class Float

# File lib/gstring.rb, line 1792
def to_eng(pa=6, unit=nil)
  pa = pa.to_i
  pa = (pa<1) ? 1 : (pa>15) ? 15 : pa
  if self < 0.0
    num = -self
    sgn = "-"
  else
    num = self
    sgn = ""  
  end
  str = "%.16e" % num
  str.extract!(1..1)    # remove decimal point
  num = str.parse('e')
  exp = str.to_i
  pos = (exp%3)+1
  if (exp < 0)
    esgn = "-"
    ee  = -(exp/3)*3
  else
    esgn = ""
    ee = (exp/3)*3
  end
  pd = pos > pa ? pos : pa
  num = (num[0..pa].to_f/10).round.to_s[0..(pa-1)].padto(pd,'0',:right)  # round to target size
  num.insert(pos, '.') unless pos >= (num.length)
  pfx = String::SI_UNIT_PREFIXES["#{esgn}#{ee}".to_i]
  unless unit.nil?
    unless pfx.nil?
      num += pfx
      ee=0 # disable 'e' thing
    end
  end
  unit ||= ""  
  if (ee>0)
    num += "e#{esgn}#{ee}"
  end
  return sgn+num+unit
end

# File lib/gstring.rb, line 1782
def to_num
  self
end

# File lib/gstring.rb, line 1785
def to_scd(dp=2, delim = ',.')
  num = ((10 ** dp) * self).round.to_s
  man = num[0..(-dp-1)]
  man = man.empty? ? '0' : man
  frt = (num[(-dp)..(-1)] || "").padto(dp,'0',:right)
  return man.reverse.scan(/\d{1,3}/).join(delim.first).reverse + delim.last + frt
end