[Users] SubstepOutput

[Ian Hinder]

Hi all,

I have a small thorn which might be useful for debugging.  It enables output of grid variables on each MoL substep, so you can see what is happening on each one.  The variables are output into files with the substep number appended, so you get, for example,

	phi.x.asc
	phi_0.x.asc
	phi_1.x.asc
	phi_2.x.asc

for a 3-step method (e.g. RK3).  The first step is 0 (in contrast to how MoL counts internally, which is backwards).

This happens

	in MoL_Step after MoL_RHSBoundaries before MoL_NaNCheck

which should be sufficient.  You could also manually modify the schedule to investigate at other points, if that is useful to you.

You use the thorn by setting the parameter SubstepOutput::vars to the list of variables or groups you want to output, for example

	SubstepOutput::vars = "Wave::phi Wave::pi Wave::phirhs Wave::pirhs"

You can also set the output method to use:

	SubstepOutput::output_method = "IOHDF5"

It defaults to IOASCII_1D.  

You can get this thorn using

	git clone https://bitbucket.org/ianhinder/substepoutput.git SubstepOutput

It might be appropriate for this functionality to be implemented in MoL instead.

-- 
Ian Hinder
http://numrel.aei.mpg.de/people/hinder