random


1   package gnu.brl;
2   
3   // read.java -- procedure to read a BRL expression
4   // Copyright (C) 2000  Bruce R. Lewis and Eaton Vance Management
5   // See the file COPYING for license terms.
6   
7   import kawa.lang.*;
8   import gnu.mapping.Procedure1;
9   import gnu.mapping.WrongType;
10  import gnu.mapping.InPort;
11  import gnu.math.*;
12  
13  public class random extends Procedure1 {
14  
15      static java.util.Random   prg = new java.util.Random  ();
16  
17      public final Object   apply1 (Object   arg1)
18      {
19      IntNum retval = new IntNum();
20  
21      // When passed an integer N, return an int M s.t. 0 <= M < N.
22      if (arg1 instanceof IntNum)
23          {
24          IntNum.divide(IntNum.makeU(Math.abs(prg.nextLong()) >> 1),
25                    (IntNum) arg1, null, retval, Numeric.FLOOR);
26          return retval;
27          }
28  
29      // InPort, e.g. /dev/random, for initializing generator
30      if (arg1 instanceof InPort)
31          try
32          {
33              InPort i = (InPort)arg1;
34              prg.setSeed((long)
35                  i.read()
36                  + i.read() << 8
37                  + i.read() << 16
38                  + i.read() << 24);
39              i.close();
40              return retval;
41          }
42          catch (java.io.IOException   e)
43          {
44              throw new GenericError ("I/O exception in brl-random: "
45                          + e.toString ());
46          }
47      throw new WrongType (this, 1, arg1, "real");
48      }
49  }
50
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