Class: Symbolic::Summand

Inherits:
Object
  • Object
show all
Includes:
Symbolic
Defined in:
lib/symbolic/summand.rb

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Symbolic

#*, #**, #+, #+@, #-, #-@, #/, #coerce, #operations, #undefined_variables

Constructor Details

#initialize(summands) ⇒ Summand

Returns a new instance of Summand.



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# File 'lib/symbolic/summand.rb', line 48

def initialize(summands)
  @summands = summands
end

Class Method Details

.add(var1, var2) ⇒ Object 



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# File 'lib/symbolic/summand.rb', line 5

def add(var1, var2)
  simplify_coefficients! summands = unite(summands(var1), summands(var2))
  simplify(*summands) || new(summands)
end

.reverse(var) ⇒ Object 



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# File 'lib/symbolic/summand.rb', line 15

def reverse(var)
  summands(var).tap do |it|
    it[0] = -it[0]
    it[1] = Hash[*it[1].map {|b,e| [b,-e] }.flatten]
  end
end

.simplify(numeric, symbolic) ⇒ Object 



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# File 'lib/symbolic/summand.rb', line 39

def simplify(numeric, symbolic)
  if symbolic.empty?
    numeric
  elsif numeric == 0 && symbolic.size == 1
    symbolic.values.first * symbolic.keys.first
  end
end

.simplify_coefficients!(summands) ⇒ Object 



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# File 'lib/symbolic/summand.rb', line 35

def simplify_coefficients!(summands)
  summands[1].delete_if {|base, coef| coef == 0 }
end

.subtract(var1, var2) ⇒ Object 



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# File 'lib/symbolic/summand.rb', line 10

def subtract(var1, var2)
  simplify_coefficients! summands = unite(summands(var1), reverse(var2))
  simplify(*summands) || new(summands)
end

.summands(var) ⇒ Object 



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# File 'lib/symbolic/summand.rb', line 22

def summands(var)
  var.is_a?(Symbolic) ? var.send(:summands) : [var, {}]
end

.unite(summands1, summands2) ⇒ Object 



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# File 'lib/symbolic/summand.rb', line 26

def unite(summands1, summands2)
  numeric1, symbolic1 = summands1
  numeric2, symbolic2 = summands2

  numeric = numeric1 + numeric2
  symbolic = symbolic1.merge(symbolic2) {|base, coef1, coef2| coef1 + coef2 }
  return numeric, symbolic
end

Instance Method Details

#==(object) ⇒ Object 



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# File 'lib/symbolic/summand.rb', line 60

def ==(object)
  object.send(:summands) == @summands rescue false
end

#to_s ⇒ Object 



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# File 'lib/symbolic/summand.rb', line 64

def to_s
  output = @summands[1].map {|base, coef| coef_to_string(coef) + base.to_s }
  output << remainder_to_string(@summands[0]) if @summands[0] != 0
  output[0] = output.first[1..-1]
  output.join
end

#value ⇒ Object 



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# File 'lib/symbolic/summand.rb', line 52

def value
  @summands[1].inject(@summands[0]) {|value, (base, coef)| value + base.value * coef.value }
end

#variables ⇒ Object 



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# File 'lib/symbolic/summand.rb', line 56

def variables
  @summands[1].map {|k,v| [variables_of(k), variables_of(v)] }.flatten.uniq
end