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    • EmperoR

      Dear Guests   12/24/2016

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sAnSiBaR

Calculate direction / angle between polar coordinates

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sAnSiBaR    32

Hi folks,

I think there would be a simple geodetic solution for my question, but let's see:

I want to get the direction like on a compass between 0° and 360° between two polar coordinates.
How does this work?

for example:
r_1 = 4.47 theta_1 = 63.4
r_2 = 6.32 theta_2 = 71.6

For the result it does not matter if north or south, nor if it's 90° or 270°, only the absolute value is relevant.
Cartesian coordinates unfortunately dont work in case if points are vertically aligned (infinite slope).

Regards

 

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jorrarro    11

This depends on where do you need to use this calculation. Mostly you can convert them to cartesian and then use application-specific methods to avoid errors.

For example, in Excel you can use IFERROR function to default all divisions by zero (vertically aligned) to 0 or 180 degrees.

In SQL you can use NULLIF on divisors equalling zero and then COALESCE to default value.

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