this is a self-contained tool to visualize gravity waves extracted from numerical relativity simulations
it processes output from NR simulation into either 2D or 3D .vtk data which can then be visualized using VisIt
for the cpp code to work, the fftw package is needed, see 'install_fftw.txt' for instructions

the input is the Weyl curvature component Psi4
 - the script 'bin/calc_clm.cpp' script more or less follows the frequency domain integration talked about in arXiv:1006.1632
 - the files that this code is built to read have columns (the last three columns aren't used by the code but are output by the simulations we use)
       time | (2,2)_real | (2,2)_imag | (2,1)_real | (2,1)_imag | (2,0)_real ....... | ('last_mode')_imag | r_areal | Averaged g^tt | Averaged g^tr | Averaged g^rr


USE: 
Step 1, set parameters in 'params_gw.py'

Step 2, in 'setup_gw.py', specify the name of the output folder and run it; it does the following things
 - this Psi4 file is cleaned and then in 'calc_clm.cpp', the 'Psi4_lm's are processed into 'C_lm's which is the strain h decomposed into s=-2 spherical harmonics
 - rather inefficient python code 'hplus_hcross.py' takes the 'C_lm's and generates 2D or 3D data that adds the 1/r falloff, time retardation t -> t - r

Step 3, in 'runGW.sh', specify some run parameters and run it;
 - this script is designed to use sbatch