Error in DIVIDEobj in P3

[eemeleems]

Hi Richard,

I've come across an error in P3 that I can't seem to get past.

I've tried a number of ways to fix this in my code - also tried to run the _key file, to check if it was just human error on my part, but this also failed. It seems that cellsize in the Y direction needs to be negative for DIVIDEobj to run? Tried to use flipud to fix it, but this gave an error ('Expected CellExtentInWorldY to be positive').

I understand the 2-day course is now several years old, but I was wondering if you could provide some guidance. It could be due to my laptop or MATLAB version (R2025b), or just my own misunderstanding. All other things up to this point have been successful!

Emily

[Richard-Ott]

Hi Emily, Thanks for letting me know. Indeed the course hasn't been updated in a while and not TopoToolbox 3 head been released, the way of calculating the Divideobj has changed and of course Matlab itself. I'll check and get back to you. Which version of TT are you running? I recommend using the newest and also use ttupdate() to always have the latest version. I'll get back to you in a week or so. Richard Dr. Richard Ott Assistant Professor Ecosystem and Landscape Dynamics University of Amsterdam Emily Adams ***@***.***> schrieb am Mi., 14. Jan. 2026, 18:02:

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*eemeleems* created an issue (Richard-Ott/TT_2day_course#2) <#2> Hi Richard, I've come across an error in P3 that I can't seem to get past. Screenshot.2026-01-14.165005.png (view on web) <https://github.com/user-attachments/assets/cdb236a9-252c-4b62-bc10-99b5a288091a> I've tried a number of ways to fix this in my code - also tried to run the _key file, to check if it was just human error on my part, but this also failed. It seems that cellsize in the Y direction needs to be negative for DIVIDEobj to run? Tried to use flipud to fix it, but this gave an error ('Expected CellExtentInWorldY to be positive'). I understand the 2-day course is now several years old, but I was wondering if you could provide some guidance. It could be due to my laptop or MATLAB version (R2025b), or just my own misunderstanding. All other things up to this point have been successful! Emily — Reply to this email directly, view it on GitHub <#2>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AODIJXRMH3OYDPNJE3P4PID4GZZCNAVCNFSM6AAAAACRWGVSYOVHI2DSMVQWIX3LMV43ASLTON2WKOZTHAYTIMBVGM3TSNY> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[eemeleems]

Hi Richard,

Thanks for your response, it's much appreciated. I'm running TT3, I'm not sure exactly which release, but I installed it on 9th October 2025. Thank you for the tip about ttupdate(), I will use this in future.

Emily

[eemeleems]

Hi Richard,

Just wanted to update, as I've now gone onto the most recent release. There is still an error, but different, and the DIVIDEobj function seems to work better. The divorder function isn't working for me, but I can get past that by removing that line, and a plot is produced.

Emily