// This code shows that floating-point arithmetic has limited precision.
// Just as one-third can’t be represented exactly as a finite decimal
// number, 0.1 can’t be represented exactly as a finite binary number.

#include <stdio.h>
#include <math.h>

int main() {
    double a=0.1, b=0.2;

    if (a+b == 0.3)
	puts("Absolutely equal!");
    else
	puts("Unequal--huh?");

    // OK, fine, we can’t ask if they’re exactly the same.
    // How about if we ask if they’re close enough?

    double difference = fabs(a+b - 0.3);
    if (difference < 1e-12)
	puts("Close enough for engineering");
    else
	puts("Not very close");

    return 0;
}

// Why did I use the absolute value?
// Why did I use fabs, rather than just abs?