//p24.c -- @CopyLeft by tsaiwn@csie.nctu.edu.tw
// demo the precision of double in C Language
// double 實數準確度約十五位多
#include<stdio.h>
double x, xdelta; int i;   /*precdbl.c */
main( ) { double y;
    x = 1234567.2,  xdelta = 0.0001;
    printf("Before loop, x=%f\n", x);
    for(i=1; i<= 8000; i++){
        y = x + xdelta;     /******/
        if(i == 1) printf("first y = %f\n", y);
        x = y;
   }
   printf("After loop, x=%f\n", x);
   printf("Hit RETURN key...");
   getchar( );
   return 0;
}  //main(
/******
ccbsd2:precision/> gcc precdbl.c
ccbsd2:precision/> ./a.out
Before loop, x=1234567.200000
first y = 1234567.200100
After loop, x=1234568.000001
ccbsd2:precision/> 
       ****** double 實數佔用 64 bits
====== run on Windows ======

C:\test2>gcc p24.c

C:\test2>a.exe
Before loop, x=1234567.200000
first y = 1234567.200100
After loop, x=1234568.000001

C:\test2>

*************************/