lenstronomy.LensModel.Solver package

Submodules

lenstronomy.LensModel.Solver.lens_equation_solver module

class lenstronomy.LensModel.Solver.lens_equation_solver.LensEquationSolver(lensModel)[source]

Bases: object

class to solve for image positions given lens model and source position

candidate_solutions(sourcePos_x, sourcePos_y, kwargs_lens, min_distance=0.1, search_window=10, verbose=False, x_center=0, y_center=0)[source]

finds pixels in the image plane possibly hosting a solution of the lens equation, for the given source position and lens model

Parameters:
  • sourcePos_x – source position in units of angle
  • sourcePos_y – source position in units of angle
  • kwargs_lens – lens model parameters as keyword arguments
  • min_distance – minimum separation to consider for two images in units of angle
  • search_window – window size to be considered by the solver. Will not find image position outside this window
  • verbose – bool, if True, prints some useful information for the user
  • x_center – float, center of the window to search for point sources
  • y_center – float, center of the window to search for point sources
Returns:

(approximate) angular position of (multiple) images ra_pos, dec_pos in units of angles, related ray-traced source displacements and pixel width

Raises:

AttributeError, KeyError

findBrightImage(sourcePos_x, sourcePos_y, kwargs_lens, numImages=4, min_distance=0.01, search_window=5, precision_limit=1e-10, num_iter_max=10, arrival_time_sort=True, x_center=0, y_center=0, num_random=0, non_linear=False, magnification_limit=None, initial_guess_cut=True, verbose=False)[source]
Parameters:
  • sourcePos_x – source position in units of angle
  • sourcePos_y – source position in units of angle
  • kwargs_lens – lens model parameters as keyword arguments
  • min_distance – minimum separation to consider for two images in units of angle
  • search_window – window size to be considered by the solver. Will not find image position outside this window
  • precision_limit – required precision in the lens equation solver (in units of angle in the source plane).
  • num_iter_max – maximum iteration of lens-source mapping conducted by solver to match the required precision
  • arrival_time_sort – bool, if True, sorts image position in arrival time (first arrival photon first listed)
  • initial_guess_cut – bool, if True, cuts initial local minima selected by the grid search based on distance criteria from the source position
  • verbose – bool, if True, prints some useful information for the user
  • x_center – float, center of the window to search for point sources
  • y_center – float, center of the window to search for point sources
  • num_random – int, number of random positions within the search window to be added to be starting positions for the gradient decent solver
  • non_linear – bool, if True applies a non-linear solver not dependent on Hessian computation
  • magnification_limit – None or float, if set will only return image positions that have an abs(magnification) larger than this number
Returns:

(exact) angular position of (multiple) images ra_pos, dec_pos in units of angle

image_position_from_source(sourcePos_x, sourcePos_y, kwargs_lens, min_distance=0.1, search_window=10, precision_limit=1e-10, num_iter_max=100, arrival_time_sort=True, initial_guess_cut=True, verbose=False, x_center=0, y_center=0, num_random=0, non_linear=False, magnification_limit=None)[source]

finds image position source position and lens model

Parameters:
  • sourcePos_x – source position in units of angle
  • sourcePos_y – source position in units of angle
  • kwargs_lens – lens model parameters as keyword arguments
  • min_distance – minimum separation to consider for two images in units of angle
  • search_window – window size to be considered by the solver. Will not find image position outside this window
  • precision_limit – required precision in the lens equation solver (in units of angle in the source plane).
  • num_iter_max – maximum iteration of lens-source mapping conducted by solver to match the required precision
  • arrival_time_sort – bool, if True, sorts image position in arrival time (first arrival photon first listed)
  • initial_guess_cut – bool, if True, cuts initial local minima selected by the grid search based on distance criteria from the source position
  • verbose – bool, if True, prints some useful information for the user
  • x_center – float, center of the window to search for point sources
  • y_center – float, center of the window to search for point sources
  • num_random – int, number of random positions within the search window to be added to be starting positions for the gradient decent solver
  • non_linear – bool, if True applies a non-linear solver not dependent on Hessian computation
  • magnification_limit – None or float, if set will only return image positions that have an abs(magnification) larger than this number
Returns:

(exact) angular position of (multiple) images ra_pos, dec_pos in units of angle

Raises:

AttributeError, KeyError

image_position_stochastic(source_x, source_y, kwargs_lens, search_window=10, precision_limit=1e-10, arrival_time_sort=True, x_center=0, y_center=0, num_random=1000)[source]

