HCwi:
--------------------------------------------------------------------------
Interface to HCw.
--------------------------------------------------------------------------
Form:
w = HCwi( x, u )
--------------------------------------------------------------------------
------
Inputs
------
x State vector [ra, dec, dcant, dearthRadius, bias]
u Auxiliary vector [cant;er;ue]
-------
Outputs
-------
w Chordwidth
--------------------------------------------------------------------------
Children:
SAAD: SAAttDet/HCw