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Code - Class EDU.oswego.cs.dl.util.concurrent.misc.Fraction
1 /*
2 File: Fraction.java
3
4 Originally written by Doug Lea and released into the public domain.
5 This may be used for any purposes whatsoever without acknowledgment.
6 Thanks for the assistance and support of Sun Microsystems Labs,
7 and everyone contributing, testing, and using this code.
8
9 History:
10 Date Who What
11 7Jul1998 dl Create public version
12 11Oct1999 dl add hashCode
13 */
14
15 package EDU.oswego.cs.dl.util.concurrent.misc;
16
17
18 /**
19 * An immutable class representing fractions as pairs of longs.
20 * Fractions are always maintained in reduced form.
21 **/
22 public class Fraction implements Cloneable, Comparable, java.io.Serializable {
23 protected final long numerator_;
24 protected final long denominator_;
25
26 /** Return the numerator **/
27 public final long numerator() { return numerator_; }
28
29 /** Return the denominator **/
30 public final long denominator() { return denominator_; }
31
32 /** Create a Fraction equal in value to num / den **/
33 public Fraction(long num, long den) {
34 // normalize while constructing
35 boolean numNonnegative = (num >= 0);
36 boolean denNonnegative = (den >= 0);
37 long a = numNonnegative? num : -num;
38 long b = denNonnegative? den : -den;
39 long g = gcd(a, b);
40 numerator_ = (numNonnegative == denNonnegative)? (a / g) : (-a / g);
41 denominator_ = b / g;
42 }
43
44 /** Create a fraction with the same value as Fraction f **/
45 public Fraction(Fraction f) {
46 numerator_ = f.numerator();
47 denominator_ = f.denominator();
48 }
49
50 public String toString() {
51 if (denominator() == 1)
52 return "" + numerator();
53 else
54 return numerator() + "/" + denominator();
55 }
56
57 public Object clone() { return new Fraction(this); }
58
59 /** Return the value of the Fraction as a double **/
60 public double asDouble() {
61 return ((double)(numerator())) / ((double)(denominator()));
62 }
63
64 /**
65 * Compute the nonnegative greatest common divisor of a and b.
66 * (This is needed for normalizing Fractions, but can be
67 * useful on its own.)
68 **/
69 public static long gcd(long a, long b) {
70 long x;
71 long y;
72
73 if (a < 0) a = -a;
74 if (b < 0) b = -b;
75
76 if (a >= b) { x = a; y = b; }
77 else { x = b; y = a; }
78
79 while (y != 0) {
80 long t = x % y;
81 x = y;
82 y = t;
83 }
84 return x;
85 }
86
87 /** return a Fraction representing the negated value of this Fraction **/
88 public Fraction negative() {
89 long an = numerator();
90 long ad = denominator();
91 return new Fraction(-an, ad);
92 }
93
94 /** return a Fraction representing 1 / this Fraction **/
95 public Fraction inverse() {
96 long an = numerator();
97 long ad = denominator();
98 return new Fraction(ad, an);
99 }
100
101
102 /** return a Fraction representing this Fraction plus b **/
103 public Fraction plus(Fraction b) {
104 long an = numerator();
105 long ad = denominator();
106 long bn = b.numerator();
107 long bd = b.denominator();
108 return new Fraction(an*bd+bn*ad, ad*bd);
109 }
110
111 /** return a Fraction representing this Fraction plus n **/
112 public Fraction plus(long n) {
113 long an = numerator();
114 long ad = denominator();
115 long bn = n;
116 long bd = 1;
117 return new Fraction(an*bd+bn*ad, ad*bd);
118 }
119
120 /** return a Fraction representing this Fraction minus b **/
121 public Fraction minus(Fraction b) {
122 long an = numerator();
123 long ad = denominator();
124 long bn = b.numerator();
125 long bd = b.denominator();
126 return new Fraction(an*bd-bn*ad, ad*bd);
127 }
128
129 /** return a Fraction representing this Fraction minus n **/
130 public Fraction minus(long n) {
131 long an = numerator();
132 long ad = denominator();
133 long bn = n;
134 long bd = 1;
135 return new Fraction(an*bd-bn*ad, ad*bd);
136 }
137
138
139 /** return a Fraction representing this Fraction times b **/
140 public Fraction times(Fraction b) {
141 long an = numerator();
142 long ad = denominator();
143 long bn = b.numerator();
144 long bd = b.denominator();
145 return new Fraction(an*bn, ad*bd);
146 }
147
148 /** return a Fraction representing this Fraction times n **/
149 public Fraction times(long n) {
150 long an = numerator();
151 long ad = denominator();
152 long bn = n;
153 long bd = 1;
154 return new Fraction(an*bn, ad*bd);
155 }
156
157 /** return a Fraction representing this Fraction divided by b **/
158 public Fraction dividedBy(Fraction b) {
159 long an = numerator();
160 long ad = denominator();
161 long bn = b.numerator();
162 long bd = b.denominator();
163 return new Fraction(an*bd, ad*bn);
164 }
165
166 /** return a Fraction representing this Fraction divided by n **/
167 public Fraction dividedBy(long n) {
168 long an = numerator();
169 long ad = denominator();
170 long bn = n;
171 long bd = 1;
172 return new Fraction(an*bd, ad*bn);
173 }
174
175 /** return a number less, equal, or greater than zero
176 * reflecting whether this Fraction is less, equal or greater than
177 * the value of Fraction other.
178 **/
179 public int compareTo(Object other) {
180 Fraction b = (Fraction)(other);
181 long an = numerator();
182 long ad = denominator();
183 long bn = b.numerator();
184 long bd = b.denominator();
185 long l = an*bd;
186 long r = bn*ad;
187 return (l < r)? -1 : ((l == r)? 0: 1);
188 }
189
190 /** return a number less, equal, or greater than zero
191 * reflecting whether this Fraction is less, equal or greater than n.
192 **/
193
194 public int compareTo(long n) {
195 long an = numerator();
196 long ad = denominator();
197 long bn = n;
198 long bd = 1;
199 long l = an*bd;
200 long r = bn*ad;
201 return (l < r)? -1 : ((l == r)? 0: 1);
202 }
203
204 public boolean equals(Object other) {
205 return compareTo((Fraction)other) == 0;
206 }
207
208 public boolean equals(long n) {
209 return compareTo(n) == 0;
210 }
211
212 public int hashCode() {
213 return (int) (numerator_ ^ denominator_);
214 }
215
216 }
217
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