Module: Differentiation

Defined in:
lib/differentiation/dual_number.rb,
lib/differentiation.rb,
lib/differentiation/version.rb

Overview

fronzen_string_literal: true

Defined Under Namespace

Classes: DualNumber

Constant Summary collapse

VERSION = 
"0.2.2"

Class Method Summary collapse

Class Method Details

.convert_to_dual_number(o, key: nil, named_variables: {}) ⇒ Object 



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# File 'lib/differentiation.rb', line 11

def self.convert_to_dual_number(o, key: nil, named_variables: {})
  if o.is_a?(DualNumber)
    if key and o.named_variables.empty?
      DualNumber.new(o.n, o.diff, key: key)
    else
      o
    end
  elsif differentiable?(o)
    if defined?(Matrix) and o.is_a?(Matrix)
      if key
        vars = Matrix.build(o.row_size, o.column_size){ nil }
        named_variables = { key => vars }
      end
      Matrix.build(o.row_size, o.column_size) do |i, j|
        v = self.convert_to_dual_number(o[i, j], named_variables: named_variables)
        if key
          vars.__send__(:[]=, i, j, v)
        end
        v
      end
    else
      DualNumber.new(o, key: key, named_variables: named_variables)
    end
  else
    o
  end
end

.differentiable?(o) ⇒ Boolean

Returns:

  • (Boolean) 


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

def self.differentiable?(o)
  o.is_a?(Numeric) or (defined?(Matrix) and o.is_a?(Matrix))
end

.differential(f) ⇒ Object 



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# File 'lib/differentiation.rb', line 39

def self.differential(f)
  unless f.is_a?(Proc) or f.is_a?(Method) or f.is_a?(UnboundMethod)
    raise TypeError, "Only Proc or Method can be differentiable"
  end

  # [[:req, :x], [:req, :y], [:opt, :c], [:rest, :rest], [:keyreq, :k2], [:key, :k1], [:keyrest, :kw]]
  parameters = f.parameters
  positional = []
  parameters.each do |tuple|
    if [:req, :opt].include?(tuple[0])
      positional << tuple[1]
    elsif [:key, :keyreq, :kwrest].include?(tuple[0])
    else
      # TODO: support rest arguments
      raise "rest arguments are currently not supported"
    end
  end
  f_prime = lambda {|*args, **kwargs|
    if f.is_a?(UnboundMethod)
      f = f.bind(self)
    end
    args.map!.with_index do |a, i|
      Differentiation.convert_to_dual_number(a, key: positional[i])
    end
    kwargs = Hash[kwargs.map{|k,v| [k, Differentiation.convert_to_dual_number(v, key: k)] }]
    if kwargs.empty?
      Differentiation.convert_to_dual_number(f.call(*args))
    else
      Differentiation.convert_to_dual_number(f.call(*args, **kwargs))
    end
  }
end