void SkyPoint::nutate(const KSNumbers *num) {
double cosRA, sinRA, cosDec, sinDec, tanDec;
double cosOb, sinOb;
RA.SinCos( sinRA, cosRA );
Dec.SinCos( sinDec, cosDec );
num->obliquity()->SinCos( sinOb, cosOb );
//Step 2: Nutation
if ( fabs( Dec.Degrees() ) < 80.0 ) { //approximate method
tanDec = sinDec/cosDec;
double dRA = num->dEcLong()*( cosOb + sinOb*sinRA*tanDec ) - num->dObliq()*cosRA*tanDec;
double dDec = num->dEcLong()*( sinOb*cosRA ) + num->dObliq()*sinRA;
RA.setD( RA.Degrees() + dRA );
Dec.setD( Dec.Degrees() + dDec );
} else { //exact method
dms EcLong, EcLat;
findEcliptic( num->obliquity(), EcLong, EcLat );
//Add dEcLong to the Ecliptic Longitude
dms newLong( EcLong.Degrees() + num->dEcLong() );
setFromEcliptic( num->obliquity(), newLong, EcLat );
}
}
void KSPlanetBase::EclipticToEquatorial( const dms *Obliquity ) {
setFromEcliptic( Obliquity, &ep.longitude, &ep.latitude );
}
