def calc_curvature(self, s):
    '\n        calc curvature\n        '
    dx = self.sx.calcd(s)
    ddx = self.sx.calcdd(s)
    dy = self.sy.calcd(s)
    ddy = self.sy.calcdd(s)
    k = (((ddy * dx) - (ddx * dy)) / (((dx ** 2) + (dy ** 2)) ** (3 / 2)))
    return k
calc curvature
def calc_curvature(self, s):
    '\n        \n        '
    dx = self.sx.calcd(s)
    ddx = self.sx.calcdd(s)
    dy = self.sy.calcd(s)
    ddy = self.sy.calcdd(s)
    k = (((ddy * dx) - (ddx * dy)) / (((dx ** 2) + (dy ** 2)) ** (3 / 2)))
    return k