Finding the sign of $\phi$ in spherical coordinates

1.5k Views Asked by At

I know its a little silly, but I got the wrong sign several times. Just to be clear, $z=r\cos(\phi), -\frac{\pi}{2}\leq\phi\leq\frac{\pi}{2}$ when converting from cartesian to spherical. So, how do I determine the sign? Thanks!

1

There are 1 best solutions below

0
On

The spherical coordinate system I learned has $z=r \cos \theta$ with $0 \le \theta \le \pi$. For that range of $\phi$ you need to use $z=r \sin(\phi)$, in which case you can get the sign. I have seen geographers use this, though they usually use $\lambda$ for latitude