Solves the lens equation stochastic with the scipy minimization routine on the quadratic distance between the backwards ray-shooted proposed image position and the source position. Credits to Giulia Pagano

Parameters:
  • source_x – source position
  • source_y – source position
  • kwargs_lens – lens model list of keyword arguments
  • search_window – angular size of search window
  • precision_limit – limit required on the precision in the source plane
  • arrival_time_sort – bool, if True sorts according to arrival time
  • x_center – center of search window
  • y_center – center of search window
  • num_random – number of random starting points of the non-linear solver in the search window
Returns:

x_image, y_image

sort_arrival_times(x_mins, y_mins, kwargs_lens)[source]

sort arrival times (fermat potential) of image positions in increasing order of light travel time

Parameters:
  • x_mins – ra position of images
  • y_mins – dec position of images
  • kwargs_lens – keyword arguments of lens model
Returns:

sorted lists of x_mins and y_mins

lenstronomy.LensModel.Solver.solver module

class lenstronomy.LensModel.Solver.solver.Solver(solver_type, lensModel, num_images)[source]

Bases: object

joint solve class to manage with type of solver to be executed and checks whether the requirements are fulfilled.

add_fixed_lens(kwargs_fixed_lens, kwargs_lens_init)[source]

returns kwargs that are kept fixed during run, depending on options

Parameters:
  • kwargs_fixed_lens – keyword argument list of fixed parameters (indicated by fitting argument of the user)
  • kwargs_lens_init – Initial values of the full lens model keyword arguments
Returns:

updated kwargs_fixed_lens, added fixed parameters being added (and replaced later on) by the non-linear solver.

check_solver(image_x, image_y, kwargs_lens)[source]

returns the precision of the solver to match the image position

Parameters:
  • kwargs_lens – full lens model (including solved parameters)
  • image_x – point source in image
  • image_y – point source in image
Returns:

precision of Euclidean distances between the different rays arriving at the image positions

constraint_lensmodel(x_pos, y_pos, kwargs_list, xtol=1.49012e-12)[source]
Parameters:
  • x_pos
  • y_pos
  • kwargs_list
Returns:

update_solver(kwargs_lens, x_pos, y_pos)[source]
Parameters:
  • kwargs_lens
  • x_pos
  • y_pos
Returns:

lenstronomy.LensModel.Solver.solver2point module

class lenstronomy.LensModel.Solver.solver2point.Solver2Point(lensModel, solver_type='CENTER', decoupling=True)[source]

Bases: object

class to solve a constraint lens model with two point source positions

options are: ‘CENTER’: solves for ‘center_x’, ‘center_y’ parameters of the first lens model ‘ELLIPSE’: solves for ‘e1’, ‘e2’ of the first lens (can also be shear) ‘SHAPELETS’: solves for shapelet coefficients c01, c10 ‘THETA_E_PHI: solves for Einstein radius of first lens model and shear angle of second model

add_fixed_lens(kwargs_fixed_lens_list, kwargs_lens_init)[source]
Parameters:
  • kwargs_fixed_lens_list
  • kwargs_lens_init
Returns:

constraint_lensmodel(x_pos, y_pos, kwargs_list, xtol=1.49012e-12)[source]

constrains lens model parameters by demanding the solution to match the image positions to a single source position

Parameters:
  • x_pos – list of image positions (x-axis)
  • y_pos – list of image position (y-axis)
  • kwargs_list – list of lens model kwargs
  • xtol – tolerance level of solution when to stop the non-linear solver
Returns:

updated lens model that satisfies the lens equation for the point sources

solve(x_pos, y_pos, init, kwargs_list, a, xtol=1.49012e-12)[source]

lenstronomy.LensModel.Solver.solver4point module

class lenstronomy.LensModel.Solver.solver4point.Solver4Point(lensModel, solver_type='PROFILE')[source]

Bases: object

class to make the constraints for the solver

add_fixed_lens(kwargs_fixed_lens_list, kwargs_lens_init)[source]
Parameters:
  • kwargs_fixed_lens_list
  • kwargs_lens_init
Returns:

constraint_lensmodel(x_pos, y_pos, kwargs_list, xtol=1.49012e-12)[source]
Parameters:
  • x_pos – list of image positions (x-axis)
  • y_pos – list of image position (y-axis)
  • init – initial parameters
  • kwargs_list – list of lens model kwargs
Returns:

updated lens model that satisfies the lens equation for the point sources

solve(x_pos, y_pos, init, kwargs_list, a, xtol=1.49012e-10)[source]

Module contents