Problem in coordinate conversion

I am trying to convert coordinate from cartesian to polar and polar to cartesian.

Results are fine in case of polar to cartesian ( using [x, y, z] = pol2cart(th, rho, z) ). But when i tried to convert cartesian to polar (using [th, rho, z] = cart2pol(x, y, z) ), it doest not give desired results. As the angle is decreasing after 180.

Data Used:

x y z

-14.878048 1.563746 -327.42304

-14.903073 1.30385 -329.891304

-14.923558 1.043557 -331.798206

-14.939498 0.782946 -333.19258

-14.950887 0.522096 -334.124542

-14.957722 0.261088 -334.64534

-14.96 0 -334.807194

-14.957722 -0.261088 -334.663137

-14.950887 -0.522096 -334.266858

-14.939498 -0.782946 -333.672529

-14.923558 -1.043557 -332.934651

Wrong Results:

th rh z

174 14.9600004626611 -327.423040000000

175 14.9600003230558 -329.891304000000

176 14.9599998192384 -331.798206000000

177 14.9600001648035 -333.192580000000

178 14.9600002112294 -334.124542000000

179 14.9600004803819 -334.645340000000

180 14.9600000000000 -334.807194000000

-179 14.9600004803819 -334.663137000000

-178 14.9600002112294 -334.266858000000

-177 14.9600001648035 -333.672529000000

-176 14.9599998192384 -332.934651000000

Desired Results:

th rh z

174 14.96 -327.42304

175 14.96 -329.891304

176 14.96 -331.798206

177 14.96 -333.19258

178 14.96 -334.124542

179 14.96 -334.64534

180 14.96 -334.807194

181 14.96 -334.663137

182 14.96 -334.266858

183 14.96 -333.672529

184 14.96 -332.934651

[Joel Handy]

Those angles appear to match up. Sounds like you want your ansers to be in the range 0 to 360 (0 to 2PI) while the cart2pol function outputs in the range of -180 to 180 [-pi to pi].

You'll have to do a little converserion for yourself to get values in the range you want them in. Something like ...

th(th<0) = 360 + th(th<0);

[Rajbir Singh]

Thank you Joel, it works.

[Rik]

@Joel please put your answer in the answer section. Then Rajbir can accept whichever answer works best for them.

Answer 1

[Rik]

This behavior is as documented. The result is in the [-pi pi] radians range. If you want to have your angles in the range [0 360] degrees, you can use the mod function:

mod(-179,360)
%returns 181