# Math will convert unit objects to radians and then attempt to use the value for 
# trigonometric functions.  
require 'mathn'

module Math

  alias :unit_sqrt :sqrt
  def sqrt(n)
    if Unit === n
      (n**(Rational(1,2))).to_unit 
    else
      unit_sqrt(n)
    end
  end
  module_function :unit_sqrt
  module_function :sqrt

  if self.respond_to?(:cbrt)
    alias :unit_cbrt :cbrt
    def cbrt(n)
      if Unit === n
        (n**(Rational(1,3))).to_unit 
      else
        unit_cbrt(n)
      end
    end
    module_function :unit_cbrt
    module_function :cbrt
  end
  
  alias :unit_sin :sin
  def sin(n)
   Unit === n ? unit_sin(n.to('radian').scalar) : unit_sin(n)
  end
  module_function :unit_sin
  module_function :sin

  alias :unit_cos :cos
  def cos(n)
    Unit === n ? unit_cos(n.to('radian').scalar) : unit_cos(n)
  end
  module_function :unit_cos
  module_function :cos
    
  alias :unit_sinh :sinh
  def sinh(n)
    Unit === n ? unit_sinh(n.to('radian').scalar) : unit_sinh(n)
  end
  module_function :unit_sinh
  module_function :sinh

  alias :unit_cosh :cosh
  def cosh(n)
    Unit === n ? unit_cosh(n.to('radian').scalar) : unit_cosh(n)
  end
  module_function :unit_cosh
  module_function :cosh

  alias :unit_tan :tan
  def tan(n)
   Unit === n ? unit_tan(n.to('radian').scalar) : unit_tan(n)
  end
  module_function :tan
  module_function :unit_tan

  alias :unit_tanh :tanh
  def tanh(n)
    Unit === n ? unit_tanh(n.to('radian').scalar) : unit_tanh(n)
  end
  module_function :unit_tanh
  module_function :tanh

  alias :unit_hypot :hypot
  # Convert parameters to consistent units and perform the function
  def hypot(x,y)
    if Unit === x && Unit === y
      (x**2 + y**2)**(1/2)
    else
      unit_hypot(x,y)
    end
  end
  module_function :unit_hypot
  module_function :hypot
  
  alias :unit_atan2 :atan2
  def atan2(x,y)
    case
    when (Unit === x && Unit === y) && (x !~ y)
      raise ArgumentError, "Incompatible Units"
    when (Unit === x && Unit === y) && (x =~ y)
      Math::unit_atan2(x.base_scalar, y.base_scalar)
    when (Unit === x || Unit === y)
      raise ArgumentError, "Incompatible Units"
    else
      Math::unit_atan2(x,y)
    end
  end
  module_function :unit_atan2
  module_function :atan2
   
end