Covert lat, lon, alt to ECEF Cartesian

LLA2ECEF - convert latitude, longitude, and altitude to earth-centered, earth-fixed (ECEF) cartesian coordinates

USAGE:
[x,y,z] = lla2ecef(lat,lon,alt)

x = ECEF X-coordinate (m)
y = ECEF Y-coordinate (m)
z = ECEF Z-coordinate (m)
lat = geodetic latitude (radians)
lon = longitude (radians)
alt = height above WGS84 ellipsoid (m)

Notes: This function assumes the WGS84 model. Latitude is customary geodetic (not geocentric).

Source: "Department of Defense World Geodetic System 1984," Page 4-4. National Imagery and Mapping Agency. NIMA TR8350.2

Michael Kleder, July 2005