@spiceErrorCheck<EOL>def nearpt(positn, a, b, c):
positn = stypes.toDoubleVector(positn)<EOL>a = ctypes.c_double(a)<EOL>b = ctypes.c_double(b)<EOL>c = ctypes.c_double(c)<EOL>npoint = stypes.emptyDoubleVector(<NUM_LIT:3>)<EOL>alt = ctypes.c_double()<EOL>libspice.nearpt_c(positn, a, b, c, npoint, ctypes.byref(alt))<EOL>return stypes.cVectorToPython(npoint), alt.value<EOL>
locates the point on the surface of an ellipsoid that is nearest to a
specified position. It also returns the altitude of the
position above the ellipsoid.

http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/nearpt_c.html

:param positn: Position of a point in bodyfixed frame.
:type positn: 3-Element Array of floats
:param a: Length of semi-axis parallel to x-axis.
:type a: float
:param b: Length of semi-axis parallel to y-axis.
:type b: float
:param c: Length on semi-axis parallel to z-axis.
:type c: float
:return:
        Point on the ellipsoid closest to positn,
        Altitude of positn above the ellipsoid.
:rtype: tuple