# Dimension mismatch
**URL:** https://discourse.julialang.org/t/dimension-mismatch/101997
**Category:** New to Julia
**Tags:** gridap
**Created:** [July 24, 2023, 1:00am UTC](https://discourse.julialang.org/t/dimension-mismatch/101997 "2023-07-24T01:00:00Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@mary](https://discourse.julialang.org/u/mary)
#### Post date: [July 24, 2023, 1:00am UTC](https://discourse.julialang.org/t/dimension-mismatch/101997/1 "2023-07-24T01:00:00Z")
Hi, I have question on [tutorial 18](https://gridap.github.io/Tutorials/dev/pages/t018_TopOptEMFocus/) of gridap. I have run the same code for my problem but it seems that there is some inconsistency with dimensions in my result. and it works when multiplying one input variable by 1e9. I am confused can any one provide me some clarification? I really appreciate, I am really confused.
there should be some points because the same problem is solved in arbitrary unit in t[utorial 12](https://gridap.github.io/Tutorials/dev/pages/t012_emscatter/) while it is exactly mentioned in tutorial 18 that units are in nm
thank you
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### Author:  [@algunion](https://discourse.julialang.org/u/algunion)
#### Post date: [July 24, 2023, 1:16am UTC](https://discourse.julialang.org/t/dimension-mismatch/101997/2 "2023-07-24T01:16:49Z")
It would be much easier to identify the issue and provide advice if you could add to your post the exact code you are running.
Otherwise, we need to go and do some additional work to put together the code from the example and hope to get into the same issue that you did.
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### Author:  [@mary](https://discourse.julialang.org/u/mary)
#### Post date: [July 24, 2023, 1:19am UTC](https://discourse.julialang.org/t/dimension-mismatch/101997/3 "2023-07-24T01:19:29Z")
thank you. i do not really want to exactly some one debug the code which takes time a lot. I just want to know about the points on that tutorials
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### Author:  [@algunion](https://discourse.julialang.org/u/algunion)
#### Post date: [July 24, 2023, 1:34am UTC](https://discourse.julialang.org/t/dimension-mismatch/101997/4 "2023-07-24T01:34:17Z")
OK. If this is not code-related, then let’s hope that someone familiar with tutorials will jump in and help you with the conceptual part.
I am not familiar with the materials and it would take quite a while to go over both 12 and 18.
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### Author:  [@mary](https://discourse.julialang.org/u/mary)
#### Post date: [July 24, 2023, 1:36am UTC](https://discourse.julialang.org/t/dimension-mismatch/101997/5 "2023-07-24T01:36:25Z")
I really appreciate.