# SIP¶

class astropy.modeling.polynomial.SIP(crpix, a_order, b_order, a_coeff={}, b_coeff={}, ap_order=None, bp_order=None, ap_coeff={}, bp_coeff={}, n_models=None, model_set_axis=None, name=None, meta=None)[source]

Simple Imaging Polynomial (SIP) model.

The SIP convention is used to represent distortions in FITS image headers. See [R56fcfb7f2931-1] for a description of the SIP convention.

Parameters
crpixlist or ndarray of length(2)

CRPIX values

a_orderint

SIP polynomial order for first axis

b_orderint

SIP order for second axis

a_coeffdict

SIP coefficients for first axis

b_coeffdict

SIP coefficients for the second axis

ap_orderint

order for the inverse transformation (AP coefficients)

bp_orderint

order for the inverse transformation (BP coefficients)

ap_coeffdict

coefficients for the inverse transform

bp_coeffdict

coefficients for the inverse transform

References

R56fcfb7f2931-1

David Shupe, et al, ADASS, ASP Conference Series, Vol. 347, 2005

Attributes Summary

Methods Summary

 __call__(self, u, v[, model_set_axis, …]) Evaluate this model using the given input(s) and the parameter values that were specified when the model was instantiated. evaluate(self, x, y) Evaluate the model on some input variables.

Attributes Documentation

inputs = ('u', 'v')
outputs = ('x', 'y')

Methods Documentation

__call__(self, u, v, model_set_axis=None, with_bounding_box=False, fill_value=nan, equivalencies=None)

Evaluate this model using the given input(s) and the parameter values that were specified when the model was instantiated.

evaluate(self, x, y)[source]

Evaluate the model on some input variables.