def __init__(self, xv, fxv, dfxv=None, xg=None, fpxg=None, dfpxg=None, \
N=None, l=1, verbose=1, safety_factor=1.0):
"""
__init__(self, xv, fxv, dfxv=None, xg=None,
fpxg=None, dfpxg=None, N=None, l=1)
Instantiation function, see class documentation
for arguments.
fxv must has same size as xv.
dfxv must has same size as xv, or None for default
(all 0).
fpxg must be None if xg is None, or has same size
as xg if xg is not None.
dfpxg must be None if xg is None; if xg is not
None it must has same size as xg, or None for
default (all 0).
Note: beta and gamma cannot be user-specified.
They are automatically computed at every point
during initializtion (can take a while).
"""
Interp2D.__init__(self, xv, fxv, dfxv, xg, fpxg, dfpxg, 1, 1, \
N, l, verbose, safety_factor)
# calculate gammas and construct interpolation object for gamma
self.beta = self.calc_beta()
self.gamma = self.calc_gamma()
self.log_gamma_interp = Interp2D(xv, log(self.gamma), verbose=0, \
safety_factor=100)
