ism3d.arts.lens.sie_grad_abs

ism3d.arts.lens.sie_grad_abs(x, y, par)[source]
source:

http://www.physics.utah.edu/~bolton/python_lens_demo/

NAME: sie_grad

PURPOSE: compute the deflection of an SIE potential

USAGE: (xg, yg) = sie_grad(x, y, par)

ARGUMENTS:
x, y: vectors or images of coordinates;

should be matching numpy ndarrays

par: vector of parameters with 1 to 5 elements, defined as follows:

par[0]: lens strength, or ‘Einstein radius’ par[1]: (optional) x-center (default = 0.0) par[2]: (optional) y-center (default = 0.0) par[3]: (optional) axis ratio (default=1.0) par[4]: (optional) major axis Position Angle

in degrees c.c.w. of x axis. (default = 0.0)

RETURNS: tuple (xg, yg) of gradients at the positions (x, y)

NOTES: This routine implements an ‘intermediate-axis’ conventionp.
Analytic forms for the SIE potential can be found in:

Kassiola & Kovner 1993, ApJ, 417, 450 Kormann et al. 1994, A&A, 284, 285 Keeton & Kochanek 1998, ApJ, 495, 157

The parameter-order convention in this routine differs from that of a previous IDL routine of the same name by ASB.

WRITTEN: Adam S. Bolton, U of Utah, 2009