@spiceErrorCheck<EOL>def vsep(v1, v2):
v1 = stypes.toDoubleVector(v1)<EOL>v2 = stypes.toDoubleVector(v2)<EOL>return libspice.vsep_c(v1, v2)<EOL>
Find the separation angle in radians between two double
precision, 3-dimensional vectors. This angle is defined as zero
if either vector is zero.

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

:param v1: First vector 
:type v1: 3-Element Array of floats
:param v2: Second vector 
:type v2: 3-Element Array of floats
:return: separation angle in radians
:rtype: float