Class: Expressions

Inherits:
Object show all
Defined in:
lib/rulp/expression.rb

Overview

An LP Expression. A mathematical expression. Can be a constraint or can be the objective function of a LP or MIP problem.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(expressions) ⇒ Expressions

Returns a new instance of Expressions.



7
8
9
 
# File 'lib/rulp/expression.rb', line 7

def initialize(expressions)
  @expressions = expressions
end

Instance Attribute Details

#expressions ⇒ Object

Returns the value of attribute expressions.



6
7
8
 
# File 'lib/rulp/expression.rb', line 6

def expressions
  @expressions
end

Class Method Details

.[](value) ⇒ Object 



45
46
47
48
49
 
# File 'lib/rulp/expression.rb', line 45

def self.[](value)
  return Expressions.new([Fragment.new(value, 1)]) if value.kind_of?(LV)
  return Expressions.new([value]) if value.kind_of?(Fragment)
  return value if value.kind_of?(Expressions)
end

Instance Method Details

#+(other) ⇒ Object 



11
12
13
 
# File 'lib/rulp/expression.rb', line 11

def +(other)
  return Expressions.new(@expressions + [other])
end

#-(other) ⇒ Object 



36
37
38
39
 
# File 'lib/rulp/expression.rb', line 36

def -(other)
  other = -other
  self + other
end

#-@ ⇒ Object 



31
32
33
34
 
# File 'lib/rulp/expression.rb', line 31

def -@
  -self.expressions[0]
  self
end

#evaluate ⇒ Object 



51
52
53
 
# File 'lib/rulp/expression.rb', line 51

def evaluate
  self.expressions.map(&:evaluate).inject(:+)
end

#to_s ⇒ Object 



15
16
17
18
19
 
# File 'lib/rulp/expression.rb', line 15

def to_s
  @expressions.map{|expression|
    [expression.operand < 0 ? " " : " + ", expression.to_s]
  }.flatten[1..-1].join("")
end

#variables ⇒ Object 



21
22
23
 
# File 'lib/rulp/expression.rb', line 21

def variables
  @expressions.map(&:variable)
end