1    /* 
2     * Created by IntelliJ IDEA. 
3     * User: lyon 
4     * Date: Feb 15, 2003 
5     * Time: 1:22:04 PM 
6     */ 
7    package math; 
8     
9    import futils.WriterUtil; 
10    
11   import java.awt.*; 
12    
13   public class MathUtils { 
14       public static int getRandom() { 
15           return (int) ((Math.random() * 100) + 1); 
16       } 
17    
18       public static void main(String args[]) { 
19           writeOutRandomNumbersToAFile(); 
20       } 
21    
22       public static void writeOutRandomNumbersToAFile() { 
23           int ia[] = new int[100]; 
24           for (int i = 0; i < ia.length; i++) 
25               ia[i] = rand(1, 100); 
26           WriterUtil.writeString( 
27                   WriterUtil.getCSVString(ia)); 
28       } 
29    
30       public static void randTest() { 
31           for (int i = 0; i < 100; i++) { 
32               System.out.print(rand(1, 10) + " "); 
33               if (i % 20 == 0) System.out.println(); 
34           } 
35       } 
36    
37       /** 
38        * Compute a random integer 
39        * @param min  minimum int 
40        * @param max  maximum int 
41        * @return random int between <code>min</code> and 
42        * <code>max</code> inclusive. 
43        */ 
44       public static int rand(int min, int max) { 
45           return (int) (Math.round( 
46                   Math.random() * (max - min) + min)); 
47       } 
48       public static Color getRandomColor() { 
49           return new Color(rand(0,255),rand(0,255),rand(0,255)); 
50       } 
51    
52       public static boolean odd(int i) { 
53           if ((i & 1) == 1) return true; 
54           return false; 
55       } 
56    
57       /** 
58        * 
59        * @param d input argument to the log2 function 
60        * @return  base 2 log. 
61        */ 
62       public static int getLogBase2(double d) { 
63           return (int) (Math.log(d) / Math.log(2)); 
64       } 
65    
66       public static final double getGauss( 
67               double x, 
68               double xc, double sigma) { 
69           double oneOnSigmaSquaredOn2 = 1 / (sigma * sigma) / 2; 
70           return 
71                   Math.exp(-((x - xc) * (x - xc)) * 
72                   oneOnSigmaSquaredOn2) / Math.PI * oneOnSigmaSquaredOn2; 
73       } 
74    
75       public static final double[] getGauss(int n) { 
76           double g[] = new double[n]; 
77           for (int x = 0; x < n; x++) 
78               g[x] = getGauss(x, n / 2, 2); 
79           return g; 
80       } 
81    
82       public static final void testGauss() { 
83           print(getGauss(10)); 
84       } 
85    
86       public static final void print(double d[]) { 
87           for (int i = 0; i < d.length; i++) 
88               System.out.println(d[i]); 
89       } 
90   } 
91