IceCast (version 2.1.0)

mapxy: Get geodetic latitudes and longitudes

Description

Get corresponding latitude and longitude values for coordinates on a Polar Stereographic North projection grid

Usage

mapxy(X, Y, sgn = 1, slat = 70, re = 6378.273, e2 = 0.006693883,
  degrees = TRUE)

Arguments

X

Polar Stereographic X Coordinate (km)

Y

Polar Stereographic Y Coordinate (km)

sgn

indicator for Northern hemisphere (defaults to 1)

slat

standard latitude (defaults to 70)

re

Earth's radius (defaults to 6378.273)

e2

eccentricity squared (defaults to 0.006693883)

degrees

boolean indicating whether result should be returned in degrees or radians

Value

list with elements coords$aLat, the geodetic latitude (degrees, +90 to -90), and coords$aLon, the geodetic longitude (degrees, -180 to 180)

References

The equations for this calculation are from Snyder, J. P., 1982, Map Projections Used by the U.S. Geological Survey, Geological Survey Bulletin 1532, U.S. Government Printing Office. See JPL Technical Memorandum 3349-85-101 for further details.

Examples

# NOT RUN {
new <- mapxy(100, 300)
new$alat
new$alon
# }