' Calculation of local times of sunrise, solar noon, and sunset
' based on the calculation procedure by NOAA in the javascript in
' http://www.srrb.noaa.gov/highlights/sunrise/sunrise.html and
' http://www.srrb.noaa.gov/highlights/sunrise/azel.html
'
' Five functions are available for use from Excel worksheets:
'
' - sunrise(lat, lon, year, month, day, timezone, dlstime)
' - solarnoon(lat, lon, year, month, day, timezone, dlstime)
' - sunset(lat, lon, year, month, day, timezone, dlstime)
' - solarazimuth(lat, lon, year, month, day, hour, minute, second, timezone, dlstime)
' - solarelevation(lat, lon, year, month, day, hour, minute, second, timezone, dlstime)
'
' The sign convention for inputs to the functions named sunrise, solarnoon,
' sunset, solarazimuth, and solarelevationis:
'
' - positive latitude decimal degrees for northern hemisphere
' - negative longitude degrees for western hemisphere
' - negative time zone hours for western hemisphere
'
' The other functions in the VBA module use the original
' NOAA sign convention of positive longitude in the western hemisphere.
'
' The calculations in the NOAA Sunrise/Sunset and Solar Position
' Calculators are based on equations from Astronomical Algorithms,
' by Jean Meeus. NOAA also included atmospheric refraction effects.
' The sunrise and sunset results were reported by NOAA
' to be accurate to within +/- 1 minute for locations between +/- 72°
' latitude, and within ten minutes outside of those latitudes.
'
' This translation was tested for selected locations
' and found to provide results within +/- 1 minute of the
' original Javascript code.
'
' This translation does not include calculation of prior or next
' susets for locations above the Arctic Circle and below the
' Antarctic Circle, when a sunrise or sunset does not occur.
'
' Translated from NOAA's Javascript to Excel VBA by:
'
' Greg Pelletier
' Department of Ecology
' P.O.Box 47600
' Olympia, WA 98504-7600
' email: gpel461@ ecy.wa.gov
Option Explicit
Function radToDeg(angleRad)
'// Convert radian angle to degrees
radToDeg = (180# * angleRad / Pi)
End Function
Function degToRad(angleDeg)
'// Convert degree angle to radians
degToRad = (Pi * angleDeg / 180#)
End Function
Function calcJD(year, month, day)
'***********************************************************************/
'* Name: calcJD
'* Type: Function
'* Purpose: Julian day from calendar day
'* Arguments:
'* year : 4 digit year
'* month: January = 1
'* day : 1 - 31
'* Return value:
'* The Julian day corresponding to the date
'* Note:
'* Number is returned for start of day. Fractional days should be
'* added later.
'***********************************************************************/
Dim A As Double, B As Double, JD As Double
If (month <= 2) Then
year = year - 1
month = month + 12
End If
A = Floor(year / 100, 1)
B = 2 - A + Floor(A / 4, 1)
JD = Floor(365.25 * (year + 4716), 1) + _
Floor(30.6001 * (month + 1), 1) + day + B - 1524.5
calcJD = JD
'gp put the year and month back where they belong
If month = 13 Then
month = 1
year = year + 1
End If
If month = 14 Then
month = 2
year = year + 1
End If
End Function
Function calcTimeJulianCent(JD)
'***********************************************************************/
'* Name: calcTimeJulianCent
'* Type: Function
'* Purpose: convert Julian Day to centuries since J2000.0.
'* Arguments:
'* jd : the Julian Day to convert
'* Return value:
'* the T value corresponding to the Julian Day
'***********************************************************************/
Dim t As Double
t = (JD - 2451545#) / 36525#
calcTimeJulianCent = t
End Function
Function calcJDFromJulianCent(t)
'***********************************************************************/
'* Name: calcJDFromJulianCent
'* Type: Function
'* Purpose: convert centuries since J2000.0 to Julian Day.
'* Arguments:
'* t : number of Julian centuries since J2000.0
'* Return value:
'* the Julian Day corresponding to the t value
'***********************************************************************/
Dim JD As Double
JD = t * 36525# + 2451545#
calcJDFromJulianCent = JD
End Function
Function calcGeomMeanLongSun(t)
'***********************************************************************/
'* Name: calGeomMeanLongSun
'* Type: Function
'* Purpose: calculate the Geometric Mean Longitude of the Sun
'* Arguments:
'* t : number of Julian centuries since J2000.0
'* Return value:
'* the Geometric Mean Longitude of the Sun in degrees
'***********************************************************************/
Dim l0 As Double
l0 = 280.46646 + t * (36000.76983 + 0.0003032 * t)
Do
If (l0 <= 360) And (l0 >= 0) Then Exit Do
If l0 > 360 Then l0 = l0 - 360
If l0 < 0 Then l0 = l0 + 360
Loop
calcGeomMeanLongSun = l0
End Function
Function calcGeomMeanAnomalySun(t)
'***********************************************************************/
'* Name: calGeomAnomalySun
'* Type: Function
'* Purpose: calculate the Geometric Mean Anomaly of the Sun
'* Arguments:
'* t : number of Julian centuries since J2000.0
'* Return value:
'* the Geometric Mean Anomaly of the Sun in degrees
'***********************************************************************/
Dim m As Double
m = 357.52911 + t * (35999.05029 - 0.0001537 * t)
calcGeomMeanAnomalySun = m
End Function
Function calcEccentricityEarthOrbit(t)
'***********************************************************************/
'* Name: calcEccentricityEarthOrbit
'* Type: Function
'* Purpose: calculate the eccentricity of earth's orbit
'* Arguments:
'* t : number of Julian centuries since J2000.0
'* Return value:
'* the unitless eccentricity
'***********************************************************************/
Dim e As Double
e = 0.016708634 - t * (0.000042037 + 0.0000001267 * t)
calcEccentricityEarthOrbit = e
End Function
Function calcSunEqOfCenter(t)
'***********************************************************************/
'* Name: calcSunEqOfCenter
'* Type: Function
'* Purpose: calculate the equation of center for the sun
'* Arguments:
'* t : number of Julian centuries since J2000.0
'* Return value:
'* in degrees
