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1 package JSci.maths.symbolic;
2
3 import JSci.maths.*;
4 import JSci.maths.fields.*;
5 import JSci.maths.groups.*;
6
7 import java.util.*;
8
9 class Power extends Expression {
10
11 private final Expression base;
12 private final int exponent;
13
14 public Power(Expression b,int e) {
15 base=b;
16 exponent=e;
17 }
18
19 public Expression getBase() {return base;}
20 public int getExponent() {return exponent;}
21
22 public String  toString() {
23 String r = "";
24 int ep;
25 if (base.getPriority()<getPriority()) r+="("+base+")";
26 else r+=""+base;
27 r+="^";
28 if (exponent>=0) ep=20; else ep=0;
29 if (ep<getPriority()) r+="("+exponent+")";
30 else r+=""+exponent;
31 return r;
32 }
33
34 public Expression differentiate(Variable x) {
35 return new Product(new Expression[] {
36 new Constant(new MathDouble(exponent)),
37 new Power(base,exponent-1),
38 base.differentiate(x)
39 });
40 }
41
42 public Expression evaluate() {
43 Expression b = base.evaluate();
44 if (b instanceof Constant) {
45 Field.Member p = (Field.Member)((Ring)((Constant)b).getValue().getSet()).one();
46 if (exponent>=0) {
47 Ring.Member c = (Ring.Member)((Constant)b).getValue();
48 for (int j=0;j<exponent;j++)
49 p=(Field.Member)p.multiply((Field.Member)c);
50 }
51 else {
52 Field.Member c = (Field.Member)((Constant)b).getValue();
53 c=c.inverse();
54 for (int j=0;j<-exponent;j++) p=(Field.Member)p.multiply(c);
55 }
56 return new Constant(p);
57 }
58 if (exponent==0) return new Constant(((Ring)base.getSet()).one());
59 if (exponent==1) return base;
60 return new Power(b,exponent);
61 }
62
63 protected int getPriority() {return 15;}
64
65 public Object getSet() { return base.getSet(); }
66
67 }
68
69
70
71 |
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