If I have 512 matrices (entries of each matrix is looping modulo 2), how the multiplication syntax for those 512*512 matrices ?

this is syntax for define the 512 matrices

clc,clear;

i=0;

modulo=2;

for A=1:modulo

for B=1:modulo

for C=1:modulo

for D=1:modulo

for E=1:modulo

for F=1:modulo

for G=1:modulo

for H=1:modulo

for I=1:modulo

M=[A-1 B-1 C-1 ; D-1 E-1 F-1 ; G-1 H-1 I-1];

i=i+1;

end

end

end

end

end

end

end

end

end

i

[Torsten]

If I have 512 matrices (entries of each matrix is looping modulo 2), how the multiplication syntax for those 512*512 matrices ?

Why 512x512 matrices ? You only have 512 of them.

If you multiply the 512 matrices in arbitrary order, you get the 3x3 zero matrix because one of the 512 matrices is the 3x3 zero matrix.

[Regita Agustin Wahyu F]

i wanna know how the result will be if 512 matrices are multiplied by each itself. next i'll get 262.144 matrices

[Torsten]

You mean

m = 9;
justRows = dec2bin(0:2^m-1)-'0';
n = size(justRows,1);
for i = 1:n
    A = reshape(justRows(i,:),[3,3]);
    M{i} = A;
end
for i=1:n
    for j=1:n
        MM{(i-1)*n+j} = M{i}*M{j};
    end
end

?

[Regita Agustin Wahyu F]

i got error for that syntax

[Torsten]

On my PC, it works fine.

Maybe you changed "m" ?

Then you also have to change the size of the reshaped matrix accordingly:

A = reshape(justRows(i,:),[sqrt(m),sqrt(m)]);

If the error persists, include the code you are using together with the exact error message you receive.

Answer 1

[Torsten]

m = 9;
justRows = dec2bin(0:2^m-1)-'0';
for i = 1:size(justRows,1)
    A = reshape(justRows(i,:),[3,3]);
    M{i} = A;
end

[Regita Agustin Wahyu F]

i got like this

[Walter Roberson]

How did you initialize M, or how did you ensure that you did not have any old M variable hanging around interfering with the new calculation?

[Regita Agustin Wahyu F]

do you have another idea for this case maybe ? i'm really don't understand

[Torsten]

As I see from your screenshot, you still work with your own nested loop solution before you inserted my code lines.

This is wrong because your code defines M as a numerical matrix.

Only use my 6 lines of code:

m = 4;
justRows = dec2bin(0:2^m-1)-'0';
M = cell(2^m,1); 
for i = 1:size(justRows,1)
    A = reshape(justRows(i,:),[sqrt(m),sqrt(m)]);
    M{i} = A;
    disp(M{i})
end

     0     0
     0     0

     0     0
     0     1

     0     1
     0     0

     0     1
     0     1

     0     0
     1     0

     0     0
     1     1

     0     1
     1     0

     0     1
     1     1

     1     0
     0     0

     1     0
     0     1

     1     1
     0     0

     1     1
     0     1

     1     0
     1     0

     1     0
     1     1

     1     1
     1     0

     1     1
     1     1

[Torsten]

m = 4;
justRows = dec2bin(0:2^m-1)-'0';
n = size(justRows,1);
M = cell(2^m,1);
for i = 1:n
    A = reshape(justRows(i,:),[sqrt(m),sqrt(m)]);
    M{i} = A;
end
MM = cell(n^2,1);
for i=1:n
    for j=1:n
        MM{(i-1)*n+j} = M{i}*M{j};
        disp(MM{(i-1)*n+j})
    end
end

     0     0
     0     0

     0     0
     0     0

     0     0
     0     0

     0     0
     0     0

     0     0
     0     0

     0     0
     0     0

     0     0
     0     0

     0     0
     0     0

     0     0
     0     0

     0     0
     0     0

     0     0
     0     0

     0     0
     0     0

     0     0
     0     0

     0     0
     0     0

     0     0
     0     0

     0     0
     0     0

     0     0
     0     0

     0     0
     0     1

     0     0
     0     0

     0     0
     0     1

     0     0
     1     0

     0     0
     1     1

     0     0
     1     0

     0     0
     1     1

     0     0
     0     0

     0     0
     0     1

     0     0
     0     0

     0     0
     0     1

     0     0
     1     0

     0     0
     1     1

     0     0
     1     0

     0     0
     1     1

     0     0
     0     0

     0     1
     0     0

     0     0
     0     0

     0     1
     0     0

     1     0
     0     0

     1     1
     0     0

     1     0
     0     0

     1     1
     0     0

     0     0
     0     0

     0     1
     0     0

     0     0
     0     0

     0     1
     0     0

     1     0
     0     0

     1     1
     0     0

     1     0
     0     0

     1     1
     0     0

     0     0
     0     0

     0     1
     0     1

     0     0
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     0     1
     0     1

