>         There seems to be two different convention for labeling the angles
> in sperical coordinates. What I have been taught in school, and have seen
> in two different math textbooks is the following: (assuming a right-handed
> coordinate system, with z axis pointing up, and the x axis going out of
> the page, toward the viewer)
> 
>     theta:  angle rotated about the normal, lives in the xy plane,
>     measured
> from the x-axis
>     phi: angle from the normal, measured from the z axis.
> 
Well, in theoretical physics and according to what I have been taught 
at university, it is measured in the following way: 

theta: measured down from the positive z-axis in range 0...Pi 
  (with Pi/2 when it crosses the x-y-plane)
phi: measured (positively/left) around z-axis in the x-y-plane with 
  range 0..2*Pi.
 
x axis: phi=0, theta=Pi/2
y axis: phi=Pi/2, theta=Pi/2
z axis: theta=0, phi=irrelevant

    / sin(theta) * cos(phi) \
r = | sin(theta) * sin(phi) |
    \ cos(theta)            /

The right-handed system: r,theta,phi
(while r,phi,theta is a left-handed system)

[Quoted from memory but pretty sure it is correct.]

HTH,
Wolfgang

Post a reply to this message