/*
 * Computing machine epsilon.  On Linux/i386 with 
 *
 *   gcc version 2.96 20000731 (Red Hat Linux 7.3 2.96-113)
 *
 * these give 1.0842e-19 with -O1, -O2, and -O3, and 2.22045e-16 with -O0
*/

#include <stdio.h>

#ifdef USE_STORE

#define ONE store[0]
#define EPS store[1]
#define NEWEPS store[2]
#define ONE_PLUS_NEWEPS store[3]

double store[4];

int main()
{
    ONE = 1.0;
    EPS = 1.0;

    NEWEPS = EPS / 2.0;
    ONE_PLUS_NEWEPS = ONE + NEWEPS;
    while (ONE_PLUS_NEWEPS != ONE) {
	EPS = NEWEPS;
	NEWEPS = EPS / 2.0;
	ONE_PLUS_NEWEPS = ONE + NEWEPS;
    }

    printf("Epsilon = %g\n", EPS);

    return 0;
}
#else
int main()
{
    double one = 1.0;
    double eps = 1.0;
    double neweps, one_plus_neweps;

    neweps = eps / 2.0;
    one_plus_neweps = one + neweps;
    while (one_plus_neweps != one) {
	eps = neweps;
	neweps = eps / 2.0;
	one_plus_neweps = one + neweps;
    }

    printf("epsilon = %g\n", eps);

    return 0;
}

#endif