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bdastrocalc's Issues

Swift 4.x Update?

Any chance this can be updated for Swift 4.x?

Thanks!

SPM support

Hi,
can you add support for swift package manager?

thank

Moon tilt

Hi,
i've write this function for calculate the moon tilt illusion angle, according to this document: http://master.grad.hr/hdgg/kog_stranica/kog18/06myers-KoG18.pdf

static func moonTilt (date: NSDate, location: CLLocationCoordinate2D) -> (alfa: Double, beta: Double, diff: Double) {      

        let moonAltitude = moonPosition(date: date, location: location).altitude
        let moonAzimuth = moonPosition(date: date, location: location).azimuth
        let sunAltitude = sunPosition(date: date, location: location).altitude
        let sunAzimuth = sunPosition(date: date, location: location).azimuth

        let absAzimMoonSun = abs(sunAzimuth - moonAzimuth)
        let tanAlfa = ((cos(moonAltitude) * tan(sunAltitude)) - (sin(moonAltitude) * cos(absAzimMoonSun))) / sin(absAzimMoonSun)
        let tanBeta = (sin(moonAltitude) - sin(sunAltitude)) / (cos(sunAltitude) * sin(absAzimMoonSun))
        var diff = 0.0
        if (absAzimMoonSun * radiansToDegrees) <= 180 {
            diff = atan(-tanBeta)
        } else {
            diff = atan(tanAlfa)
        }

        return (tanAlfa, -tanBeta, diff)
    }

I use this code to rotate an image of the moon, but it presents a constant error when compared to sites like: https://www.timeanddate.com/astronomy/italy/turin
or
https://www.mooncalc.org/#/45.3502,7.744,13/2018.09.05/09:26/99/0

Can someone tell me what's wrong?