text: #include <stdio.h>
  #include <stdlib.h>
  #include <math.h>
  
  float distancef(float lon1, float lat1, float lon2, float lat2)
  {
  	float x;
  	x = sqrt((lon1-lon2)*(lon1-lon2)+(lat1-lat2)*(lat1-lat2));
  	return x;
  }
  
  