Constructing an interpolation table

To construct an interpolation table, use the do_interpolation.py python script with a configuration file.

python scripts/do_interpolation.py -f /path/to/config_file.json -s /path/to/output/directory -im

Example configuration files can be found in the interpolation_settings/ directory in the git repository.

Option	flag	Description
--input-file	-f	Path to configuration file.
--save-dir	-s	Path to directory for saving the interpolation tables.
--image	-im	Also construct an interpolation table for the image magnifications and time delays, in addition to the amplification factor.
--skip-strong	-ss	Skip the strong lensing region in the parameter space.
--skip-weak	-sw	Skip the weak lensing region in the parameter space.
--skip-amplification	-sa	Skip the computation of the amplification factor.

The configuration file should be in json format with the following entries:

Parameter	Type	Description
lens_param_name	str	Name given to the lens parameter \(l\), e.g. kappa for the NFW lens or x_c for the CIS lens.
y_low	float	Lower limit of the impact parameter \(y\) in the interpolation domain.
y_high	float	Upper limit of the impact parameter \(y\) in the interpolation domain.
lp_low	float	Lower limit of the lens parameter \(l\) in the interpolation domain.
lp_high	float	Upper limit of the lens parameter \(l\) in the interpolation domain.
N_grid	int	Number of interpolation nodes to use in each dimension on the \(y\)-\(l\) plane to use for the weak lensing region.
N_grid_strong	int	Number of interpolation nodes to use in each dimension on the \(y\)-\(l\) plane to use for the strong lensing region.
N_crit	int	Number of interpolation nodes on the caustic curve.
N	int	Number of interpolation nodes in dimensionless time \(\tau\) to use in each section of the time domain amplification factor.
lens_model_name	str	The name of the lens model, e.g. NFW.
crit_lp_N	int	Number of points in \(l\) to use for a high-resolution interpolator tracing out the caustic curve in the \(y\)-\(l\) plane.
im_x_init_low	float	Lower limit of the im_x_init array of initial guesses for Newton's method when solving for image positions.
im_x_init_high	float	Upper limit of the im_x_init array of initial guesses for Newton's method when solving for image positions.
im_x_init_num	int	Number of points in the im_x_init array of initial guesses for Newton's method when solving for image positions.
lp_low_im	float	Lower limit of the lens parameter \(l\) in the interpolation domain for image related quantities.
lp_high_im	float	Upper limit of the lens parameter \(l\) in the interpolation domain for image related quantities.
N_grid_im	int	Number of interpolation nodes to use in each dimension on the \(y\)-\(l\) plane to use for interpolating image related quantities.
N_crit_im	int	Number of interpolation nodes to use on the caustic curve for interpolating image related quantities.
newt_max_iter_im	int	Maximum iterations for Newton's method when solving for the image positions.
crit_lp_im	int	Number of points in \(l\) to use for a high-resolution interpolator tracing out the caustic curve in the \(y\)-\(l\) plane, for calculations related to the images.