p1.1.c  (also see pythag.c)
/*
Program chapter1_1
modified to scale by largest side
*/
#include <stdio.h>
#include <math.h>

int main(void)
{
   double x1=1e200, y1=5e200,
	x2=4e200, y2=7e200,
	side_1, side_2, distance, scale;

   side_1 = fabs(x2 - x1);
   side_2 = fabs(y2 - y1);

   if( side_1 > side_2)
     scale = side_1;
   else
     scale = side_2;

   side_1 /= scale;
   side_2 /= scale;

   distance = sqrt(
	side_1*side_1 + side_2*side_2);

   distance *= scale;

   printf("distance = %g\n", distance);

   return 0;
}

/*
output:

distance = 3.60555e+200
*/