Aren't -180° and 180° the same for a 3D parametric surface graph?

[User_1979]

Hi everyone,

I need to plot some results using the 3D parametric surface graph and these 3 matrix :

• First matrix “theta” : Each column ranges from -180° to 179°    (180x360)

• Second matrix “phi” : Each line ranges from 0° to 89.5° (increasing by 0.5°)   (180x360)

• Third matrix “z” : 180x 360 matrix initialised to 7

First and second matrixes are converted to a polar representation.

My problem is that I reach my goal, a full red circle, only if my matrixes range from -180° to 180° and not when they range from -180° to 179°. Aren’t -180° and 180° the same for this graph? I must be doing something wrong...

Any help would be great,

Thanks.

Regards,

User

[LV_Pro]

I'm not sure I completely understand your question, but I think what you are seeing is that the last degree from 179 to 180 (or -180) isn't being completed.

[User_1979]

Yes that is my problem. I don't understand why I have to send a -180° information to the graph since I have already send a 180°...

[Yamaeda · Accepted solution]

"First matrix “theta” : Each column ranges from -180° to 179° "

I take it this means the 179 to 180 plot is empty. You'll either have to manually connect the last plot (some fix to connect) or simply write the 179 to 180 also.

/Y

[altenbach]

Seems obvious that you need to have the first and last point the same in order to close the curve.

A simpler, but equivalent example is a circle on an xy graph, Unless the first and last point coincide, you won't close the loop. 😉

[User_1979]

Hi Yamaeda,

Thanks for your answer.Since for me in the test -180° and 180 is the same, I had already done that : copy results of line -180° to line 180°. It's true that I forgot that it is a surface representation and not a XY graph.

Regards,

User