This module sets up a 1D density perturbation and then checks the final value with the analytic value.  It is designed to run on only one processor in fixed grid and is useful for checking the order of schemes.  It produces a data.curve file which has the grid solution and the exact solution.  It also prints out the resolution and the error at the end of the run.  By adjusting the resolution from 50, 100, 200, and 400 and plotting the error, the order of the method can be determined.