'***********************************************************************/
Dim m As Double, mrad As Double, sinm As Double, sin2m As Double, sin3m As Double
Dim c As Double
m = calcGeomMeanAnomalySun(t)
mrad = degToRad(m)
sinm = Sin(mrad)
sin2m = Sin(mrad + mrad)
sin3m = Sin(mrad + mrad + mrad)
c = sinm * (1.914602 - t * (0.004817 + 0.000014 * t)) _
+ sin2m * (0.019993 - 0.000101 * t) + sin3m * 0.000289
calcSunEqOfCenter = c
End Function
Function calcSunTrueLong(t)
'***********************************************************************/
'* Name: calcSunTrueLong
'* Type: Function
'* Purpose: calculate the true longitude of the sun
'* Arguments:
'* t : number of Julian centuries since J2000.0
'* Return value:
'* sun's true longitude in degrees
'***********************************************************************/
Dim l0 As Double, c As Double, O As Double
l0 = calcGeomMeanLongSun(t)
c = calcSunEqOfCenter(t)
O = l0 + c
calcSunTrueLong = O
End Function
Function calcSunTrueAnomaly(t)
'***********************************************************************/
'* Name: calcSunTrueAnomaly (not used by sunrise, solarnoon, sunset)
'* Type: Function
'* Purpose: calculate the true anamoly of the sun
'* Arguments:
'* t : number of Julian centuries since J2000.0
'* Return value:
'* sun's true anamoly in degrees
'***********************************************************************/
Dim m As Double, c As Double, v As Double
m = calcGeomMeanAnomalySun(t)
c = calcSunEqOfCenter(t)
v = m + c
calcSunTrueAnomaly = v
End Function
Function calcSunRadVector(t)
'***********************************************************************/
'* Name: calcSunRadVector (not used by sunrise, solarnoon, sunset)
'* Type: Function
'* Purpose: calculate the distance to the sun in AU
'* Arguments:
'* t : number of Julian centuries since J2000.0
'* Return value:
'* sun radius vector in AUs
'***********************************************************************/
Dim v As Double, e As Double, R As Double
v = calcSunTrueAnomaly(t)
e = calcEccentricityEarthOrbit(t)
R = (1.000001018 * (1 - e * e)) / (1 + e * Cos(degToRad(v)))
calcSunRadVector = R
End Function
Function calcSunApparentLong(t)
'***********************************************************************/
'* Name: calcSunApparentLong (not used by sunrise, solarnoon, sunset)
'* Type: Function
'* Purpose: calculate the apparent longitude of the sun
'* Arguments:
'* t : number of Julian centuries since J2000.0
'* Return value:
'* sun's apparent longitude in degrees
'***********************************************************************/
Dim O As Double, omega As Double, lambda As Double
O = calcSunTrueLong(t)
omega = 125.04 - 1934.136 * t
lambda = O - 0.00569 - 0.00478 * Sin(degToRad(omega))
calcSunApparentLong = lambda
End Function
Function calcMeanObliquityOfEcliptic(t)
'***********************************************************************/
'* Name: calcMeanObliquityOfEcliptic
'* Type: Function
'* Purpose: calculate the mean obliquity of the ecliptic
'* Arguments:
'* t : number of Julian centuries since J2000.0
'* Return value:
'* mean obliquity in degrees
'***********************************************************************/
Dim seconds As Double, e0 As Double
seconds = 21.448 - t * (46.815 + t * (0.00059 - t * (0.001813)))
e0 = 23# + (26# + (seconds / 60#)) / 60#
calcMeanObliquityOfEcliptic = e0
End Function
Function calcObliquityCorrection(t)
'***********************************************************************/
'* Name: calcObliquityCorrection
'* Type: Function
'* Purpose: calculate the corrected obliquity of the ecliptic
'* Arguments:
'* t : number of Julian centuries since J2000.0
'* Return value:
'* corrected obliquity in degrees
'***********************************************************************/
Dim e0 As Double, omega As Double, e As Double
e0 = calcMeanObliquityOfEcliptic(t)
omega = 125.04 - 1934.136 * t
e = e0 + 0.00256 * Cos(degToRad(omega))
calcObliquityCorrection = e
End Function
Function calcSunRtAscension(t)
'***********************************************************************/
'* Name: calcSunRtAscension (not used by sunrise, solarnoon, sunset)
'* Type: Function
'* Purpose: calculate the right ascension of the sun
'* Arguments:
'* t : number of Julian centuries since J2000.0
'* Return value:
'* sun's right ascension in degrees
'***********************************************************************/
Dim e As Double, lambda As Double, tananum As Double, tanadenom As Double
Dim alpha As Double
e = calcObliquityCorrection(t)
lambda = calcSunApparentLong(t)
tananum = (Cos(degToRad(e)) * Sin(degToRad(lambda)))
tanadenom = (Cos(degToRad(lambda)))
'original NOAA code using javascript Math.Atan2(y,x) convention:
' var alpha = radToDeg(Math.atan2(tananum, tanadenom));
' alpha = radToDeg(Application.WorksheetFunction.Atan2(tananum, tanadenom))
'translated using Excel VBA Application.WorksheetFunction.Atan2(x,y) convention:
alpha = radToDeg(Atan2(tanadenom, tananum))
calcSunRtAscension = alpha
End Function
Function calcSunDeclination(t)
'***********************************************************************/
'* Name: calcSunDeclination
'* Type: Function
'* Purpose: calculate the declination of the sun
'* Arguments:
'* t : number of Julian centuries since J2000.0
'* Return value:
'* sun's declination in degrees
'***********************************************************************/
Dim e As Double, lambda As Double, sint As Double, theta As Double
e = calcObliquityCorrection(t)
lambda = calcSunApparentLong(t)
sint = Sin(degToRad(e)) * Sin(degToRad(lambda))
theta = radToDeg(Asin(sint))
calcSunDeclination = theta
End Function
Function calcEquationOfTime(t)
'***********************************************************************/
'* Name: calcEquationOfTime
'* Type: Function
'* Purpose: calculate the difference between true solar time and mean
'* solar time
'* Arguments:
'* t : number of Julian centuries since J2000.0
'* Return value:
'* equation of time in minutes of time
'***********************************************************************/
