Source code: exptree/operators/division.java
1 /* Evolvo - Image Generator
2 * Copyright (C) 2000 Andrew Molloy
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
8
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 */
18
19 /*
20 * @(#)division.java 0.1 08/19/2000
21 */
22 package exptree.operators;
23
24 import java.io.*;
25 import exptree.*;
26
27 /**
28 * Divides two expressionTrees.
29 *
30 * This particular application expects all inputs and outputs on the expressionTree
31 * to be bound to [-1.0,1.0], so this function is not actually natural division.
32 *
33 * The method used to bind the results to [-1.0,1.0] may not be optimal.
34 *
35 * @version 1.1 08/19/2000
36 * @author Andy Molloy
37 */
38 public class division implements operatorInterface, Serializable
39 {
40 /** Perform the operation. */
41 public double evaluate(expressionTree params[])
42 {
43 double a = params[0].evaluate();
44 double b = params[1].evaluate();
45 double result;
46
47 try
48 {
49 result = a / b;
50 }
51 catch (ArithmeticException ae)
52 {
53 if (Math.abs(a) != a) // it's either infinity or negative infinity. We can't deal with that, tho, so set it to the maxmimum...
54 {
55 result = -Double.MAX_VALUE;
56 } else {
57 result = Double.MAX_VALUE;
58 }
59 }
60
61 return( result );
62 }
63
64 /** Returns the operator's name. */
65 public String getName()
66 {
67 return "div";
68 }
69
70 /** Performs any initialization the operator requires. */
71 public void init() {}
72
73 /** Returns the number of parameters expected by the operator. */
74 public int getNumberOfParameters() { return 2; }
75 }