E

# File ext/bigdecimal/lib/bigdecimal/math.rb, line 258
  def E(prec)
    raise ArgumentError, "Zero or negative precision for E" if prec <= 0
    n    = prec + BigDecimal.double_fig
    one  = BigDecimal("1")
    y  = one
    d  = y
    z  = one
    i  = 0
    while d.nonzero? && ((m = n - (y.exponent - d.exponent).abs) > 0)
      m = BigDecimal.double_fig if m < BigDecimal.double_fig
      i += 1
      z *= i
      d  = one.div(z,m)
      y += d
    end
    y
  end