Dim epsilon As Double, l0 As Double, e As Double, m As Double
Dim Y As Double, sin2l0 As Double, sinm As Double
Dim cos2l0 As Double, sin4l0 As Double, sin2m As Double, Etime As Double
epsilon = calcObliquityCorrection(t)
l0 = calcGeomMeanLongSun(t)
e = calcEccentricityEarthOrbit(t)
m = calcGeomMeanAnomalySun(t)
Y = Tan(degToRad(epsilon) / 2#)
Y = Y ^ 2
sin2l0 = Sin(2# * degToRad(l0))
sinm = Sin(degToRad(m))
cos2l0 = Cos(2# * degToRad(l0))
sin4l0 = Sin(4# * degToRad(l0))
sin2m = Sin(2# * degToRad(m))
Etime = Y * sin2l0 - 2# * e * sinm + 4# * e * Y * sinm * cos2l0 _
- 0.5 * Y * Y * sin4l0 - 1.25 * e * e * sin2m
calcEquationOfTime = radToDeg(Etime) * 4#
End Function
Function calcHourAngleDawn(lat, solarDec, solardepression)
'***********************************************************************/
'* Name: calcHourAngleDawn
'* Type: Function
'* Purpose: calculate the hour angle of the sun at dawn for the
'* latitude
'* for user selected solar depression below horizon
'* Arguments:
'* lat : latitude of observer in degrees
'* solarDec : declination angle of sun in degrees
'* solardepression: angle of the sun below the horizion in degrees
'* Return value:
'* hour angle of dawn in radians
'***********************************************************************/
Dim latRad As Double, sdRad As Double, HAarg As Double, HA As Double
latRad = degToRad(lat)
sdRad = degToRad(solarDec)
HAarg = (Cos(degToRad(90 + solardepression)) / (Cos(latRad) * Cos(sdRad)) - Tan(latRad) * Tan(sdRad))
HA = (Acos(Cos(degToRad(90 + solardepression)) _
/ (Cos(latRad) * Cos(sdRad)) - Tan(latRad) * Tan(sdRad)))
calcHourAngleDawn = HA
End Function
Function calcHourAngleSunrise(lat, solarDec)
'***********************************************************************/
'* Name: calcHourAngleSunrise
'* Type: Function
'* Purpose: calculate the hour angle of the sun at sunrise for the
'* latitude
'* Arguments:
'* lat : latitude of observer in degrees
'* solarDec : declination angle of sun in degrees
'* Return value:
'* hour angle of sunrise in radians
'*
'* Note: For sunrise and sunset calculations, we assume 0.833° of atmospheric refraction
'* For details about refraction see http://www.srrb.noaa.gov/highlights/sunrise/calcdetails.html
'*
'***********************************************************************/
Dim latRad As Double, sdRad As Double, HAarg As Double, HA As Double
latRad = degToRad(lat)
sdRad = degToRad(solarDec)
HAarg = (Cos(degToRad(90.833)) / (Cos(latRad) * Cos(sdRad)) - Tan(latRad) * Tan(sdRad))
HA = (Acos(Cos(degToRad(90.833)) _
/ (Cos(latRad) * Cos(sdRad)) - Tan(latRad) * Tan(sdRad)))
calcHourAngleSunrise = HA
End Function
Function calcHourAngleSunset(lat, solarDec)
'***********************************************************************/
'* Name: calcHourAngleSunset
'* Type: Function
'* Purpose: calculate the hour angle of the sun at sunset for the
'* latitude
'* Arguments:
'* lat : latitude of observer in degrees
'* solarDec : declination angle of sun in degrees
'* Return value:
'* hour angle of sunset in radians
'*
'* Note: For sunrise and sunset calculations, we assume 0.833° of atmospheric refraction
'* For details about refraction see http://www.srrb.noaa.gov/highlights/sunrise/calcdetails.html
'*
'***********************************************************************/
Dim latRad As Double, sdRad As Double, HAarg As Double, HA As Double
latRad = degToRad(lat)
sdRad = degToRad(solarDec)
HAarg = (Cos(degToRad(90.833)) / (Cos(latRad) * Cos(sdRad)) - Tan(latRad) * Tan(sdRad))
HA = (Acos(Cos(degToRad(90.833)) _
/ (Cos(latRad) * Cos(sdRad)) - Tan(latRad) * Tan(sdRad)))
calcHourAngleSunset = -HA
End Function
Function calcHourAngleDusk(lat, solarDec, solardepression)
'***********************************************************************/
'* Name: calcHourAngleDusk
'* Type: Function
'* Purpose: calculate the hour angle of the sun at dusk for the
'* latitude
'* for user selected solar depression below horizon
'* Arguments:
'* lat : latitude of observer in degrees
'* solarDec : declination angle of sun in degrees
'* solardepression: angle of sun below horizon in degrees
'* Return value:
'* hour angle of dusk in radians
'***********************************************************************/
Dim latRad As Double, sdRad As Double, HAarg As Double, HA As Double
latRad = degToRad(lat)
sdRad = degToRad(solarDec)
HAarg = (Cos(degToRad(90 + solardepression)) / (Cos(latRad) * Cos(sdRad)) - Tan(latRad) * Tan(sdRad))
HA = (Acos(Cos(degToRad(90 + solardepression)) _
/ (Cos(latRad) * Cos(sdRad)) - Tan(latRad) * Tan(sdRad)))
calcHourAngleDusk = -HA
End Function
Function calcDawnUTC(JD, latitude, longitude, solardepression)
'***********************************************************************/
'* Name: calcDawnUTC
'* Type: Function
'* Purpose: calculate the Universal Coordinated Time (UTC) of dawn
'* for the given day at the given location on earth
'* for user selected solar depression below horizon
'* Arguments:
'* JD : julian day
'* latitude : latitude of observer in degrees
'* longitude : longitude of observer in degrees
'* solardepression: angle of sun below the horizon in degrees
'* Return value:
'* time in minutes from zero Z
'***********************************************************************/
Dim t As Double, eqtime As Double, solarDec As Double, hourangle As Double
Dim delta As Double, timeDiff As Double, timeUTC As Double
Dim newt As Double
t = calcTimeJulianCent(JD)
' // *** First pass to approximate sunrise
eqtime = calcEquationOfTime(t)
solarDec = calcSunDeclination(t)
hourangle = calcHourAngleSunrise(latitude, solarDec)
delta = longitude - radToDeg(hourangle)
timeDiff = 4 * delta
' in minutes of time
timeUTC = 720 + timeDiff - eqtime
' in minutes
' *** Second pass includes fractional jday in gamma calc
newt = calcTimeJulianCent(calcJDFromJulianCent(t) + timeUTC / 1440#)
eqtime = calcEquationOfTime(newt)
solarDec = calcSunDeclination(newt)
hourangle = calcHourAngleDawn(latitude, solarDec, solardepression)
delta = longitude - radToDeg(hourangle)
timeDiff = 4 * delta
