Class: Differentiation::DualNumber

Inherits:
Object
  • Object
show all
Includes:
Comparable
Defined in:
lib/differentiation/dual_number.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(n, diff = lambda{|var| var.equal?(self) ? 1.0 : 0.0 }, named_variables: {}, key: nil) ⇒ DualNumber

Returns a new instance of DualNumber.



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# File 'lib/differentiation/dual_number.rb', line 7

def initialize(n, diff=lambda{|var| var.equal?(self) ? 1.0 : 0.0 }, named_variables: {}, key: nil)
  @n = n
  @diff = diff
  if key
    @named_variables = { key => self }.freeze
  else
    @named_variables = named_variables.dup.freeze
  end
end

Instance Attribute Details

#diff ⇒ Object (readonly)

Returns the value of attribute diff.



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# File 'lib/differentiation/dual_number.rb', line 17

def diff
  @diff
end

#n ⇒ Object (readonly)

Returns the value of attribute n.



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# File 'lib/differentiation/dual_number.rb', line 17

def n
  @n
end

#named_variables ⇒ Object (readonly)

Returns the value of attribute named_variables.



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# File 'lib/differentiation/dual_number.rb', line 17

def named_variables
  @named_variables
end

Instance Method Details

#*(other) ⇒ Object 



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# File 'lib/differentiation/dual_number.rb', line 129

def *(other)
  if other.is_a?(DualNumber)
    n = @n * other.n
    diff = ->(var) { @n * other.derivative(var) + self.derivative(var) * other.n }
    named_variables = @named_variables.merge(other.named_variables)
  else
    n = @n * other
    diff = ->(var) { self.derivative(var) * other }
    named_variables = @named_variables
  end
  DualNumber.new(n, diff, named_variables: named_variables)
end

#**(other) ⇒ Object 



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# File 'lib/differentiation/dual_number.rb', line 155

def **(other)
  if other.is_a?(DualNumber)
    n = @n ** other.n
    diff = ->(var) { (@n ** other.n) * (other.derivative(var) * Math.log(@n) + (other.n / @n)) }
    named_variables = @named_variables.merge(other.named_variables)
  else
    n = @n ** other
    diff = ->(var) { ((@n ** (other-1)) * other) * self.derivative(var) }
    named_variables = @named_variables
  end
  DualNumber.new(n, diff, named_variables: named_variables)
end

#+(other) ⇒ Object 



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# File 'lib/differentiation/dual_number.rb', line 103

def +(other)
  if other.is_a?(DualNumber)
    n = @n + other.n
    diff = ->(var) { self.derivative(var) + other.derivative(var) }
    named_variables = @named_variables.merge(other.named_variables)
  else
    n = @n + other
    diff = @diff
    named_variables = @named_variables
  end
  DualNumber.new(n, diff, named_variables: named_variables)
end

#+@ ⇒ Object 



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# File 'lib/differentiation/dual_number.rb', line 95

def +@
  self
end

#-(other) ⇒ Object 



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# File 'lib/differentiation/dual_number.rb', line 116

def -(other)
  if other.is_a?(DualNumber)
    n = @n - other.n
    diff = ->(var) { self.derivative(var) - other.derivative(var) }
    named_variables = @named_variables.merge(other.named_variables)
  else
    n = @n - other
    diff = @diff
    named_variables = @named_variables
  end
  DualNumber.new(n, diff, named_variables: named_variables)
end

#-@ ⇒ Object 



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# File 'lib/differentiation/dual_number.rb', line 99

def -@
  self * -1
end

#/(other) ⇒ Object 



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# File 'lib/differentiation/dual_number.rb', line 142

def /(other)
  if other.is_a?(DualNumber)
    n = @n / other.n
    diff = ->(var) { (self.derivative(var) / other.n) - (@n * other.derivative(var)) / (other.n ** 2) }
    named_variables = @named_variables.merge(other.named_variables)
  else
    n = @n / other
    diff = ->(var) { self.derivative(var) / other }
    named_variables = @named_variables
  end
  DualNumber.new(n, diff, named_variables: named_variables)
end

#<=>(other) ⇒ Object 



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# File 'lib/differentiation/dual_number.rb', line 87

def <=>(other)
  if other.is_a?(DualNumber)
    @n <=> other.n
  else
    @n <=> other
  end
end

#coerce(other) ⇒ Object 



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# File 'lib/differentiation/dual_number.rb', line 79

def coerce(other)
  if Differentiation.differentiable?(other)
    [Differentiation.convert_to_dual_number(other), self]
  else
    super
  end
end

#derivative(var) ⇒ Object 



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# File 'lib/differentiation/dual_number.rb', line 19

def derivative(var)
  if var.equal?(self)
    1.0
  else
    @diff.call(var)
  end
end

#gradients(*keys) ⇒ Object 



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# File 'lib/differentiation/dual_number.rb', line 27

def gradients(*keys)
  keys = keys.flatten(1)
  return_hash = false
  if keys.empty?
    return_hash = true
    keys = @named_variables.keys
    vars = @named_variables.values
  else
    vars = keys.map do |k|
      if k.is_a?(DualNumber) or (defined?(::Matrix) and k.is_a?(Matrix))
        k
      else
        @named_variables[k]
      end
    end
  end
  if return_hash
    keys.each_with_object({}) do |k, o|
      v = @named_variables[k]
      if v.nil?
        o[k] = 0.0
      elsif defined?(::Matrix) and v.is_a?(::Matrix)
        o[k] = Matrix.build(v.row_size, v.column_size){|i, j| derivative(v[i, j]) }
      else
        o[k] = derivative(v)
      end
    end
  else
    vars.map do |v|
      if v.nil?
        0.0
      elsif defined?(::Matrix) and v.is_a?(::Matrix)
        Matrix.build(v.row_size, v.column_size){|i, j| derivative(v[i, j]) }
      else
        derivative(v)
      end
    end
  end
end

#inspect ⇒ Object 



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# File 'lib/differentiation/dual_number.rb', line 168

def inspect
  if $DEBUG
    "<DualNumber: #{@n} >"
  else
    @n.inspect
  end
end

#to_f ⇒ Object 



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# File 'lib/differentiation/dual_number.rb', line 75

def to_f
  @n.to_f
end

#to_i ⇒ Object 



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# File 'lib/differentiation/dual_number.rb', line 67

def to_i
  @n.to_i
end

#to_int ⇒ Object 



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# File 'lib/differentiation/dual_number.rb', line 71

def to_int
  @n.to_int
end