#include "fdtd3.h"static int temporalStride=0, spatialStride, startTime,  startNode, endNode, frame=0;static char basename[80];void snapshotInit(Grid *g) {     printf("For the snapshots:\n");  printf("  Duration of simulation is %d steps.\n",MaxTime);  printf("  Enter start time and temporal stride: ");  scanf(" %d %d",&startTime,&temporalStride);  printf("  Grid has %d total nodes (ranging from 0 to %d).\n",	 SizeX,SizeX-1);  printf("  Enter first node, last node, and spatial stride: ");  scanf(" %d %d %d",&startNode,&endNode,&spatialStride);  printf("  Enter the base name: ");  scanf(" %s",basename);  return;}void snapshot(Grid *g) {   int mm;  char filename[100];  FILE *snapshot;  /* ensure temporal stride set to a reasonable value */  if (temporalStride<=0) {    fprintf(stderr,      "snapshot: snapshotInit must be called before snapshot.\n"      "          Temporal stride must be set to positive value.\n");    exit(-1);  }  /* get snapshot if temporal conditions met */  if (Time>=startTime &&       (Time-startTime)%temporalStride == 0) {    sprintf(filename,"%s.%d",basename,frame++);    snapshot=fopen(filename,"w");    for (mm=startNode; mm <= endNode; mm+=spatialStride)      fprintf(snapshot,"%g\n",Ez(mm));    fclose(snapshot);  }  return;}