<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def spherical(coordinates):
 """No error is propagated"""

    c = coordinates
    r = N.linalg.norm(c,axis=0)
    theta = N.arccos(c[2]/r)
    phi = N.arctan2(c[1],c[0])
    return N.column_stack((r,theta,phi))