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source: branches/crossvalidation-2434/HeuristicLab.ExtLibs/HeuristicLab.AutoDiff/1.0/AutoDiff-1.0/Term.cs @ 15509

Last change on this file since 15509 was 8703, checked in by gkronber, 12 years ago

#1960 added HL wrapper plugin for AutoDiff

File size: 4.4 KB
Line 
1using System;
2using System.Collections.Generic;
3using System.Linq;
4using System.Text;
5using System.Diagnostics.Contracts;
6
7namespace AutoDiff
8{
9    /// <summary>
10    /// Base class for all automatically-differentiable terms.
11    /// </summary>
12    [Serializable]
13    [ContractClass(typeof(TermContacts))]
14    public abstract class Term
15    {
16        /// <summary>
17        /// Accepts a term visitor
18        /// </summary>
19        /// <param name="visitor">The term visitor to accept</param>
20        public abstract void Accept(ITermVisitor visitor);
21
22        /// <summary>
23        /// Accepts a term visitor with a generic result
24        /// </summary>
25        /// <typeparam name="TResult">The type of the result from the visitor's function</typeparam>
26        /// <param name="visitor">The visitor to accept</param>
27        /// <returns>The result from the visitor's visit function.</returns>
28        public abstract TResult Accept<TResult>(ITermVisitor<TResult> visitor);
29
30        /// <summary>
31        /// Converts a floating point constant to a constant term.
32        /// </summary>
33        /// <param name="value">The floating point constnat</param>
34        /// <returns>The resulting term.</returns>
35        public static implicit operator Term(double value)
36        {
37            return TermBuilder.Constant(value);
38        }
39
40        /// <summary>
41        /// Constructs a sum of the two given terms.
42        /// </summary>
43        /// <param name="left">First term in the sum</param>
44        /// <param name="right">Second term in the sum</param>
45        /// <returns>A term representing the sum of <paramref name="left"/> and <paramref name="right"/>.</returns>
46        public static Term operator+(Term left, Term right)
47        {
48            if (left is Zero && right is Zero)
49                return new Zero();
50            else if (left is Zero)
51                return right;
52            else if (right is Zero)
53                return left;
54            else
55                return TermBuilder.Sum(left, right);
56        }
57
58        /// <summary>
59        /// Constructs a product term of the two given terms.
60        /// </summary>
61        /// <param name="left">The first term in the product</param>
62        /// <param name="right">The second term in the product</param>
63        /// <returns>A term representing the product of <paramref name="left"/> and <paramref name="right"/>.</returns>
64        public static Term operator*(Term left, Term right)
65        {
66            return TermBuilder.Product(left, right);
67        }
68
69        /// <summary>
70        /// Constructs a fraction term of the two given terms.
71        /// </summary>
72        /// <param name="numerator">The numerator of the fraction. That is, the "top" part.</param>
73        /// <param name="denominator">The denominator of the fraction. That is, the "bottom" part.</param>
74        /// <returns>A term representing the fraction <paramref name="numerator"/> over <paramref name="denominator"/>.</returns>
75        public static Term operator/(Term numerator, Term denominator)
76        {
77            return TermBuilder.Product(numerator, TermBuilder.Power(denominator, -1));
78        }
79
80        /// <summary>
81        /// Constructs a difference of the two given terms.
82        /// </summary>
83        /// <param name="left">The first term in the difference</param>
84        /// <param name="right">The second term in the difference.</param>
85        /// <returns>A term representing <paramref name="left"/> - <paramref name="right"/>.</returns>
86        public static Term operator-(Term left, Term right)
87        {
88            return left + (-1) * right;
89        }
90
91        /// <summary>
92        /// Constructs a negated term
93        /// </summary>
94        /// <param name="term">The term to negate</param>
95        /// <returns>A term representing <c>-term</c>.</returns>
96        public static Term operator-(Term term)
97        {
98            return (-1) * term;
99        }
100    }
101
102    [ContractClassFor(typeof(Term))]
103    abstract class TermContacts : Term
104    {
105        public override void Accept(ITermVisitor visitor)
106        {
107            Contract.Requires(visitor != null);
108        }
109
110        public override TResult Accept<TResult>(ITermVisitor<TResult> visitor)
111        {
112            Contract.Requires(visitor != null);
113            return default(TResult);
114        }
115    }
116
117}
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