So I have a 1-D FDTD simulation and I'm trying to implement periodic boundaries. I currently have two problems.

1. The signal isn't cleanly transmitted. What goes in as a Gaussian comes out looking something like a sine wave. The code I used for my update equations is:

static double  imp0 = 377.0;

/* update H field */

void updateH3(Grid *g){

        int mm;

        for (mm = 0; mm