Class: Numerals::FloatConversion

Inherits:
ContextConversion show all
Defined in:
lib/numerals/conversions/float.rb

Instance Attribute Summary

Attributes inherited from ContextConversion

#context, #input_rounding, #type

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ FloatConversion

Options:

  • :input_rounding (optional, a non-exact Rounding or rounding mode) which is used when input is approximate as the assumed rounding mode which would be used so that the result numeral rounds back to the input number



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# File 'lib/numerals/conversions/float.rb', line 12

def initialize(options={})
  super Float, options
end

Instance Method Details

#exact?(value, options = {}) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/numerals/conversions/float.rb', line 34

def exact?(value, options={})
  options[:exact]
end

#number_of_digits(value, options = {}) ⇒ Object 



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# File 'lib/numerals/conversions/float.rb', line 25

def number_of_digits(value, options={})
  base = options[:base] || 10
  if base == @context.radix
    @context.precision
  else
    @context.necessary_digits(base)
  end
end

#number_to_numeral(number, mode, rounding) ⇒ Object

mode is either :exact or :approximate



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# File 'lib/numerals/conversions/float.rb', line 39

def number_to_numeral(number, mode, rounding)
  if @context.special?(number)
    special_float_to_numeral(number)
  else
    if mode == :exact
      exact_float_to_numeral number, rounding
    else # mode == :approximate
      approximate_float_to_numeral(number, rounding)
    end
  end
end

#numeral_to_number(numeral, mode) ⇒ Object 



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# File 'lib/numerals/conversions/float.rb', line 51

def numeral_to_number(numeral, mode)
  if numeral.special?
    special_numeral_to_float numeral
  elsif mode == :fixed
    fixed_numeral_to_float numeral
  else # mode == :free
    free_numeral_to_float numeral
  end
end

#order_of_magnitude(value, options = {}) ⇒ Object 



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# File 'lib/numerals/conversions/float.rb', line 16

def order_of_magnitude(value, options={})
  base = options[:base] || 10 # @contex.radix
  if base == 10
    Math.log10(value.abs).floor + 1
  else
    (Math.log(value.abs)/Math.log(base)).floor + 1
  end
end

#read(numeral, exact_input, approximate_simplified) ⇒ Object 



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# File 'lib/numerals/conversions/float.rb', line 93

def read(numeral, exact_input, approximate_simplified)
  if numeral.special?
    special_numeral_to_float numeral
  # elsif numeral.approximate? && !exact_input
  #   if approximate_simplified
  #     # akin to @context.Num(numeral_text, :short)
  #     short_numeral_to_float numeral
  #   else
  #     # akin to @context.Num(numeral_text, :free)
  #     free_numeral_to_float numeral
  #   end
  else
    # akin to @context.Num(numeral_text, :fixed)
    fixed_numeral_to_float numeral
  end
end

#write(number, exact_input, output_rounding) ⇒ Object 



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# File 'lib/numerals/conversions/float.rb', line 61

def write(number, exact_input, output_rounding)
  output_base = output_rounding.base
  input_base = @context.radix

  if @context.special?(number)
    special_float_to_numeral number
  elsif exact_input
    if output_base == input_base && output_rounding.free?
      # akin to number.format(base: output_base, simplified: true)
      general_float_to_numeral number, output_rounding, false
    else
      # akin to number.format(base: output_base, exact: true)
      exact_float_to_numeral number, output_rounding
    end
  else
    if output_base == input_base && output_rounding.preserving?
      # akin to number.format(base: output_base)
      sign, coefficient, exp = @context.split(number)
      Numerals::Numeral.from_coefficient_scale(
        sign*coefficient, exp,
        approximate: true, base: output_base
      )
    elsif output_rounding.simplifying?
      # akin to number.forma(base: output_base, simplify: true)
      general_float_to_numeral number, output_rounding, false
    else
      # akin to number.forma(base: output_base, all_digits: true)
      general_float_to_numeral number, output_rounding, true
    end
  end
end