ref: c00c60d327168c25e56077c8310cf2380833e9be
dir: /sys/src/cmd/astro/mars.c/
#include "astro.h"
void
mars(void)
{
double pturbl, pturbb, pturbr;
double lograd;
double dele, enom, vnom, nd, sl;
double lsun, elong, ci, dlong;
ecc = .09331290 + .000092064*capt;
incl = 1.850333 - 6.75e-4*capt;
node = 48.786442 + .770992*capt;
argp = 334.218203 + 1.840758*capt + 1.30e-4*capt2;
mrad = 1.5236915;
anom = 319.529425 + .5240207666*eday + 1.808e-4*capt2;
motion = 0.5240711638;
incl = incl*radian;
node = node*radian;
argp = argp*radian;
anom = fmod(anom,360.)*radian;
enom = anom + ecc*sin(anom);
do {
dele = (anom - enom + ecc * sin(enom)) /
(1. - ecc*cos(enom));
enom += dele;
} while(fabs(dele) > converge);
vnom = 2.*atan2(sqrt((1.+ecc)/(1.-ecc))*sin(enom/2.),cos(enom/2.));
rad = mrad*(1. - ecc*cos(enom));
lambda = vnom + argp;
pturbl = 0.;
lambda = lambda + pturbl*radsec;
pturbb = 0.;
pturbr = 0.;
/*
* reduce to the ecliptic
*/
nd = lambda - node;
lambda = node + atan2(sin(nd)*cos(incl),cos(nd));
sl = sin(incl)*sin(nd) + pturbb*radsec;
beta = atan2(sl, pyth(sl));
lograd = pturbr*2.30258509;
rad *= 1. + lograd;
motion *= radian*mrad*mrad/(rad*rad);
semi = 4.68;
lsun = 99.696678 + 0.9856473354*eday;
lsun *= radian;
elong = lambda - lsun;
ci = (rad - cos(elong))/sqrt(1. + rad*rad - 2.*rad*cos(elong));
dlong = atan2(pyth(ci), ci)/radian;
mag = -1.30 + .01486*dlong;
helio();
geo();
}