The .pro files here constitute the code for the BOUT++ line tracing utility
written in IDL. This utility must be run from within the IDL environment.

First make sure that you specify the location of these files in your IDL path
environment variable. This can be done by adding the following line to your
.IDL_STARTUP file or just executing directly in IDL:
  !path=!path+":/LOCATION/OF/THIS/DIRECTORY"

A sample IDL_STARTUP file is included in MISC for reference. Paths will need to
be changed.

Then just execute the code using a command of the form:
  poincare,tindex=10,nstart=50,nmap=100,method='bicube_fft'

This assumes that IDL is in the root simulation directory and the directory
structure is of the form:
  elm_pb/
        /data/
             /grid_file.nc
             /BOUT.dmp.*.nc

This will generate an IDL data file "poincare.10.bicube_fft.idl.dat" in the 
directory "data". This can be read in again and plotted using the command:
  poincare,s_file='poincare.10.bicube_fft.idl.dat'

The options that can be specified at run-time are described at the start of the
poincare.pro file. Hopefully the rest of the code should be commented well-
enough to give an idea of what is going on.

misc:
  apar_*.pro - files evaluate derivatives of vector potential at given (x,y,z)
  mc_*.pro   - evaluates metric coefficients at given (x,y,z)
  cp_*.pro   - converts the data to a form more amenable to direct indexing
               (i.e. duplicating data apar[*,*,0] in apar[*,*,NZ])

-JPS (8/24/2011)
