#include
#include
const double R=6378.1370;
const double pi=3.141592654;
double chord_len(double a,double b);
double arc_len(double a,double b);
double chord_len(double a,double b)
{
double x,rad;
/*printf("%f,%f in chord_len\n",a,b);*/
rad=fabs(b-a);
if ( rad > 180) rad = 360-rad;
rad = rad*pi/180;
x=sqrt(2.0)*R*sqrt(1.0-cos(rad));
return x;
}
double arc_len(double a,double b)
{
double x,rad;
rad=fabs(b-a);
if ( rad > 180) rad = 360-rad;
x=R*rad*pi/180;
return x;
}
int main()
{
double a,b;
printf("請(qǐng)輸入兩個(gè)城市的經(jīng)度（以空格隔開.東經(jīng)為正,西經(jīng)為負(fù).）:\n");
scanf("%lf %lf",&a,&b);
printf("%lf,%lf\n",a,b);
printf("兩個(gè)城市的直線距離為:%f\n",chord_len(a,b));
printf("兩個(gè)城市的球面距離為:%f\n",arc_len(a,b));
return 0;
}