MATLAB: Deleting Rows of a Matrix

cell arraysfor loopmatricesmatrixrows removalstruct

Hello,
I have a 1D matrix or an array, I have attached files.
I have to delete its rows, such that starting from 4 till 6, then 10 to 12, then 16 till 18 and so on…
so basically leave three and then delete three.. leave 1 2 3 delete 4 5 6 then leave 7 8 9 delete 10 11 12… and going on till the last of matrix
I made this small program.
The problem I am having is in defining the variable X which tells how long will this loop run for until all the required rows are deleted.
load('Mass_Global.mat')
load('Damp_Global.mat')
load('Stiffness_Global.mat')
[V,D] = eigs(Stiffness_Global,Mass_Global,1,'smallestabs')
X = 
 a =4;
for i =1:1:X
    for j =a:1:(a+2)
        V(j,: )=[];    
    end
    a = a+4
end
Does anyone has an idea?
Can it be done without loops?

Best Answer

Here's one way:
v = rand(1, 1512)' % Create sample data.
m = reshape(v, 3, []) % Make into matrix.
m(:, 2:2:end) = []; % Delete every other column.
v2 = m(:); % Turn into column vector.
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