# simplifying kinda-eye matrix of NxN, how?

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M Adli Hawariyan on 10 Jul 2022
Commented: M Adli Hawariyan on 10 Jul 2022
greetings, here's the problem:
i have a matrix like this:
A = [cosx_X cosx_Y cosx_Z
cosy_X cosy_Y cosy_Z
cosz_X cosz_Y cosz_Z]
cosx_X = alp(d,1);cosx_Y = alp(d,2);cosx_Z = alp(d,3);
cosy_X = alp(d,4);cosy_Y = alp(d,5);cosy_Z = alp(d,6);
cosz_X = alp(d,7);cosz_Y = alp(d,8);cosz_Z = alp(d,9);
t = [cosx_X cosx_Y cosx_Z 0 0 0 0 0 0 0 0 0;
cosy_X cosy_Y cosy_Z 0 0 0 0 0 0 0 0 0;
cosz_X cosz_Y cosz_Z 0 0 0 0 0 0 0 0 0;
0 0 0 cosx_X cosx_Y cosx_Z 0 0 0 0 0 0;
0 0 0 cosy_X cosy_Y cosy_Z 0 0 0 0 0 0;
0 0 0 cosz_X cosz_Y cosz_Z 0 0 0 0 0 0;
0 0 0 0 0 0 cosx_X cosx_Y cosx_Z 0 0 0;
0 0 0 0 0 0 cosy_X cosy_Y cosy_Z 0 0 0;
0 0 0 0 0 0 cosz_X cosz_Y cosz_Z 0 0 0;
0 0 0 0 0 0 0 0 0 cosx_X cosx_Y cosx_Z;
0 0 0 0 0 0 0 0 0 cosy_X cosy_Y cosy_Z;
0 0 0 0 0 0 0 0 0 cosz_X cosz_Y cosz_Z ];
any tips for simplify the writing of matrix? any guidance will help me alot, thanks

KSSV on 10 Jul 2022
A = rand(3) ;
[m,n] = size(A) ;
iwant = zeros(4*m,4*n) ;
for i = 1:4
idx = (1:m)+(i-1)*3 ;
iwant(idx,idx)=A;
end
spy(iwant) ### More Answers (1)

Steven Lord on 10 Jul 2022
To build A from alp use reshape and transpose.
To build t from A use blkdiag.
##### 1 CommentShowHide None
M Adli Hawariyan on 10 Jul 2022
my data ALP is from loop data;
ALP = [cosx_X cosx_Y cosx_Z
cosy_X cosy_Y cosy_Z
cosz_X cosz_Y cosz_Z]
if i want to make the desired t (like answer above), how to make ALP in t is still continue? i got the answer like this; t1 is good answer, but t2 is not
for d=1:3
alp = [ 1 0 0 0 1 0 0 0 1;
1 0 0 0 1 0 0 0 1;
1 0 0 0 1 0 0 0 1]
%angle for t matrix placing
ALP = (reshape(alp(d,1:9),[3,3]))'
[m,n] = size(ALP);
t1 = zeros(4*m,4*n);
for ii = 1:4
idx = (1:m)+(ii-1)*3;
t1(idx,idx)=ALP;
end
tt = transpose(t);
t2 = blkdiag(ALP)
end
t2 answer when loop d=1:2
ALP =
1 0 0
0 1 0
0 0 1
t2 =
1
ALP =
1 0 0
0 1 0
0 0 1
t2 =
0
any suggestions? thanks alott

R2019b

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