1,1)-(1.6528e-3+2.39e-6*t)*t2;
        ms = unw(ms,360);
        mm = unw(mm,360);
        f = unw(f,360);
        ms = degrad(ms);
        mm = degrad(mm);
        f = degrad(f);
        ddjd = (1.734e-1-3.93e-4*t)*sin(ms)+2.1e-3*sin(2*ms)
                -4.068e-1*sin(mm)+1.61e-2*sin(2*mm)-4e-4*sin(3*mm)
                +1.04e-2*sin(2*f)-5.1e-3*sin(ms+mm)-7.4e-3*sin(ms-mm)
                +4e-4*sin(2*f+ms)-4e-4*sin(2*f-ms)-6e-4*sin(2*f+mm)
                +1e-3*sin(2*f-mm)+5e-4*sin(ms+2*mm);
        a1 = (long)a;
        b = b+ddjd+(a-a1);
        b1 = (long)b;
        a = a1+b1;
        b = b-b1;
        *mj = a + b;
}

/* For RCS Only -- Do Not Edit */
static char *rcsid[2] = {(char *)rcsid, "@(#) $RCSfile: moonnf.c,v $ $Date: 2005-08-21 10:02:38 $ $Revision: 1.3 $ $Name: not supported by cvs2svn $"};