From 95393e7d4f71581fc8eb71745170799a1beea376 Mon Sep 17 00:00:00 2001 From: jthorn Date: Tue, 8 Feb 2005 10:36:11 +0000 Subject: better describe how this thorn actually works git-svn-id: http://svn.einsteintoolkit.org/cactus/EinsteinInitialData/Exact/trunk@217 e296648e-0e4f-0410-bd07-d597d9acff87 --- src/README | 46 +++++++++++++++++++++++++++++++--------------- 1 file changed, 31 insertions(+), 15 deletions(-) (limited to 'src') diff --git a/src/README b/src/README index 8631ce8..c577c5b 100644 --- a/src/README +++ b/src/README @@ -29,28 +29,44 @@ decode_pars.F77 #defined in include/param_defs.inc ). initialize.F77 - This is the main top-level routine scheduled at INITIAL - to set up an initial slice. + This contains the subroutine Exact__initialize(), which is + top-level routine scheduled at INITIAL to set up an initial + slice. This basically just calls Exact__Bona_Masso_data() + at each grid point, discarding everything it computes other + than the 3-metric, the extrinsic curvature, and possibly + the conformal factor and its spatial derivatives. + +gauge.F77 + This contains code to set the lapse/shift from an exact solution + either on the initial slice, or at each time step of an evolution. + This works by calling Exact__Bona_Masso_data() at each grid + point, discarding everything it computes except the lapse and + the shift. Bona_Masso_data.F77 - This contains code to compute the Bona-Masso variables for - the initial data, making use of the subroutine Exact__metric() - to calculate the spacetime metric and its inverse. Note that - this use of the Bona-Masso variables is independent of how - (or even if) we are evolving the Einstein equations -- here - the Bona-Masso variables are "just" used as intermediate variables. + This contains the subroutine Exact__Bona_Masso_data(), + which computes the ADM variables (3-metric, extrinsic curvature, + lapse, shift) and some of their spatial derivatives + (1st derivatives of the 3-metric and the lapse, + 2nd derivatives of the conformal factor and the shift vector) + by calling Exact__metric() and finite differencing. + [using a hard-coded 1.0e-6 grid spacing :( ] + Note that despite the name and comments referring to the + Bona-Masso variables, this subroutine doesn't appear to + actually use the Bona-Masso variables (!). + +boost.F77 + This contains the subroutine Exact__metric(), which calls + Exact__metric_for_model() and then applies an optional + Lorentz boost to the resulting 4-metric and its inverse. metric.F77 - This contains the subroutine Exact__metric(); this decodes - the decoded_exact_model parameter and calls the appropriate - Exact__model_name_coords() subroutine to compute the 4-metric + This contains the subroutine Exact__metric_for_model(); this + decodes the decoded_exact_model parameter and calls the appropriate + Exact___() subroutine to compute the 4-metric and its inverse at a point. See the metrics/ subdirectory for these computations for the various models. -gauge.F77 - This contains code to set the lapse/shift from an exact solution - at each time step of an evolution. - boundary.F77 This is the top-level routine scheduled at POSTSTEP to implement exact-solution boundary conditions. -- cgit v1.2.3