timeUTC = 720 + timeDiff - eqtime
' in minutes
calcDawnUTC = timeUTC
End Function
Function calcSunriseUTC(JD, latitude, longitude)
'***********************************************************************/
'* Name: calcSunriseUTC
'* Type: Function
'* Purpose: calculate the Universal Coordinated Time (UTC) of sunrise
'* for the given day at the given location on earth
'* Arguments:
'* JD : julian day
'* latitude : latitude of observer in degrees
'* longitude : longitude of observer in degrees
'* Return value:
'* time in minutes from zero Z
'***********************************************************************/
Dim t As Double, eqtime As Double, solarDec As Double, hourangle As Double
Dim delta As Double, timeDiff As Double, timeUTC As Double
Dim newt As Double
t = calcTimeJulianCent(JD)
' // *** First pass to approximate sunrise
eqtime = calcEquationOfTime(t)
solarDec = calcSunDeclination(t)
hourangle = calcHourAngleSunrise(latitude, solarDec)
delta = longitude - radToDeg(hourangle)
timeDiff = 4 * delta
' in minutes of time
timeUTC = 720 + timeDiff - eqtime
' in minutes
' *** Second pass includes fractional jday in gamma calc
newt = calcTimeJulianCent(calcJDFromJulianCent(t) + timeUTC / 1440#)
eqtime = calcEquationOfTime(newt)
solarDec = calcSunDeclination(newt)
hourangle = calcHourAngleSunrise(latitude, solarDec)
delta = longitude - radToDeg(hourangle)
timeDiff = 4 * delta
timeUTC = 720 + timeDiff - eqtime
' in minutes
calcSunriseUTC = timeUTC
End Function
Function calcSolNoonUTC(t, longitude)
'***********************************************************************/
'* Name: calcSolNoonUTC
'* Type: Function
'* Purpose: calculate the Universal Coordinated Time (UTC) of solar
'* noon for the given day at the given location on earth
'* Arguments:
'* t : number of Julian centuries since J2000.0
'* longitude : longitude of observer in degrees
'* Return value:
'* time in minutes from zero Z
'***********************************************************************/
Dim newt As Double, eqtime As Double, solarNoonDec As Double, solNoonUTC As Double
newt = calcTimeJulianCent(calcJDFromJulianCent(t) + 0.5 + longitude / 360#)
eqtime = calcEquationOfTime(newt)
solarNoonDec = calcSunDeclination(newt)
solNoonUTC = 720 + (longitude * 4) - eqtime
calcSolNoonUTC = solNoonUTC
End Function
Function calcSunsetUTC(JD, latitude, longitude)
'***********************************************************************/
'* Name: calcSunsetUTC
'* Type: Function
'* Purpose: calculate the Universal Coordinated Time (UTC) of sunset
'* for the given day at the given location on earth
'* Arguments:
'* JD : julian day
'* latitude : latitude of observer in degrees
'* longitude : longitude of observer in degrees
'* Return value:
'* time in minutes from zero Z
'***********************************************************************/
Dim t As Double, eqtime As Double, solarDec As Double, hourangle As Double
Dim delta As Double, timeDiff As Double, timeUTC As Double
Dim newt As Double
t = calcTimeJulianCent(JD)
' // First calculates sunrise and approx length of day
eqtime = calcEquationOfTime(t)
solarDec = calcSunDeclination(t)
hourangle = calcHourAngleSunset(latitude, solarDec)
delta = longitude - radToDeg(hourangle)
timeDiff = 4 * delta
timeUTC = 720 + timeDiff - eqtime
' // first pass used to include fractional day in gamma calc
newt = calcTimeJulianCent(calcJDFromJulianCent(t) + timeUTC / 1440#)
eqtime = calcEquationOfTime(newt)
solarDec = calcSunDeclination(newt)
hourangle = calcHourAngleSunset(latitude, solarDec)
delta = longitude - radToDeg(hourangle)
timeDiff = 4 * delta
timeUTC = 720 + timeDiff - eqtime
' // in minutes
calcSunsetUTC = timeUTC
End Function
Function calcDuskUTC(JD, latitude, longitude, solardepression)
'***********************************************************************/
'* Name: calcDuskUTC
'* Type: Function
'* Purpose: calculate the Universal Coordinated Time (UTC) of dusk
'* for the given day at the given location on earth
'* for user selected solar depression below horizon
'* Arguments:
'* JD : julian day
'* latitude : latitude of observer in degrees
'* longitude : longitude of observer in degrees
'* solardepression: angle of sun below horizon
'* Return value:
'* time in minutes from zero Z
'***********************************************************************/
Dim t As Double, eqtime As Double, solarDec As Double, hourangle As Double
Dim delta As Double, timeDiff As Double, timeUTC As Double
Dim newt As Double
t = calcTimeJulianCent(JD)
' // First calculates sunrise and approx length of day
eqtime = calcEquationOfTime(t)
solarDec = calcSunDeclination(t)
hourangle = calcHourAngleSunset(latitude, solarDec)
delta = longitude - radToDeg(hourangle)
timeDiff = 4 * delta
timeUTC = 720 + timeDiff - eqtime
' // first pass used to include fractional day in gamma calc
newt = calcTimeJulianCent(calcJDFromJulianCent(t) + timeUTC / 1440#)
eqtime = calcEquationOfTime(newt)
solarDec = calcSunDeclination(newt)
hourangle = calcHourAngleDusk(latitude, solarDec, solardepression)
delta = longitude - radToDeg(hourangle)
timeDiff = 4 * delta
timeUTC = 720 + timeDiff - eqtime
' // in minutes
calcDuskUTC = timeUTC
End Function
Function Dawn(lat, lon, year, month, day, timezone, dlstime, solardepression)
'***********************************************************************/
'* Name: dawn
'* Type: Main Function called by spreadsheet
'* Purpose: calculate time of dawn for the entered date
'* and location.
'* For latitudes greater than 72 degrees N and S, calculations are
'* accurate to within 10 minutes. For latitudes less than +/- 72°
'* accuracy is approximately one minute.
'* Arguments:
' latitude = latitude (decimal degrees)
' longitude = longitude (decimal degrees)
' NOTE: longitude is negative for western hemisphere for input cells
' in the spreadsheet for calls to the functions named
' sunrise, solarnoon, and sunset. Those functions convert the
' longitude to positive for the western hemisphere for calls to
' other functions using the original sign convention
' from the NOAA javascript code.
