private BigFloat getCosineSunLocalHour(BigFloat sunTrueLong, Zenith zenith)
{
BigFloat sinSunDeclination = getSinOfSunDeclination(sunTrueLong);
BigFloat cosineSunDeclination = getCosineOfSunDeclination(sinSunDeclination);
BigFloat zenithInRads = convertDegreesToRadians(zenith.degrees());
BigFloat cosineZenith = BigFloat.valueOf(Math.Cos(zenithInRads.doubleValue()));
BigFloat sinLatitude = BigFloat.valueOf(Math.Sin(convertDegreesToRadians(location.getLatitude()).doubleValue()));
BigFloat cosLatitude = BigFloat.valueOf(Math.Cos(convertDegreesToRadians(location.getLatitude()).doubleValue()));
BigFloat sinDeclinationTimesSinLat = sinSunDeclination.Multiply(sinLatitude);
BigFloat dividend = cosineZenith.Subtract(sinDeclinationTimesSinLat);
BigFloat divisor = cosineSunDeclination.Multiply(cosLatitude);
return(setScale(divideBy(dividend, divisor)));
}
private BigFloat computeSolarEventTime(Zenith solarZenith, Calendar date, bool isSunrise)
{
date.setTimeZone(this.timeZone);
BigFloat longitudeHour = getLongitudeHour(date, isSunrise);
BigFloat meanAnomaly = getMeanAnomaly(longitudeHour);
BigFloat sunTrueLong = getSunTrueLongitude(meanAnomaly);
BigFloat cosineSunLocalHour = getCosineSunLocalHour(sunTrueLong, solarZenith);
if ((cosineSunLocalHour.doubleValue() < -1.0) || (cosineSunLocalHour.doubleValue() > 1.0))
{
return(null);
}
BigFloat sunLocalHour = getSunLocalHour(cosineSunLocalHour, isSunrise);
BigFloat localMeanTime = getLocalMeanTime(sunTrueLong, longitudeHour, sunLocalHour);
BigFloat localTime = getLocalTime(localMeanTime, date);
return(localTime);
}
/**
* Computes the sunrise time for the given zenith at the given date.
*
* @param solarZenith
* <code>Zenith</code> enum corresponding to the type of sunrise to compute.
* @param date
* <code>Calendar</code> object representing the date to compute the sunrise for.
* @return the sunrise time as a calendar or null for no sunrise
*/
public Calendar computeSunriseCalendar(Zenith solarZenith, Calendar date)
{
return(getLocalTimeAsCalendar(computeSolarEventTime(solarZenith, date, true), date));
}
/**
* Computes the sunrise time for the given zenith at the given date.
*
* @param solarZenith
* <code>Zenith</code> enum corresponding to the type of sunrise to compute.
* @param date
* <code>Calendar</code> object representing the date to compute the sunrise for.
* @return the sunrise time, in HH:MM format (24-hour clock), 00:00 if the sun does not rise on the given
* date.
*/
public String computeSunriseTime(Zenith solarZenith, Calendar date)
{
return(getLocalTimeAsString(computeSolarEventTime(solarZenith, date, true)));
}
