*--------------------------------------------------------------------*
*   common definitions for XYfdtd.f                                  *
*--------------------------------------------------------------------*
*
*  define some fundemental constants
*  c=speed of light in vacuum, pi, eps0=permittivity of free space
*  xmu0=permeability of free space
*
      parameter(c=2.99795e8,pi=3.14159265,eps0=8.854e-12,
     >          xmu0=1.25663706e-6)
*
*  mesh dimensions
*
      parameter(nx=256,ny=256)
      parameter(nx1=nx-1,ny1=ny-1)
      character*5 wave
*
*  array definitions for a simple wave propagation study
*
      real ezs(nx,ny),ezs1(nx,ny),ezs2(nx,ny),
     >     hxs(nx,ny),hys(nx,ny)
      integer imet(nx,ny)
      common/escat/ezs,imet
      common/esave/ezs1,ezs2
      common/hscat/hxs,hys
      common/wtype/wave
      common/stuff/t,dt,ds,dte,dtm,dteds,dtmds,dtsi,nstart,
     >             nstop,idata,c1,c2,c3,c4,imid,jmid,
     >             iplot,emax,emin,nst,nen,mst,men