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Topic: data extraction from matrix to use in another matrix
Replies: 26   Last Post: Oct 22, 2013 4:57 PM

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 walter Mulvany Posts: 14 Registered: 10/19/13
Re: data extraction from matrix to use in another matrix
Posted: Oct 21, 2013 6:10 PM

I think that this problem is about indexing, and I don't think that I have done a good job explaining what I need to do.
This program is about finite element analysis of a bar element, and I have to input a number of nodes that have x,y coordinates, a number of member that have a connectivity between those nodes ( node a to node b or just columns 2 and 3 in matrix conn). Example, element 1 goes from node 5 to node 2, element 11 goes from node 6 to node 7.

What I need to do is to go to element 1, read the value of (conn - row 2) which is 5, go to the coord matrix, find the value (5) in its row 1 and extract the x value that correspond to that location (5) from (conn - row 2) which in this case is (1).

Those values can be stored in a matrix, lets call it M as you named it.
I think that the confusion came because I had the other matrices nodeax and nodeay and you probably thought that they existed as part of the input but I just put it there to show how the matrix with the coordinates look like.

conn=[1,5,2;2,2,3;3,3,4;4,4,7;5,3,7;6,3,6;7,6,2;8,5,2;9,1,5;10,5,6;11,6,7];
disp ('Elem # Node(a) Node(b)')
disp(conn)
coord=[1,0,0;2,2,0;3,4,0;4,6,0;5,1,1;6,3,1,;7,5,1];
disp ('Node # Xcoord Ycoord')
disp(coord)
M=zeros(length(conn),4);
for i=1:length(conn),
M(i,:)=[conn(i,:) conn(find(conn(:,1)==conn(i,1)),:)];
end

I apologize for all the confusion and I appreciate you effort.
Thanks.
Let me know if you need any additional information.

Date Subject Author
10/19/13 walter Mulvany
10/19/13 dpb
10/19/13 walter Mulvany
10/19/13 dpb
10/19/13 walter Mulvany
10/20/13 dpb
10/20/13 walter Mulvany
10/20/13 dpb
10/20/13 walter Mulvany
10/21/13 walter Mulvany
10/21/13 dpb
10/21/13 dpb
10/21/13 walter Mulvany
10/21/13 dpb
10/21/13 walter Mulvany
10/22/13 walter Mulvany
10/22/13 dpb
10/22/13 walter Mulvany
10/22/13 walter Mulvany
10/22/13 dpb
10/22/13 walter Mulvany
10/22/13 dpb
10/22/13 dpb
10/22/13 walter Mulvany
10/22/13 dpb
10/22/13 dpb
10/20/13 dpb