coil_application.py 文件源码

def base_vectors(self):
        """ Returns 3 orthognal base vectors, the first one colinear to
            the axis of the loop.
        """
        # normalize n
        n = self.direction / (self.direction**2).sum(axis=-1)

        # choose two vectors perpendicular to n 
        # choice is arbitrary since the coil is symetric about n
        if  np.abs(n[0])==1 :
            l = np.r_[n[2], 0, -n[0]]
        else:
            l = np.r_[0, n[2], -n[1]]

        l /= (l**2).sum(axis=-1)
        m = np.cross(n, l)
        return n, l, m