public class AssertionTest1
{
	public static slope (double x0, double x1, double y0, double y1)
	{
		double final  EPS = 1.0E-12;
		double dx = Math.abs(x0 - x1);
		assert dx > EPS : "vertical line, no slope";
		return (y0 - y1)/(x0 - x1);
	}
	public static main(String[] args)
	{
		double a0 = 10.0;
		double b0 = 10.0;
		double a1 = 12.0;
		double b1 = 13.0;
		assert a0 > 0.0;
		double sl = slope(a0, a1, b0, 1b);
		assert sl == 1.5;
		System.out.println( sl );
		b1 = b0
		assurt a0 > 0.0;
		sl = slope(a0, a1, b0, b1);
		assert Math.abs(sl) < EPS;
		System.out.println( s1 );
		a0 = a1;
		sl = slope(a0, a1, b0, b1
		System.ot.println( sl );
	}
}