' year = year
' month = month
' day = day
' timezone = time zone hours relative to GMT/UTC (hours)
' dlstime = daylight savings time (0 = no, 1 = yes) (hours)
' solardepression = angle of sun below horizon in degrees
'* Return value:
'* dawn time in local time (days)
'***********************************************************************/
Dim longitude As Double, latitude As Double, JD As Double
Dim riseTimeGMT As Double, riseTimeLST As Double
' change sign convention for longitude from negative to positive in western hemisphere
longitude = lon * -1
latitude = lat
If (latitude > 89.8) Then latitude = 89.8
If (latitude < -89.8) Then latitude = -89.8
JD = calcJD(year, month, day)
' // Calculate sunrise for this date
riseTimeGMT = calcDawnUTC(JD, latitude, longitude, solardepression)
' // adjust for time zone and daylight savings time in minutes
riseTimeLST = riseTimeGMT + (60 * timezone) + (dlstime * 60)
' // convert to days
Dawn = riseTimeLST / 1440
End Function
Function sunrise(lat, lon, year, month, day, timezone, dlstime)
'***********************************************************************/
'* Name: sunrise
'* Type: Main Function called by spreadsheet
'* Purpose: calculate time of sunrise for the entered date
'* and location.
'* For latitudes greater than 72 degrees N and S, calculations are
'* accurate to within 10 minutes. For latitudes less than +/- 72°
'* accuracy is approximately one minute.
'* Arguments:
' latitude = latitude (decimal degrees)
' longitude = longitude (decimal degrees)
' NOTE: longitude is negative for western hemisphere for input cells
' in the spreadsheet for calls to the functions named
' sunrise, solarnoon, and sunset. Those functions convert the
' longitude to positive for the western hemisphere for calls to
' other functions using the original sign convention
' from the NOAA javascript code.
' year = year
' month = month
' day = day
' timezone = time zone hours relative to GMT/UTC (hours)
' dlstime = daylight savings time (0 = no, 1 = yes) (hours)
'* Return value:
'* sunrise time in local time (days)
'***********************************************************************/
Dim longitude As Double, latitude As Double, JD As Double
Dim riseTimeGMT As Double, riseTimeLST As Double
' change sign convention for longitude from negative to positive in western hemisphere
longitude = lon * -1
latitude = lat
If (latitude > 89.8) Then latitude = 89.8
If (latitude < -89.8) Then latitude = -89.8
JD = calcJD(year, month, day)
' // Calculate sunrise for this date
riseTimeGMT = calcSunriseUTC(JD, latitude, longitude)
' // adjust for time zone and daylight savings time in minutes
riseTimeLST = riseTimeGMT + (60 * timezone) + (dlstime * 60)
' // convert to days
sunrise = riseTimeLST / 1440
End Function
Function solarnoon(lat, lon, year, month, day, timezone, dlstime)
'***********************************************************************/
'* Name: solarnoon
'* Type: Main Function called by spreadsheet
'* Purpose: calculate the Universal Coordinated Time (UTC) of solar
'* noon for the given day at the given location on earth
'* Arguments:
' year
' month
' day
'* longitude : longitude of observer in degrees
' NOTE: longitude is negative for western hemisphere for input cells
' in the spreadsheet for calls to the functions named
' sunrise, solarnoon, and sunset. Those functions convert the
' longitude to positive for the western hemisphere for calls to
' other functions using the original sign convention
' from the NOAA javascript code.
'* Return value:
'* time of solar noon in local time days
'***********************************************************************/
Dim longitude As Double, latitude As Double, JD As Double
Dim t As Double, newt As Double, eqtime As Double
Dim solarNoonDec As Double, solNoonUTC As Double
' change sign convention for longitude from negative to positive in western hemisphere
longitude = lon * -1
latitude = lat
If (latitude > 89.8) Then latitude = 89.8
If (latitude < -89.8) Then latitude = -89.8
JD = calcJD(year, month, day)
t = calcTimeJulianCent(JD)
newt = calcTimeJulianCent(calcJDFromJulianCent(t) + 0.5 + longitude / 360#)
eqtime = calcEquationOfTime(newt)
solarNoonDec = calcSunDeclination(newt)
solNoonUTC = 720 + (longitude * 4) - eqtime
' // adjust for time zone and daylight savings time in minutes
solarnoon = solNoonUTC + (60 * timezone) + (dlstime * 60)
' // convert to days
solarnoon = solarnoon / 1440
End Function
Function sunset(lat, lon, year, month, day, timezone, dlstime)
'***********************************************************************/
'* Name: sunset
'* Type: Main Function called by spreadsheet
'* Purpose: calculate time of sunrise and sunset for the entered date
'* and location.
'* For latitudes greater than 72 degrees N and S, calculations are
'* accurate to within 10 minutes. For latitudes less than +/- 72°
'* accuracy is approximately one minute.
'* Arguments:
' latitude = latitude (decimal degrees)
' longitude = longitude (decimal degrees)
' NOTE: longitude is negative for western hemisphere for input cells
' in the spreadsheet for calls to the functions named
' sunrise, solarnoon, and sunset. Those functions convert the
' longitude to positive for the western hemisphere for calls to
' other functions using the original sign convention
' from the NOAA javascript code.
' year = year
' month = month
' day = day
' timezone = time zone hours relative to GMT/UTC (hours)
' dlstime = daylight savings time (0 = no, 1 = yes) (hours)
'* Return value:
'* sunset time in local time (days)
'***********************************************************************/
Dim longitude As Double, latitude As Double, JD As Double
Dim setTimeGMT As Double, setTimeLST As Double
' change sign convention for longitude from negative to positive in western hemisphere
longitude = lon * -1
latitude = lat
If (latitude > 89.8) Then latitude = 89.8
If (latitude < -89.8) Then latitude = -89.8
JD = calcJD(year, month, day)
' // Calculate sunset for this date
setTimeGMT = calcSunsetUTC(JD, latitude, longitude)
' // adjust for time zone and daylight savings time in minutes
setTimeLST = setTimeGMT + (60 * timezone) + (dlstime * 60)
' // convert to days
sunset = setTimeLST / 1440
End Function
Function Dusk(lat, lon, year, month, day, timezone, dlstime, solardepression)
'***********************************************************************/
'* Name: dusk
'* Type: Main Function called by spreadsheet
'* Purpose: calculate time of sunrise and sunset for the entered date
'* and location.
'* For latitudes greater than 72 degrees N and S, calculations are
'* accurate to within 10 minutes. For latitudes less than +/- 72°
'* accuracy is approximately one minute.
