'**SUMMARY**
This helper method normalizes the vector give an input magnitude.
This is helpful for keeping the flow vector inside the sample window.'

def normalizeTo(self, max_mag):

    if (max_mag == 0):
        self.norm_dx = 0
        self.norm_dy = 0
        return None
    mag = self.magnitude()
    new_mag = (mag / max_mag)
    unit = self.unitVector()
    self.norm_dx = (unit[0] * new_mag)
    self.norm_dy = (unit[1] * new_mag)
