def __init__(self,n,m,A,B):
self.n=n
self.m=m
self.A=A
self.B=B
self.Bz=SphereHarmonic(n,m,A,B,mode="COS_SIN",harmtype='_{n,m}')
fact=-(1+delta(m,0))/(2.0*(n+m+1))
self.Bxa=SphereHarmonic(n,m+1,A*fact,B*fact,mode="COS_SIN",harmtype='_{n,m}')
self.Bya=SphereHarmonic(n,m+1,-B*fact,A*fact,mode="COS_SIN",harmtype='_{n,m}')
fact=((1-delta(m,0))*(n+m)*(n+m+1))
if fact != 0.0:
fact=fact/(2.0*(n+m+1))
self.Bxb=SphereHarmonic(n,m-1,fact*A,fact*B,mode="COS_SIN",harmtype='_{n,m}')
self.Byb=SphereHarmonic(n,m-1,fact*B,-fact*A,mode="COS_SIN",harmtype='_{n,m}')
class FieldHarmonic:
"""
A Field harmonic described according to Bz=A T_{n,m}+B T_{n,m}^{\prime}
"""
def __init__(self,n,m,A,B):
self.n=n
self.m=m
self.A=A
self.B=B
self.Bz=SphereHarmonic(n,m,A,B,mode="COS_SIN",harmtype='_{n,m}')
fact=-(1+delta(m,0))/(2.0*(n+m+1))
self.Bxa=SphereHarmonic(n,m+1,A*fact,B*fact,mode="COS_SIN",harmtype='_{n,m}')
self.Bya=SphereHarmonic(n,m+1,-B*fact,A*fact,mode="COS_SIN",harmtype='_{n,m}')
fact=((1-delta(m,0))*(n+m)*(n+m+1))
if fact != 0.0:
fact=fact/(2.0*(n+m+1))
self.Bxb=SphereHarmonic(n,m-1,fact*A,fact*B,mode="COS_SIN",harmtype='_{n,m}')
self.Byb=SphereHarmonic(n,m-1,fact*B,-fact*A,mode="COS_SIN",harmtype='_{n,m}')
def A_val_point(self,point):
# The vector potential at the point
pass
def S_val_point(self,point):
# The scalar potential at the point
pass
def B_val_point(self,point):
Bx=self.Bxa.val_point(point)+self.Bxb.val_point(point)
By=self.Bya.val_point(point)+self.Byb.val_point(point)
Bz=self.Bz.val_point(point)
result=Vector((Bx,By,Bz))
return result
