Parameter File: par_ahf.d

Apparent Horizon Finder Parameters.

This file controls the behavior of the apparent horizon finder (AHF).

The parameters must be listed in this specific order, as the code reads them sequentially using fscanf. Lines starting with # are ignored as comments.

1. AHFstart 

Physical time at which to start searching for apparent horizons.

Data Type:

Double (double)

Note

Read using lf. Corresponds to AHFstart in main.

1. ahcint 

Interval (in number of main simulation time steps) between calls to the AHF.

Data Type:

Integer (int)

Note

Read using d. The AHF is called when step % ahcint == 0. Corresponds to ahcint in main.

1. ahpint 

Interval (in number of AHF calls) between printing detailed horizon shape/data to out_AHfig.dat.

Data Type:

Integer (int)

Note

Read using d. Output occurs when (step / ahcint) % ahpint == 0. Corresponds to ahpint in main.

1. ntheta 

Number of grid points in the theta (polar angle) direction for the AHF's internal spherical grid. Total points used is ntheta + 2.

Data Type:

Integer (int)

Note

Read using d. Corresponds to ntheta in main and Ahf2d constructor.

1. nphi 

Number of grid points in the phi (azimuthal angle) direction for the AHF's internal spherical grid. Total points used is nphi + 2.

Data Type:

Integer (int)

Note

Read using d. Corresponds to nphi in main and Ahf2d constructor.

1. ahloop 

Maximum number of iterations allowed for the AHF solver (Poisson and AH equation) to converge in a single call.

Data Type:

Integer (int)

Note

Read using d. Corresponds to ahloop in main.

1. etaah 

Acceleration parameter eta for the AHF elliptic solver (IMLUCGS method, see PRD 55, 2002 (1997)). Also used to distinguish AH (eta=1) from CH (eta=3).

Data Type:

Double (double)

Note

Read using lf. Corresponds to var in ahf_read and Ahf2d::var.

1. facn 

Mixing factor for updating the horizon radius guess during iterations (h_new = fac*h_solved + (1-fac)*h_old).

Data Type:

Double (double)

Note

Read using lf. Corresponds to facn in ahf_read and Ahf2d::fac.

1. err_p 

Relative error tolerance for the Poisson solver part of the AHF.

Data Type:

Double (double, exponential notation)

Note

Read using le. Corresponds to err_p in ahf_read.

1. err_e 

Relative error tolerance for the main apparent horizon equation solver.

Data Type:

Double (double, exponential notation)

Note

Read using le. Corresponds to err_e in ahf_read.

1. ahc 

Initial guess for the apparent horizon radius (coordinate radius). Used when the AHF starts or resets.

Data Type:

Double (double)

Note

Read using lf. Corresponds to ahc in ahf_read and Ahf2d::hini.