Source code for lenstronomy.LensModel.Profiles.constant_shift
__author__ = "sibirrer"
from lenstronomy.LensModel.Profiles.base_profile import LensProfileBase
import numpy as np
__all__ = ["Shift"]
[docs]
class Shift(LensProfileBase):
"""Lens model with a constant shift of the deflection field."""
param_names = ["alpha_x", "alpha_y"]
lower_limit_default = {"alpha_x": -1000, "alpha_y": -1000}
upper_limit_default = {"alpha_x": 1000, "alpha_y": 1000}
[docs]
def function(self, x, y, alpha_x, alpha_y):
"""
:param x: coordinate in image plane (angle)
:param y: coordinate in image plane (angle)
:param alpha_x: shift in x-direction (angle)
:param alpha_y: shift in y-direction (angle)
:return: lensing potential
"""
return np.zeros_like(x)
[docs]
def derivatives(self, x, y, alpha_x, alpha_y):
"""
:param x: coordinate in image plane (angle)
:param y: coordinate in image plane (angle)
:param alpha_x: shift in x-direction (angle)
:param alpha_y: shift in y-direction (angle)
:return: deflection in x- and y-direction
"""
f_x = np.ones_like(x) * alpha_x
f_y = np.ones_like(x) * alpha_y
return f_x, f_y
[docs]
def hessian(self, x, y, alpha_x, alpha_y):
"""
:param x: coordinate in image plane (angle)
:param y: coordinate in image plane (angle)
:param alpha_x: shift in x-direction (angle)
:param alpha_y: shift in y-direction (angle)
:return: hessian elements f_xx, f_xy, f_yx, f_yy
"""
f_xx, f_xy, f_yx, f_yy = 0, 0, 0, 0
return f_xx, f_xy, f_yx, f_yy