CIS 3020 Project 2 - Revision history

Jka: /* RationalNumberDemo.java */

2007-03-30T14:53:49Z

RationalNumberDemo.java

Jka: /* Division */

2007-03-30T14:53:11Z

Division

Show changes

Jka at 14:51, 30 March 2007

2007-03-30T14:51:49Z

New page

==Background==
In this assignment you will perform basic arithmetic operations with rational numbers (x/y).
Many fractional numbers cannot be represented exactly. For example, the value 1/3 as a real
number is 0.333333333... At some point we must stop writing 3s, which results in a roundoff
error. A similar problem exists with many fraction numbers inside a computer. To alleviate this
problem, we can represent these numbers as rationals. A rational number maintains the
numerator and denominator as separate integer values, never performing the division. Since
integers are represented exactly, no roundoff errors occur.

In this assignment you are to implement the basic arithmetic operations of addition, subtraction,
multiplication, and division. The output of the operations must also be in the form of a rational
number. The operations are performed as illustrated below:
===Addition===
<pre>
x1 x2 (x1*y2) + (x2*y1)
---- + ---- = -------------------
y1 y2 (y1*y2)
</pre>
For example:
<pre>
1/2 + 2/3 = 7/6
</pre>
===Subtraction===
<pre>
x1 x2 (x1*y2) - (x2*y1)
---- - ---- = ------------------
y1 y2 (y1*y2)
</pre>
For example:
<pre>
2/3 - 1/2 = 1/6
</pre>
===Multiplication===
<pre>
x1 x2 (x1*x2)
---- * ---- = ---------
y1 y2 (y1*y2)
</pre>
For example:
<pre>
1/2 * 2/3 = 2/6
</pre>
===Division===
<pre>
x1 x2 (x1*y2)
---- / ---- = ---------
y1 y2 (y1*x2)
</pre>
For example:
<pre>
1/2 / 2/3 = 3/4
</pre>

← Older revision		Revision as of 14:53, 30 March 2007
Line 318:		Line 318:
	</pre>		</pre>
	==RationalNumberDemo.java==		==RationalNumberDemo.java==
		+	<pre>
		+	public class RationalNumberDemo extends RationalNumber {
		+	public static void main(String[] arg) {
		+	/* The first thing we need to do is create our two objects. We do that
		+	by first creating the two new objects, then setting the rational
		+	numbers that they represent.
		+	*/
		+	RationalNumber ratNum1 = new RationalNumber();
		+	RationalNumber ratNum2 = new RationalNumber();
		+	// Now set the first one's value. Note that this is where we would
		+	// set all of the values needed. This is the ONLY place we need to
		+	// set them!
		+	ratNum1.setNumerator(2);
		+	ratNum1.setDenominator(5);
		+	// And the second one's...
		+	ratNum2.setNumerator(1);
		+	ratNum2.setDenominator(7);
		+	//
		+	// Now we need to go and see that these two numbers really were
		+	// put in properly...
		+	//
		+	System.out.printf("Rational Number 1, rn1, has been defined to be: %s\n",
		+	ratNum1.toString());
		+	System.out.printf("Rational Number 2, rn2, has been defined to be: %s\n",
		+	ratNum2.toString());
		+	/* Now we need to print out the different variations of the operations
		+	that can be performed on these two rational numbers. Because we have
		+	defined them above, we are not going to type in those numbers again
		+	here. By defining them up there, we can now just call on those
		+	definitions from now on and not have to worry about changing them in
		+	more than the one place above.
		+
		+	In the future, we would probably have them either input by the user
		+	from the command line or pop up an input box for them to be entered
		+	into, thus making them more dynamic. As it is, it is very easy to
		+	take the RationalNumber class and use it in such a front end.
		+	*/
		+
		+	// Add the second one to the first one
		+	System.out.printf("%s + %s = %s\n", ratNum1.toString(),
		+	ratNum2.toString(), ratNum1.perform("add", ratNum2));
		+	// Subtract the second one from the first one
		+	System.out.printf("%s - %s = %s\n", ratNum1.toString(), ratNum2.toString(),
		+	ratNum1.perform("sub", ratNum2));
		+	// Subtract the first one from the second one
		+	System.out.printf("%s - %s = %s\n", ratNum2.toString(), ratNum1.toString(),
		+	ratNum2.perform("sub", ratNum1));
		+	// Multiply the first one by the second one
		+	System.out.printf("%s * %s = %s\n", ratNum1.toString(), ratNum2.toString(),
		+	ratNum1.perform("mult", ratNum2));
		+	// Divide the first one by the second one
		+	System.out.printf("%s / %s = %s\n", ratNum1.toString(), ratNum2.toString(),
		+	ratNum1.perform("div", ratNum2));
		+	// Divide the second one by the first one
		+	System.out.printf("%s / %s = %s\n", ratNum2.toString(), ratNum1.toString(),
		+	ratNum2.perform("div", ratNum1));
		+	} // End main
		+	} // End RationalNumberDemo Class
		+	</pre>