Class: Rational

Inherits:

Object

• Object
• Rational

Defined in:

lib/long-decimal.rb

Constant Summary

FLOAT_MAX_I =

Float::MAX.to_i

FLOAT_SIGNIFICANT_I =

2**56

Instance Method Summary

• #eql?(other) ⇒ Boolean

  fix eql? for Ruby 1.8.

• #to_f ⇒ Object

  improved to_f, works better where numerator and denominator are integers beyond the range of float, but their Quotient is still expressable as Float.

• #to_f_orig ⇒ Object

  retain original to_f under different name.

• #to_ld(prec = nil, mode = LongMath.standard_mode) ⇒ Object

  convert self to LongDecimal.

Instance Method Details

#eql?(other) ⇒ Boolean

fix eql? for Ruby 1.8

Returns:

• (Boolean)

# File 'lib/long-decimal.rb', line 2972

def eql?(other)
  (other.kind_of? Rational) && self.numerator == other.numerator && self.denominator == other.denominator
end

#to_f ⇒ Object

improved to_f, works better where numerator and denominator are integers beyond the range of float, but their Quotient is still expressable as Float

# File 'lib/long-decimal.rb', line 2977

def to_f
  num = numerator
  den = denominator
  # puts("num=#{num} den=#{den}")
  sign = num <=> 0
  # puts("num=#{num} den=#{den} sign=#{sign}")
  if (sign.zero?)
    return 0.0
  elsif sign < 0
    num = -num
  end
  num_big = nil
  den_big = nil
  while num >= FLOAT_SIGNIFICANT_I && den >= FLOAT_SIGNIFICANT_I && (num >= FLOAT_MAX_I || den >= FLOAT_MAX_I)
    num += 0x80
    num >>= 8
    den += 0x80
    den >>= 8
  end

  if num >= FLOAT_MAX_I
    num = (num + den/2) / den
    return (sign * num).to_f
  elsif den >= FLOAT_MAX_I
    den = (den + num/2) / num
    if (den >= FLOAT_MAX_I)
      return 0.0
    else
      return sign/den.to_f
    end
  else
    return sign * (num.to_f / den.to_f)
  end
end

#to_f_orig ⇒ Object

retain original to_f under different name

# File 'lib/long-decimal.rb', line 2964

alias :to_f_orig :to_f

#to_ld(prec = nil, mode = LongMath.standard_mode) ⇒ Object

convert self to LongDecimal. Special handling of Rational to avoid loosing information in the first step that would be needed for the second step optional first argument gives the precision for the desired result optional second argument gives the rouding mode

# File 'lib/long-decimal.rb', line 2954

def to_ld(prec = nil, mode = LongMath.standard_mode)
  if (prec.nil?)
    return LongDecimal(self)
  else
    l = LongDecimalQuot(self, prec)
    return l.round_to_scale(prec, mode)
  end
end