'* Arguments:
' latitude = latitude (decimal degrees)
' longitude = longitude (decimal degrees)
' NOTE: longitude is negative for western hemisphere for input cells
' in the spreadsheet for calls to the functions named
' sunrise, solarnoon, and sunset. Those functions convert the
' longitude to positive for the western hemisphere for calls to
' other functions using the original sign convention
' from the NOAA javascript code.
' year = year
' month = month
' day = day
' timezone = time zone hours relative to GMT/UTC (hours)
' dlstime = daylight savings time (0 = no, 1 = yes) (hours)
' solardepression = angle of sun below horizon in degrees
'* Return value:
'* dusk time in local time (days)
'***********************************************************************/
Dim longitude As Double, latitude As Double, JD As Double
Dim setTimeGMT As Double, setTimeLST As Double
' change sign convention for longitude from negative to positive in western hemisphere
longitude = lon * -1
latitude = lat
If (latitude > 89.8) Then latitude = 89.8
If (latitude < -89.8) Then latitude = -89.8
JD = calcJD(year, month, day)
' // Calculate sunset for this date
setTimeGMT = calcDuskUTC(JD, latitude, longitude, solardepression)
' // adjust for time zone and daylight savings time in minutes
setTimeLST = setTimeGMT + (60 * timezone) + (dlstime * 60)
' // convert to days
Dusk = setTimeLST / 1440
End Function
Function solarazimuth(lat, lon, year, month, day, _
hours, minutes, seconds, timezone, dlstime)
'***********************************************************************/
'* Name: solarazimuth
'* Type: Main Function
'* Purpose: calculate solar azimuth (deg from north) for the entered
'* date, time and location. Returns -999999 if darker than twilight
'*
'* Arguments:
'* latitude, longitude, year, month, day, hour, minute, second,
'* timezone, daylightsavingstime
'* Return value:
'* solar azimuth in degrees from north
'*
'* Note: solarelevation and solarazimuth functions are identical
'* and could be converted to a VBA subroutine that would return
'* both values.
'*
'***********************************************************************/
Dim longitude As Double, latitude As Double
Dim zone As Double, daySavings As Double
Dim hh As Double, mm As Double, ss As Double, timenow As Double
Dim JD As Double, t As Double, R As Double
Dim alpha As Double, theta As Double, Etime As Double, eqtime As Double
Dim solarDec As Double, earthRadVec As Double, solarTimeFix As Double
Dim trueSolarTime As Double, hourangle As Double, harad As Double
Dim csz As Double, zenith As Double, azDenom As Double, azRad As Double
Dim azimuth As Double, exoatmElevation As Double
Dim step1 As Double, step2 As Double, step3 As Double
Dim refractionCorrection As Double, te As Double, solarzen As Double
' change sign convention for longitude from negative to positive in western hemisphere
longitude = lon * -1
latitude = lat
If (latitude > 89.8) Then latitude = 89.8
If (latitude < -89.8) Then latitude = -89.8
'change time zone to ppositive hours in western hemisphere
zone = timezone * -1
daySavings = dlstime * 60
hh = hours - (daySavings / 60)
mm = minutes
ss = seconds
'// timenow is GMT time for calculation in hours since 0Z
timenow = hh + mm / 60 + ss / 3600 + zone
JD = calcJD(year, month, day)
t = calcTimeJulianCent(JD + timenow / 24#)
R = calcSunRadVector(t)
alpha = calcSunRtAscension(t)
theta = calcSunDeclination(t)
Etime = calcEquationOfTime(t)
eqtime = Etime
solarDec = theta '// in degrees
earthRadVec = R
solarTimeFix = eqtime - 4# * longitude + 60# * zone
trueSolarTime = hh * 60# + mm + ss / 60# + solarTimeFix
'// in minutes
Do While (trueSolarTime > 1440)
trueSolarTime = trueSolarTime - 1440
Loop
hourangle = trueSolarTime / 4# - 180#
'// Thanks to Louis Schwarzmayr for the next line:
If (hourangle < -180) Then hourangle = hourangle + 360#
harad = degToRad(hourangle)
csz = Sin(degToRad(latitude)) * _
Sin(degToRad(solarDec)) + _
Cos(degToRad(latitude)) * _
Cos(degToRad(solarDec)) * Cos(harad)
If (csz > 1#) Then
csz = 1#
ElseIf (csz < -1#) Then
csz = -1#
End If
zenith = radToDeg(Acos(csz))
azDenom = (Cos(degToRad(latitude)) * Sin(degToRad(zenith)))
If (Abs(azDenom) > 0.001) Then
azRad = ((Sin(degToRad(latitude)) * _
Cos(degToRad(zenith))) - _
Sin(degToRad(solarDec))) / azDenom
If (Abs(azRad) > 1#) Then
If (azRad < 0) Then
azRad = -1#
Else
azRad = 1#
End If
End If
azimuth = 180# - radToDeg(Acos(azRad))
If (hourangle > 0#) Then
azimuth = -azimuth
End If
Else
If (latitude > 0#) Then
azimuth = 180#
Else
azimuth = 0#
End If
End If
If (azimuth < 0#) Then
azimuth = azimuth + 360#
End If
exoatmElevation = 90# - zenith
'beginning of complex expression commented out
' If (exoatmElevation > 85#) Then
' refractionCorrection = 0#
' Else
' te = Tan(degToRad(exoatmElevation))
' If (exoatmElevation > 5#) Then
' refractionCorrection = 58.1 / te - 0.07 / (te * te * te) + _
' 0.000086 / (te * te * te * te * te)
' ElseIf (exoatmElevation > -0.575) Then
' refractionCorrection = 1735# + exoatmElevation * _
' (-518.2 + exoatmElevation * (103.4 + _
' exoatmElevation * (-12.79 + _
' exoatmElevation * 0.711)))
' Else
' refractionCorrection = -20.774 / te
' End If
' refractionCorrection = refractionCorrection / 3600#
' End If
'end of complex expression
'beginning of simplified expression
If (exoatmElevation > 85#) Then
refractionCorrection = 0#
Else
te = Tan(degToRad(exoatmElevation))
If (exoatmElevation > 5#) Then
refractionCorrection = 58.1 / te - 0.07 / (te * te * te) + _
0.000086 / (te * te * te * te * te)
ElseIf (exoatmElevation > -0.575) Then
step1 = (-12.79 + exoatmElevation * 0.711)
step2 = (103.4 + exoatmElevation * (step1))
step3 = (-518.2 + exoatmElevation * (step2))
refractionCorrection = 1735# + exoatmElevation * (step3)
Else
refractionCorrection = -20.774 / te
End If
refractionCorrection = refractionCorrection / 3600#
End If
'end of simplified expression
solarzen = zenith - refractionCorrection
' If (solarZen < 108#) Then
solarazimuth = azimuth
' solarelevation = 90# - solarZen
' If (solarZen < 90#) Then
' coszen = Cos(degToRad(solarZen))
' Else
' coszen = 0#
' End If
' Else '// do not report az & el after astro twilight
' solarazimuth = -999999
' solarelevation = -999999
' coszen = -999999
' End If
End Function
Function solarelevation(lat, lon, year, month, day, _
hours, minutes, seconds, timezone, dlstime)
'***********************************************************************/
'* Name: solarazimuth
'* Type: Main Function
'* Purpose: calculate solar azimuth (deg from north) for the entered
'* date, time and location. Returns -999999 if darker than twilight
'*
'* Arguments:
'* latitude, longitude, year, month, day, hour, minute, second,
'* timezone, daylightsavingstime
'* Return value:
'* solar azimuth in degrees from north
'*
'* Note: solarelevation and solarazimuth functions are identical
'* and could converted to a VBA subroutine that would return
'* both values.
