spherical coordinates

[Peter Maas]

Paul McGuire wrote:
>>Peter Maas <peter.maas at mplusr.de> writes:
>>
>>>r = sqrt(x**2 + y**2)
>>>phi = atan(y/x)
>>
>>Better use phi=atan2(y,x) in case x=0.  Similarly for the other atan
> 
> calls.
> 
> These are formulas for cylindrical coordinates.

r and phi are 2D spherical coordinates. You have to add a 3rd coordinate
(usually called z) to get cylindrical coordinates.

> The OP was asking for
> spherical coordinates rho, theta, and phi, where:

The OP was asking for spherical coordinates without mentioning
variables or dimensions. I posted the raw 2D and 3D formulas without
bothering about error handling or other implementation issues.

Mit freundlichen Gruessen,

Peter Maas

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