for(i=1;i<=NDIM;i++) {
      for(j=1;j<=NDIM;j++) { /* temporary IC for Efimov stimulation: */ 
         u[i][j] = uo 
                   +4* exp( -( pow((0.5-space)*NDIM-i,2) +pow(0.5*NDIM-j,2) ) /pow(size*(NDIM-1),2)  )  
                   -4* exp( -( pow((0.5+space)*NDIM-i,2) +pow(0.5*NDIM-j,2) ) /pow(size*(NDIM-1),2)  );
         v[i][j] =  vo + magv*(u[i][j]-uo); 
   break;} /* for FitzHugh-Nagumo medium: superposed conical Gaussian +,- offsets near middle of box */

u = scaled membrane potential;  uo = -1.2 (the rest potential)
v = scaled refractoriness; vo = -0.6 (fully recovered)
NDIM=60 gridpoints about 1 mm apart along the square box edge representing around 6-10 cm
size = 0.10 scales the abruptness of Gaussian tapering of u,v offsets with radius from electrodes
space = 0.03 (3% of box width between each electrode and the midline thus about 1/2 cm between electrodes)