How can I make this matrix ?

Answer 1

[Voss]

% your matrix:
i = 0; m  = 1; j = 2; n = 3;
M = repmat([i i i m m j j j n n],4,1)

M = 4×10

0 0 0 1 1 2 2 2 3 3 0 0 0 1 1 2 2 2 3 3 0 0 0 1 1 2 2 2 3 3 0 0 0 1 1 2 2 2 3 3

% delete columns 4-5 and 9-10:
M(:,[4 5 9 10]) = []

M = 4×6

0 0 0 2 2 2 0 0 0 2 2 2 0 0 0 2 2 2 0 0 0 2 2 2

[Sourasis Chattopadhyay]

How can i mak it in a loop for (m*n) matrix?

[Voss]

Why do you want to do that?

[Sourasis Chattopadhyay]

Because my matrix size is not fixed. But every time I need to delete two column after the equal number of column interval.

[Voss]

Suppose you want to delete columns 4, 9, 14, ... and columns 5, 10, 15, ...

M = reshape(1:100,4,[])

M = 4×25

1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 65 69 73 77 81 85 89 93 97 2 6 10 14 18 22 26 30 34 38 42 46 50 54 58 62 66 70 74 78 82 86 90 94 98 3 7 11 15 19 23 27 31 35 39 43 47 51 55 59 63 67 71 75 79 83 87 91 95 99 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 80 84 88 92 96 100

spacing = 5;
N_Cols = size(M,2);

col_to_delete = [4:spacing:N_Cols 5:spacing:N_Cols];

M(:,col_to_delete) = []

M = 4×15

1 5 9 21 25 29 41 45 49 61 65 69 81 85 89 2 6 10 22 26 30 42 46 50 62 66 70 82 86 90 3 7 11 23 27 31 43 47 51 63 67 71 83 87 91 4 8 12 24 28 32 44 48 52 64 68 72 84 88 92

No loop necessary.