/// <summary>
/// Calculate prayer time for isha.
/// </summary>
private static double ComputeIshaTime(double jd, double ishaParameterValue, double latitude)
{
var dayFraction = AstronomyMath.GetDayFraction(IshaDefaultTime);
var ishaTime = AstronomyMath.ComputeSolarTime(jd, dayFraction, ishaParameterValue, latitude, Direction.Clockwise);
return(ishaTime);
}
/// <summary>
/// Calculate prayer time for maghrib.
/// </summary>
private static double ComputeMaghribTime(double jd, double maghribParameterValue, double latitude)
{
var dayFraction = AstronomyMath.GetDayFraction(MaghribDefaultTime);
var maghribTime = AstronomyMath.ComputeSolarTime(jd, dayFraction, maghribParameterValue, latitude, Direction.Clockwise);
return(maghribTime);
}
// /// <summary>
// /// Calculate prayer time for imsak.
// /// </summary>
// // NOTE: Do imsak time can be calculated using angle parameter?
// private static double ComputeImsakTime(double jd, double imsakParameterValue, double latitude)
// {
// var dayFraction = AstronomyMath.GetDayFraction(ImsakDefaultTime);
// var imsakTime = AstronomyMath.ComputeSolarTime(jd, dayFraction, imsakParameterValue, latitude, Direction.CounterClockwise);
//
// return imsakTime;
// }
/// <summary>
/// Calculate prayer time for fajr.
/// </summary>
private static double ComputeFajrTime(double jd, double fajrParameterValue, double latitude)
{
var dayFraction = AstronomyMath.GetDayFraction(FajrDefaultTime);
var fajrTime = AstronomyMath.ComputeSolarTime(jd, dayFraction, fajrParameterValue, latitude, Direction.CounterClockwise);
return(fajrTime);
}
/// <summary>
/// Calculate prayer time for sunset.
/// </summary>
private static double ComputeSunsetTime(double jd, double latitude, double altitude)
{
var dayFraction = AstronomyMath.GetDayFraction(SunsetDefaultTime);
var sunriseAngle = AstronomyMath.ComputeSunriseAngle(altitude);
var sunsetTime = AstronomyMath.ComputeSolarTime(jd, dayFraction, sunriseAngle, latitude, Direction.Clockwise);
return(sunsetTime);
}
/// <summary>
/// Calculate prayer time for asr.
/// </summary>
private static double ComputeAsrTime(double jd, int juristicTimeOfShadow, double latitude)
{
var dayFraction = AstronomyMath.GetDayFraction(AsrDefaultTime);
var sunDeclination = AstronomyMath.ComputeSunDeclination(jd + dayFraction);
var angle = -AngleMath.InverseCotangentInDegree(juristicTimeOfShadow + AngleMath.TangentOfDegree(Math.Abs(latitude - sunDeclination)));
var asrTime = AstronomyMath.ComputeSolarTime(jd, dayFraction, angle, latitude, Direction.Clockwise);
return(asrTime);
}
/// <summary>
/// Calculate prayer time for zuhr.
/// </summary>
private static double ComputeZuhrTime(double jd)
{
var dayFraction = AstronomyMath.GetDayFraction(ZuhrDefaultTime);
var midDay = AstronomyMath.ComputeMidDay(jd, dayFraction);
// The fiqh method which states that zuhr is when the sun's disk comes out
// of its zenith line, which is a line between the observer and the center
// of the sun when it is at the highest point is used here. Thus,
// additional 65 seconds is added to the mid day time, which corresponds
// to the formula t = arctan(r/d) / 2π × 24 × 60 × 60, where r is the
// radius of the sun (r = 695,000km), d is the sun-earth distance
// (d = 147,098,074km at minimum and d = 152,097,701km at maximum).
// When, d is at maximum, t evaluates to ~62 seconds and ~65 seconds when
// d is at minimum. Converting 65 seconds to hour yields a value of
// 0.018055555555555554.
var zuhrTime = midDay + 0.018055555555555554;
return(zuhrTime);
}
public void TestGetDayFractionForIshaDefaultTime()
{
Assert.Equal(0.75, AstronomyMath.GetDayFraction(18.0));
}
public void TestGetDayFractionForAsrDefaultTime()
{
Assert.Equal(0.5416666666666666, AstronomyMath.GetDayFraction(13.0));
}
public void TestGetDayFractionForZuhrDefaultTime()
{
Assert.Equal(0.5, AstronomyMath.GetDayFraction(12.0));
}
public void TestGetDayFractionForSunriseDefaultTime()
{
Assert.Equal(0.25, AstronomyMath.GetDayFraction(6.0));
}
public void TestGetDayFractionForFajrDefaultTime()
{
Assert.Equal(0.20833333333333334, AstronomyMath.GetDayFraction(5.0));
}
