proyectar latitud a y mercator

#!/usr/bin/python

#
# The mercator projection 
#
# http://mathworld.wolfram.com/MercatorProjection.html
#

import math

def getMercatorYfromLatitude(lat):

    lat = float(lat)
   
    if (lat > 90) : lat = lat - 180
    if (lat < -90) : lat = lat + 180

    phi = math.radians(lat)
    y = 0.5 * math.log( (1.0 + math.sin(phi)) / (1.0 - math.sin(phi)) )

    return y
    
#    maxlat = math.pi
#    maxTileY = math.pow(2, zoom)
#    result =  int( 0.5 * (1 - y / maxlat) * (maxTileY) )  
#    return (result);

def getLatitudeFromMercatorY(mercatorY):

    phi = ( 2.0 * math.atan ( math.exp(mercatorY) ) ) - ( 0.5 * math.pi)
    lat = math.degrees(phi)

    return (lat)                            

if __name__ == "__main__":

   c0 = 43.1742630005
   m = getMercatorYfromLatitude(c0)
   c = getLatitudeFromMercatorY(m)
   print c0
   print m
   print c