class Point2d

# File lib/point2d.rb, line 4
def initialize(x=0, y=0)
  @x = x
  @y = y
end

# File lib/point2d.rb, line 17
def *(factor)
  Point2d.new(x*factor, y*factor)
end

# File lib/point2d.rb, line 9
def +(other)
  Point2d.new(x+other.x, y+other.y)
end

# File lib/point2d.rb, line 13
def -(other)
  Point2d.new(x-other.x, y-other.y)
end

# File lib/point2d.rb, line 21
def /(factor)
  Point2d.new(x/factor, y/factor)
end

# File lib/point2d.rb, line 25
def cross(other)
  x*other.y - y*other.x
end

# File lib/point2d.rb, line 30
def dot(other)
  x*other.x + y*other.y
end