Quantity


1   // Copyright (c) 1997  Per M.A. Bothner.
2   // This is free software;  for terms and warranty disclaimer see ./COPYING.
3   
4   package gnu.math;
5   
6   /** A quantity with a unit.
7    * This generalizes the DSSSL quantity type (to more than lengths).
8    * @author  Per Bothner
9    */
10  
11  public abstract class Quantity extends Numeric
12  {
13    public Unit unit() { return Unit.Empty; }
14    public Dimensions dimensions() { return unit().dimensions(); }
15  
16    public abstract Complex number ();
17  
18    /** The value of the real component, as a RealNum.
19     * The unit() is not factored in, so you actually need to multiply
20     * by unit() to get the true real component.
21     */
22    public RealNum re () { return number().re(); }
23  
24    /** The value of the imaginary component, as a RealNum.
25     * The unit() is not factored in, so you actually need to multiply
26     * by unit() to get the true imaginary component.
27     */
28    public RealNum im () { return number().im(); }
29  
30    /** The value of the real component, as a double.
31     * This is relative to the unit().dims - i.e. unit().doubleValue()
32     * is factored in.
33     * A final alias for the virtual doubleValue. */
34    public final double reValue() { return doubleValue(); }
35  
36    /** The value of the imaginary component, as a double.
37     * This is relative to the unit().dims - i.e. unit().doubleValue()
38     * is factored in.
39     * A final alias for the virtual doubleImagValue. */
40    public final double imValue() { return doubleImagValue(); }
41  
42    /** The value of the real component, as a double.
43     * This is relative to the unit().dims - i.e. unit()/doubleValue()
44     * is factored in. */
45    public double doubleValue ()
46    { return unit().doubleValue() * re().doubleValue (); }
47  
48    /** The value of the imaginary component, as a double.
49     * This is relative to the unit().dims - i.e. unit()/doubleValue()
50     * is factored in. */
51    public double doubleImagValue() {return unit().doubleValue() * im().doubleValue ();}
52  
53    public static Quantity make (Complex x, Unit u)
54    {
55      if (u == Unit.Empty)
56        return x;
57      if (x instanceof DFloNum)
58        return new DQuantity (x.doubleValue(), u);
59      return new CQuantity (x, u);
60    }
61  
62    public static Quantity make (RealNum re, RealNum im, Unit unit)
63    {
64      if (unit == Unit.Empty)
65        return Complex.make (re, im);
66      if (im.isZero () && (!re.isExact() || !im.isExact()))
67        return new DQuantity(re.doubleValue(), unit);
68      return new CQuantity (re, im, unit);
69    }
70  
71    public static Quantity make (double re, double im, Unit unit)
72    {
73      if (unit == Unit.Empty)
74        return Complex.make (re, im);
75      if (im == 0.0)
76        return new DQuantity(re, unit);
77      return new CQuantity (new DFloNum(re), new DFloNum(im), unit);
78    }
79  
80    /*
81    public static Quantity make (Quantity x, Quantity y)
82    {
83      double x_factor = x.unit().doubleValue();
84      if (x.unit() != y.unit())
85        {
86      if (x.dimensions() != y.dimensions())
87        throw new ArithmeticException ("units mis-match");
88      double re = x.doubleValue() / x_factor;
89      double im = y.doubleValue() / x_factor;
90      return Complex.make (re, im, x.unit());
91        }
92      if (! x.isExact() || ! y.isExact())
93        {
94      return Complex.make (x.doubleValue () / x_factor,
95                   y.doubleValue () / x_factor, x.unit());
96        }
97      return Complex.make (x.re(), y.re(), x.unit());
98    }
99    */
100 
101   public Numeric neg () { return make ((Complex) number().neg(), unit()); }
102   public Numeric abs () { return make ((Complex) number().abs(), unit()); }
103 
104   public static int compare (Quantity x, Quantity y)
105   {
106     if (x.unit() == y.unit())
107       return Complex.compare(x.number(), y.number());
108     if (x.dimensions() != y.dimensions() || x.imValue() != y.imValue())
109       return -3;
110     return DFloNum.compare(x.reValue(), y.reValue());
111   }
112 
113   public int compare (Object   obj)
114   {
115     if (! (obj instanceof Quantity))
116       return ((Numeric) obj).compareReversed(this);
117     return compare(this, (Quantity) obj);
118   }
119 
120   public int compareReversed (Numeric x)
121   {
122     if (x instanceof Quantity)
123       return compare((Quantity)x, this);
124     throw new IllegalArgumentException   ();
125   }
126 
127   public static Quantity add (Quantity x, Quantity y, int k)
128   {
129     if (x.unit() == y.unit())
130       return make (Complex.add (x.number(), y.number(), k), x.unit());
131     else if (x.dimensions() != y.dimensions())
132       throw new ArithmeticException   ("units mis-match");
133     else
134       {
135     double x_factor = x.unit().doubleValue();
136     double re = (x.reValue() + k * y.reValue()) / x_factor;
137     double im = (x.imValue() + k * y.imValue()) / x_factor;
138     return Quantity.make (re, im, x.unit());
139       }
140   }
141 
142   public Numeric add (Object   y, int k)
143   {
144     if (y instanceof Quantity)
145       return add (this, (Quantity) y, k);
146     return ((Numeric)y).addReversed (this, k);
147   }
148 
149   public Numeric addReversed (Numeric x, int k)
150   {
151     if (x instanceof Quantity)
152       return add ((Quantity)x, this, k);
153     throw new IllegalArgumentException   ();
154   }
155 
156   public static Quantity times (Quantity x, Quantity y)
157   {
158     Unit unit = Unit.times(x.unit(), y.unit());
159     // return Quantity.make (Complex.times(x.number(), y.number()), unit);
160     Numeric num = x.number().mul(y.number());
161     return Quantity.make ((Complex) num, unit);
162   }
163 
164   public Numeric mul (Object   y)
165   {
166     if (y instanceof Quantity)
167       return times(this, (Quantity) y);
168     return ((Numeric)y).mulReversed (this);
169   }
170 
171   public Numeric mulReversed (Numeric x)
172   {
173     if (x instanceof Quantity)
174       return times((Quantity) x, this);
175     throw new IllegalArgumentException   ();
176   }
177 
178   public static Quantity divide (Quantity x, Quantity y)
179   {
180     Unit unit = Unit.divide (x.unit(), y.unit());
181     Numeric num = x.number().div(y.number());
182     return Quantity.make ((Complex) num, unit);
183   }
184 
185   public Numeric div (Object   y)
186   {
187     if (y instanceof Quantity)
188       return divide(this, (Quantity) y);
189     return ((Numeric)y).divReversed (this);
190   }
191 
192   public Numeric divReversed (Numeric x)
193   {
194     if (x instanceof Quantity)
195       return divide((Quantity)x, this);
196     throw new IllegalArgumentException   ();
197   }
198 
199   public String   toString (int radix)
200   {
201     String   str = number ().toString (radix);
202     if (unit () == Unit.Empty)
203       return str;
204     return str + unit ().toString ();
205   }
206 }
207
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