I realize this is a bit of an old post, but has anyone come across a function for State Plane projections that are in Transverse Mercator (Like Nevada, Arizona, etc)? It seems like there are many functions out there for SP in the Conformal Conic and UTM zones (like the one above), but I haven't had any luck with the SP in TM.
So, has anyone come across anything like that? I tried using the above function and modifying it a bit and that did not work out for me. I guess the SP in TM requires a little bit different math than UTM zones...
Edit:
I wanted to attach the code I was attempting to use. I changed it up a bit to work in VB. Also, my original XY units are in feet, so I that is why you see the Dim easting As Double = y * 0.3048006096012, to change it to meters
Function StateTMDD(ByVal x As Double, ByVal y As Double) As PointN
Dim MapPoint As New PointN
'The math in this function was based off of methods found on httpas'www.gpsy.com/gpsinfo/geotoutm/ by Karen Nakamura
'Set easting and northing from the MapPoint
Dim easting As Double = y * 0.3048006096012 'the X coordinate from the service in UTM meters
Dim northing As Double = x * 0.3048006096012 'the Y coordinate from the service in UTM meters
Dim avflat As Double = 298.257223563 'the Inverse Flattening that ArcGIS provides in the geographic coordinate description
Dim semiMAJaxis As Double = 6378137.0 'the Semimajor Axis that ArcGIS provides in the geographic coordinate description
Dim meridORIG As Double = -118.583333 'the Central Meridian that ArcGIS provides in the projection description
Dim scFACTorig As Double = 0.9999 'the Scale Factor that ArcGIS provides in the projection description
Dim falseNOR As Double = 400000 'the False Northing that ArcGIS provides in the projection description
Dim falseEST As Double = 80000 'the False Easting that ArcGIS provides in the projection description
Dim latORG As Double = 34.75 'Latitude of Origin
'Calculations
Dim flattening As Double = 1.0 / avflat 'change Inverse Flattening into flattening
Dim eccentricity As Double = 0.08181905782 'calculate eccentricity (2.0 * flattening) - (flattening * flattening)
Dim semiMINaxis As Double = 6356752.3141403561 'calculate the Semiminor Axis semiMAJaxis * (Math.Pow((1.0 - eccentricity), 0.5))
Dim n As Double = (semiMAJaxis - semiMINaxis) / (semiMAJaxis + semiMINaxis) 'calculate n
Dim semiMAJecc As Double = semiMAJaxis * (1.0 - eccentricity) 'calculate the Semimajor Eccentricity
Dim semiMINecc As Double = 1.0 / (Math.Sin((1.0 / 3600.0) * Math.PI / 180.0)) 'calculate the Semiminor Eccentricity
Dim epsilon As Double = 1097.0 * (Math.Pow(n, 4.0)) / 512.0 'calculate epsilon
Dim delta As Double = 151.0 * (Math.Pow(n, 3.0)) / 96.0 - (417.0 * (Math.Pow(n, 5.0)) / 128.0) 'calculate delta
Dim gamma As Double = 21.0 * (Math.Pow(n, 2.0)) / 16.0 - (55.0 * (Math.Pow(n, 4.0)) / 32.0) 'calculate gamma
Dim beta As Double = 3.0 * n / 2.0 - (27.0 * (Math.Pow(n, 3.0)) / 32.0) + (269.0 * (Math.Pow(n, 5.0)) / 512.0) 'calculate beta
Dim alpha As Double = (semiMAJaxis + semiMINaxis) / 2.0 * (1.0 + (Math.Pow(n, 2.0)) / 4.0 + (Math.Pow(n, 4.0)) / 64.0) 'calculate alpha
Dim phiprime As Double = (northing - falseNOR) / (scFACTorig * alpha) 'calculate phiprime
Dim phiF As Double = phiprime + beta * Math.Sin(2.0 * phiprime) + gamma * Math.Sin(4.0 * phiprime) + delta * Math.Sin(6.0 * phiprime) + epsilon * Math.Sin(8.0 * phiprime) 'calculate phiF
Dim v As Double = semiMAJaxis / (Math.Pow(1.0 - (eccentricity * (Math.Pow(Math.Sin(phiF), 2.0))), 0.5)) 'calculate v
Dim p As Double = semiMAJecc / Math.Pow((1.0 - (eccentricity * Math.Pow(Math.Sin(phiF), 2.0))), 1.5) 'calculate p
Dim VII As Double = ((Math.Tan(phiF) * Math.Pow((easting - falseEST), 2.0)) / (2.0 * Math.Pow(scFACTorig, 2.0) * v * p)) * ((1.0 / (Math.Sin((1.0 / 3600.0) * Math.PI / 180.0)))) 'calculate VII
Dim VIII As Double = ((Math.Tan(phiF) * Math.Pow((easting - falseEST), 4.0)) / (24.0 * Math.Pow(scFACTorig, 4.0) * Math.Pow(v, 3.0) * p)) * (5.0 + 3.0 * Math.Pow((Math.Tan(phiF)), 2.0)) * (1.0 / (Math.Sin((1.0 / 3600.0) * Math.PI / 180.0))) 'calculate VIII
Dim Ten As Double = ((1.0 / Math.Cos(phiF)) * Math.Pow((easting - falseEST), 3.0) * semiMINecc) / (6.0 * Math.Pow(scFACTorig, 3.0) * Math.Pow(v, 3.0)) * ((v / p) + 2.0 * Math.Pow((Math.Tan(phiF)), 2.0)) 'calculate X
Dim IX As Double = ((1.0 / Math.Cos(phiF)) * (easting - falseEST) * semiMINecc) / (scFACTorig * v) 'calculate XI
Dim E As Double = ((1.0 / Math.Cos(phiF)) * Math.Pow((easting - falseEST), 5.0) * semiMINecc) / (120.0 * Math.Pow(scFACTorig, 5.0) * Math.Pow(v, 5.0)) * (5.0 + 28.0 * Math.Pow((Math.Tan(phiF)), 2.0) + 24.0 * Math.Pow((Math.Tan(phiF)), 4.0)) 'calculate E
Dim phiFdegrees As Double = phiF * 180.0 / Math.PI 'change phiF from radians to degrees
Dim DDegLat As Double = (phiFdegrees - VII / 3600.0 + VIII / 3600.0) + latORG 'calculate degrees latitude
Dim DDegLon As Double = meridORIG + (IX - Ten + E) / 3600.0 'calculate degrees longitude
'Set the MapPoint to the new Lat and Lon
MapPoint.X = DDegLon
MapPoint.Y = DDegLat
'Return the MapPoint
Return MapPoint
