MATLAB: How to update size(Matrix,1) in for loop? I am receiving the “Index exceeds matrix dimensions” error.

for loopindexmatrixsize;

I am running into an issue as I am deleting rows in a matrix. As I delete rows, size(Matrix,1) changes, and I assume that is causing an error in the for statement. The error I receive is "Index exceeds matrix dimensions." Below is my first of two attempts at the code:
 [~, ~, Matrix]=xlsread('TestEachSceneOnce.xls', 'Sheet1')
for m = 1:size(Matrix,1)
    for n=1:size(Matrix,1)
        if strcmp(Matrix(m,4),Matrix(n,4)) & Matrix{n,5}~='alreadydone' & m~=n % without m~=n, we would be checking if a cell is equal to itself 

            Matrix{n,5}='alreadydone'
            Matrix(m,:)=[]
        else  
        end
    end 
 end
xlswrite('TestEachSceneOnce.xls', Matrix, 'Sheet2')
Therefore, I tried to update size(Matrix,1) each time a row is deleted in the code below. I still get the following error: "Index exceeds matrix dimensions."
 [~, ~, Matrix]=xlsread('TestEachSceneOnce.xls', 'Sheet1')
UpdatedSizeOfMatrix=size(Matrix,1)
for m = 1:UpdatedSizeOfMatrix
    for n=1:UpdatedSizeOfMatrix
        if strcmp(Matrix(m,4),Matrix(n,4)) & Matrix{n,5}~='alreadydone' & m~=n % without m~=n, we would be checking if a cell is equal to itself 
            Matrix{n,5}='alreadydone'
            Matrix(m,:)=[]
            UpdatedSizeOfMatrix=size(Matrix,1)
        else
        end
     UpdatedSizeOfMatrix=size(Matrix,1)
    end
 end
 xlswrite('TestEachSceneOnce.xls', Matrix, 'Sheet2')
I would appreciate any help you can provide.

Best Answer

I think I answered my own question. First, I tried out looping backward (decrementing, or looping backward by -1) with a matrix:
 %TheMatrix=[1;1;2;2;3;4;3;4]
TheMatrix=[6;1;1;6;4;3;7;7]
NewSize=size(TheMatrix,1)
%i is the number of rows in the array

for i=8:-1:1
    for NewSize=NewSize:-1:1
        if i~=NewSize & TheMatrix(i)==TheMatrix(NewSize)
            OldSize=size(TheMatrix,1)
            TheMatrix(i)=[]
            TheMatrix
            NewSize=size(TheMatrix,1)
            if OldSize>size(TheMatrix,1)
              break
            end
        else
            NewSize=size(TheMatrix,1)
        end
    end
end
Then, I applied the appropriate code for a cell array:
 [~, ~, Matrix]=xlsread('TestEachSceneOnce.xls', 'Sheet1')
NewSize=size(Matrix,1)
%i is the number of rows in the array
for i=9:-1:1
    for NewSize=NewSize:-1:1
        if i~=NewSize & strcmp(Matrix{i,4},Matrix{NewSize,4})
            OldSize=size(Matrix,1)
            Matrix(i,:)=[]
            Matrix
            NewSize=size(Matrix,1)
            if OldSize>size(Matrix,1)
              break
            end
        else
            NewSize=size(Matrix,1)
        end
    end
end
xlswrite('TestEachSceneOnce.xls', Matrix, 'Sheet2')
This seems to be working. I am attaching the spreadsheet too. Thank you for your suggestion @WalterRoberson!
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