'*
'***********************************************************************/
Dim longitude As Double, latitude As Double
Dim zone As Double, daySavings As Double
Dim hh As Double, mm As Double, ss As Double, timenow As Double
Dim JD As Double, t As Double, R As Double
Dim alpha As Double, theta As Double, Etime As Double, eqtime As Double
Dim solarDec As Double, earthRadVec As Double, solarTimeFix As Double
Dim trueSolarTime As Double, hourangle As Double, harad As Double
Dim csz As Double, zenith As Double, azDenom As Double, azRad As Double
Dim azimuth As Double, exoatmElevation As Double
Dim step1 As Double, step2 As Double, step3 As Double
Dim refractionCorrection As Double, te As Double, solarzen As Double
' change sign convention for longitude from negative to positive in western hemisphere
longitude = lon * -1
latitude = lat
If (latitude > 89.8) Then latitude = 89.8
If (latitude < -89.8) Then latitude = -89.8
'change time zone to ppositive hours in western hemisphere
zone = timezone * -1
daySavings = dlstime * 60
hh = hours - (daySavings / 60)
mm = minutes
ss = seconds
'// timenow is GMT time for calculation in hours since 0Z
timenow = hh + mm / 60 + ss / 3600 + zone
JD = calcJD(year, month, day)
t = calcTimeJulianCent(JD + timenow / 24#)
R = calcSunRadVector(t)
alpha = calcSunRtAscension(t)
theta = calcSunDeclination(t)
Etime = calcEquationOfTime(t)
eqtime = Etime
solarDec = theta '// in degrees
earthRadVec = R
solarTimeFix = eqtime - 4# * longitude + 60# * zone
trueSolarTime = hh * 60# + mm + ss / 60# + solarTimeFix
'// in minutes
Do While (trueSolarTime > 1440)
trueSolarTime = trueSolarTime - 1440
Loop
hourangle = trueSolarTime / 4# - 180#
'// Thanks to Louis Schwarzmayr for the next line:
If (hourangle < -180) Then hourangle = hourangle + 360#
harad = degToRad(hourangle)
csz = Sin(degToRad(latitude)) * _
Sin(degToRad(solarDec)) + _
Cos(degToRad(latitude)) * _
Cos(degToRad(solarDec)) * Cos(harad)
If (csz > 1#) Then
csz = 1#
ElseIf (csz < -1#) Then
csz = -1#
End If
zenith = radToDeg(Acos(csz))
azDenom = (Cos(degToRad(latitude)) * Sin(degToRad(zenith)))
If (Abs(azDenom) > 0.001) Then
azRad = ((Sin(degToRad(latitude)) * _
Cos(degToRad(zenith))) - _
Sin(degToRad(solarDec))) / azDenom
If (Abs(azRad) > 1#) Then
If (azRad < 0) Then
azRad = -1#
Else
azRad = 1#
End If
End If
azimuth = 180# - radToDeg(Acos(azRad))
If (hourangle > 0#) Then
azimuth = -azimuth
End If
Else
If (latitude > 0#) Then
azimuth = 180#
Else
azimuth = 0#
End If
End If
If (azimuth < 0#) Then
azimuth = azimuth + 360#
End If
exoatmElevation = 90# - zenith
'beginning of complex expression commented out
' If (exoatmElevation > 85#) Then
' refractionCorrection = 0#
' Else
' te = Tan(degToRad(exoatmElevation))
' If (exoatmElevation > 5#) Then
' refractionCorrection = 58.1 / te - 0.07 / (te * te * te) + _
' 0.000086 / (te * te * te * te * te)
' ElseIf (exoatmElevation > -0.575) Then
' refractionCorrection = 1735# + exoatmElevation * _
' (-518.2 + exoatmElevation * (103.4 + _
' exoatmElevation * (-12.79 + _
' exoatmElevation * 0.711)))
' Else
' refractionCorrection = -20.774 / te
' End If
' refractionCorrection = refractionCorrection / 3600#
' End If
'end of complex expression
'beginning of simplified expression
If (exoatmElevation > 85#) Then
refractionCorrection = 0#
Else
te = Tan(degToRad(exoatmElevation))
If (exoatmElevation > 5#) Then
refractionCorrection = 58.1 / te - 0.07 / (te * te * te) + _
0.000086 / (te * te * te * te * te)
ElseIf (exoatmElevation > -0.575) Then
step1 = (-12.79 + exoatmElevation * 0.711)
step2 = (103.4 + exoatmElevation * (step1))
step3 = (-518.2 + exoatmElevation * (step2))
refractionCorrection = 1735# + exoatmElevation * (step3)
Else
refractionCorrection = -20.774 / te
End If
refractionCorrection = refractionCorrection / 3600#
End If
'end of simplified expression
solarzen = zenith - refractionCorrection
' If (solarZen < 108#) Then
' solarazimuth = azimuth
solarelevation = 90# - solarzen
' If (solarZen < 90#) Then
' coszen = Cos(degToRad(solarZen))
' Else
' coszen = 0#
' End If
' Else '// do not report az & el after astro twilight
' solarazimuth = -999999
' solarelevation = -999999
' coszen = -999999
' End If
End Function
Sub solarposition(lat, lon, year, month, day, _
hours, minutes, seconds, timezone, dlstime, solarazimuth, solarelevation)
'***********************************************************************/
'* Name: solarazimuth
'* Type: Main Function
'* Purpose: calculate solar azimuth (deg from north) for the entered
'* date, time and location. Returns -999999 if darker than twilight
'*
'* Arguments:
'* latitude, longitude, year, month, day, hour, minute, second,
'* timezone, daylightsavingstime
'* Return value:
'* solar azimuth in degrees from north
'*
'* Note: solarelevation and solarazimuth functions are identical
'* and could converted to a VBA subroutine that would return
'* both values.
