Why do I get this error? If i do it in the command window it seems to be possible

Hi everybody, I have a similar problem and I have absolutely no clue where my mistake is. I get the same error but I don´t see why. I am a beginner at Matlab from germany sitting on my bachelor thesis. WIthin the project my goal is to check whether the point is sitting in a bounding box. Therefor I check the first box, which is described by the 8 Points on the Matrix M, with all the 8 points of my component. I then move on to the next box and so on. However if I go into the second box, I get the following error:

This is my Code or at least the part I think is relevant:

Please help me as I said I´m just getting started, so it´s possible I misunderstood something completely.

Thanks a lot guys,

Johnny

[Geoff Hayes]

Johnny - it's hard to tell from your code screen shot (attaching the m file is easier) but it looks like you have a for loop with

for huellkoper=1:2
    M=M{huellkoper};
    % etc.
end

Do you really mean to set M to some element of M? It could be that the error is firing on the second iteration when M is no longer a cell array... Should the assigned to variable be named something else?

for huellkoper=1:2
    MSubset = M{huellkoper};
    % etc.
end

[Jonathan Babitsch]

Hi Geoff, Thank you a lot for your quick answer, well I guess I misunderstood something here. What I am trying to do is set m to the second matrix shown in line 24, so the first iteration uses the matrix in line 14 as intended is that right? Why isn't it using the second matrix? What I am basically trying is to do is what is in the inner for loop with 4 different bodies, which i intended to describe as M{1}, M{2},M{3},M{4}... And I wanted to import that somehow and then do it in a loop. Is there any possibility or do I have to do it with different variables? I'm looking forward to your response and as I said I'm a beginner, so I'm very thankful for any advice.

Johnny

[Jonathan Babitsch]

If it helps I can upload the file and give a detailed description of what I am trying to do... As I said, big thank you this far

[Walter Roberson]

If we had your actual code instead of a picture of part of the code, we could more easily advise you. The part of the code you show does not use M after the M=M{huellkoerper} line.

[Jonathan Babitsch]

Thanks a lot for your response here Walter and the response you gave under the other article where I asked this too. I have now attached the code of my problem and I am goint to explain what my idea is. So I am having for bounding boxes which are cuboids. So they have 8 vertices. These vertices are written in the matrix M, so i was trying to have 4 different Matrixes M. My idea was to write them into cell arrays. In the for loop I wanted to count them up. So first iteration with my first bounding box, which I wanted to call M{1} and then count up whats inside the bracket to {huellkoerper} (german for bounding box), so make Huellkoerper=2 and get the second Matrix M{2}. Inside the for loop, I want to look whether the Vertices of my Component K are inside the Bounding Box. Therefor I am putting lines through the vertices of my component to intersect with the plane of my bounding box, described as the Matrix M. I will get 6 intersections per point K with the body of my bounding box, so one in each plane. This worked pretty well in my first iteration for the eight vertices of K which I counted through using "allepunkte". I guess this worked because K is a normal array and not a cell array. After that I want to calculate the distances between the intersection points and my vertices of my component and compare them to each other to see whether I am inside my bounding box. My ultimate goal is to get to know that and if I am outside the bounding box, no matter in the direction of x,y,z, to get that out of Matlab as an Information. The information should tell me how much I have to move the component in the direction of x,y or z to be inside the bounding box and the after I did that do the collision check again.

My idea is now to create different Matrix M1,M2 and the use huellkoerper again to count it up in a for loop. But instead of having a cell array I am going to say if huellkoerper is 1 use M1, elseif 2 use M2 and so on. But what does that mean for my intersection points? Can I still write them into cell arrays?

The intersection points are called spx,spy,spz. Then a 1 or two to decide which one of the planes in the direction it is. SO I got spx1,spx2,spy1,spy2,spz1,spz2. Then are following the braces of the cell array. Using spx1 it would be. spx1{huellkoerper}{allepunkte}. So I want to know inside which body M I check and which of the vertices of my Component K I am checking.

As I said I am so grateful for your help everybody I am really looking forward to your response! If you have ideas how to do that easier or more intelligent it would be nice too. As I said I´m unexperienced and that is the first solution that came to my mind.

Have a nice weekend and thanks for your work in advance!

Johnny

[Walter Roberson]

Your code does not use M after the M=M{huellkoerper}; line, so it is difficult to understand how M fits with the rest of your code.

My idea is now to create different Matrix M1,M2 and the use huellkoerper again to count it up in a for loop. But instead of having a cell array I am going to say if huellkoerper is 1 use M1, elseif 2 use M2 and so on

NO! Just use M{huellkoerper} in the part of your code that you want the appropriate matrix!

[Jonathan Babitsch]

Wow you are right the solution is changing M=M{huellkorper}; to just M{huellkoerper};

So that's what you meant earlier I just wasn't getting it...

Thank you a lot Walter you are a genius! Helped me out a lot! That was a lot easier than I expected. Big thank you once again! Hope I can count on your advice if I need it again in the future.

Have a nice weekend,

Johnny

Answer 1

[Walter Roberson]

Inside a for loop, you are assigning

M = M{INDEX} 

That replaces all of M with the contents of one cell of M. Afterwards, M is unlikely to be a cell array.