'*
'***********************************************************************/
Dim longitude As Double, latitude As Double
Dim zone As Double, daySavings As Double
Dim hh As Double, mm As Double, ss As Double, timenow As Double
Dim JD As Double, t As Double, R As Double
Dim alpha As Double, theta As Double, Etime As Double, eqtime As Double
Dim solarDec As Double, earthRadVec As Double, solarTimeFix As Double
Dim trueSolarTime As Double, hourangle As Double, harad As Double
Dim csz As Double, zenith As Double, azDenom As Double, azRad As Double
Dim azimuth As Double, exoatmElevation As Double
Dim step1 As Double, step2 As Double, step3 As Double
Dim refractionCorrection As Double, te As Double, solarzen As Double
' change sign convention for longitude from negative to positive in western hemisphere
longitude = lon * -1
latitude = lat
If (latitude > 89.8) Then latitude = 89.8
If (latitude < -89.8) Then latitude = -89.8
'change time zone to ppositive hours in western hemisphere
zone = timezone * -1
daySavings = dlstime * 60
hh = hours - (daySavings / 60)
mm = minutes
ss = seconds
'// timenow is GMT time for calculation in hours since 0Z
timenow = hh + mm / 60 + ss / 3600 + zone
JD = calcJD(year, month, day)
t = calcTimeJulianCent(JD + timenow / 24#)
R = calcSunRadVector(t)
alpha = calcSunRtAscension(t)
theta = calcSunDeclination(t)
Etime = calcEquationOfTime(t)
eqtime = Etime
solarDec = theta '// in degrees
earthRadVec = R
solarTimeFix = eqtime - 4# * longitude + 60# * zone
trueSolarTime = hh * 60# + mm + ss / 60# + solarTimeFix
'// in minutes
Do While (trueSolarTime > 1440)
trueSolarTime = trueSolarTime - 1440
Loop
hourangle = trueSolarTime / 4# - 180#
'// Thanks to Louis Schwarzmayr for the next line:
If (hourangle < -180) Then hourangle = hourangle + 360#
harad = degToRad(hourangle)
csz = Sin(degToRad(latitude)) * _
Sin(degToRad(solarDec)) + _
Cos(degToRad(latitude)) * _
Cos(degToRad(solarDec)) * Cos(harad)
If (csz > 1#) Then
csz = 1#
ElseIf (csz < -1#) Then
csz = -1#
End If
zenith = radToDeg(Acos(csz))
azDenom = (Cos(degToRad(latitude)) * Sin(degToRad(zenith)))
If (Abs(azDenom) > 0.001) Then
azRad = ((Sin(degToRad(latitude)) * _
Cos(degToRad(zenith))) - _
Sin(degToRad(solarDec))) / azDenom
If (Abs(azRad) > 1#) Then
If (azRad < 0) Then
azRad = -1#
Else
azRad = 1#
End If
End If
azimuth = 180# - radToDeg(Acos(azRad))
If (hourangle > 0#) Then
azimuth = -azimuth
End If
Else
If (latitude > 0#) Then
azimuth = 180#
Else
azimuth = 0#
End If
End If
If (azimuth < 0#) Then
azimuth = azimuth + 360#
End If
exoatmElevation = 90# - zenith
'beginning of complex expression commented out
' If (exoatmElevation > 85#) Then
' refractionCorrection = 0#
' Else
' te = Tan(degToRad(exoatmElevation))
' If (exoatmElevation > 5#) Then
' refractionCorrection = 58.1 / te - 0.07 / (te * te * te) + _
' 0.000086 / (te * te * te * te * te)
' ElseIf (exoatmElevation > -0.575) Then
' refractionCorrection = 1735# + exoatmElevation * _
' (-518.2 + exoatmElevation * (103.4 + _
' exoatmElevation * (-12.79 + _
' exoatmElevation * 0.711)))
' Else
' refractionCorrection = -20.774 / te
' End If
' refractionCorrection = refractionCorrection / 3600#
' End If
'end of complex expression
'beginning of simplified expression
If (exoatmElevation > 85#) Then
refractionCorrection = 0#
Else
te = Tan(degToRad(exoatmElevation))
If (exoatmElevation > 5#) Then
refractionCorrection = 58.1 / te - 0.07 / (te * te * te) + _
0.000086 / (te * te * te * te * te)
ElseIf (exoatmElevation > -0.575) Then
step1 = (-12.79 + exoatmElevation * 0.711)
step2 = (103.4 + exoatmElevation * (step1))
step3 = (-518.2 + exoatmElevation * (step2))
refractionCorrection = 1735# + exoatmElevation * (step3)
Else
refractionCorrection = -20.774 / te
End If
refractionCorrection = refractionCorrection / 3600#
End If
'end of simplified expression
solarzen = zenith - refractionCorrection
' If (solarZen < 108#) Then
solarazimuth = azimuth
solarelevation = 90# - solarzen
' If (solarZen < 90#) Then
' coszen = Cos(degToRad(solarZen))
' Else
' coszen = 0#
' End If
' Else '// do not report az & el after astro twilight
' solarazimuth = -999999
' solarelevation = -999999
' coszen = -999999
' End If
End Sub
Public Function Pi()
Pi = 4 * Atn(1)
End Function
Public Function Floor(ByVal X As Double, Optional ByVal Factor As Double = 1) As Double
Floor = Int(X / Factor) * Factor
End Function
Public Function Acos(ByVal Arg1 As Double)
Acos = Atn(-Arg1 / Sqr(-Arg1 * Arg1 + 1)) + 2 * Atn(1)
End Function
Public Function Asin(ByVal Arg1 As Double)
Asin = Atn(Arg1 / Sqr(-Arg1 * Arg1 + 1))
End Function
Public Function Atan2(ByVal Y As Double, ByVal X As Double) As Double
If X = 0 And Y = 0 Then
Atan2 = 0
ElseIf X <> 0 Then
Atan2 = Atn(Y / X) - Pi * (X < 0) * (2 * (Y < 0) - 1)
Else
Atan2 = Pi / 2 * (2 * (Y > 0) - 1)
End If
End Function
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