     1     0
     1     0

     1     1
     1     1

     1     0
     1     0

     1     1
     1     1

     0     0
     0     0

     0     1
     0     1

     0     0
     0     0

     0     1
     0     1

     1     0
     1     0

     1     1
     1     1

     1     0
     1     0

     1     1
     1     1

     0     0
     0     0

     0     0
     0     0

     0     0
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     0     0
     1     0

     0     0
     1     0

     0     0
     1     1

     0     0
     1     1

     0     0
     1     0

     0     0
     1     0

     0     0
     1     1

     0     0
     1     1

     0     0
     0     0

     0     0
     0     1

     0     0
     0     1

     0     0
     0     2

     0     0
     1     0

     0     0
     1     1

     0     0
     1     1

     0     0
     1     2

     0     0
     1     0

     0     0
     1     1

     0     0
     1     1

     0     0
     1     2

     0     0
     2     0

     0     0
     2     1

     0     0
     2     1

     0     0
     2     2

     0     0
     0     0

     0     1
     0     0

     0     0
     0     1

     0     1
     0     1

     1     0
     0     0

     1     1
     0     0

     1     0
     0     1

     1     1
     0     1

     0     0
     1     0

     0     1
     1     0

     0     0
     1     1

     0     1
     1     1

     1     0
     1     0

     1     1
     1     0

     1     0
     1     1

     1     1
     1     1

     0     0
     0     0

     0     1
     0     1

     0     0
     0     1

     0     1
     0     2

     1     0
     1     0

     1     1
     1     1

     1     0
     1     1

     1     1
     1     2

     0     0
     1     0

     0     1
     1     1

     0     0
     1     1

     0     1
     1     2

     1     0
     2     0

     1     1
     2     1

     1     0
     2     1

     1     1
     2     2

     0     0
     0     0

     0     0
     0     0

     0     1
     0     0

     0     1
     0     0

     0     0
     0     0

     0     0
     0     0

     0     1
     0     0

     0     1
     0     0

     1     0
     0     0

     1     0
     0     0

     1     1
     0     0

     1     1
     0     0

     1     0
     0     0

     1     0
     0     0

     1     1
     0     0

     1     1
     0     0

     0     0
     0     0

     0     0
     0     1

     0     1
     0     0

     0     1
     0     1

     0     0
     1     0

     0     0
     1     1

     0     1
     1     0

     0     1
     1     1

     1     0
     0     0

     1     0
     0     1

     1     1
     0     0

     1     1
     0     1

     1     0
     1     0

     1     0
     1     1

     1     1
     1     0

     1     1
     1     1

     0     0
     0     0

     0     1
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     0     1
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     0     2
     0     0

     1     0
     0     0

     1     1
     0     0

     1     1
     0     0

     1     2
     0     0

     1     0
     0     0

     1     1
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     1     1
     0     0

     1     2
     0     0

     2     0
     0     0

     2     1
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     2     1
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     2     2
     0     0

     0     0
     0     0

     0     1
     0     1

     0     1
     0     0

     0     2
     0     1

     1     0
     1     0

     1     1
     1     1

     1     1
     1     0

     1     2
     1     1

     1     0
     0     0

     1     1
     0     1

     1     1
     0     0

     1     2
     0     1

     2     0
     1     0

     2     1
     1     1

     2     1
     1     0

     2     2
     1     1

     0     0
     0     0

     0     0
     0     0

     0     1
     0     1

     0     1
     0     1

     0     0
     0     0

     0     0
     0     0

     0     1
     0     1

     0     1
     0     1

     1     0
     1     0

     1     0
     1     0

     1     1
     1     1

     1     1
     1     1

     1     0
     1     0

     1     0
     1     0

     1     1
     1     1

     1     1
     1     1

     0     0
     0     0

     0     0
     0     1

     0     1
     0     1

     0     1
     0     2

     0     0
     1     0

     0     0
     1     1

     0     1
     1     1

     0     1
     1     2

     1     0
     1     0

     1     0
     1     1

     1     1
     1     1

     1     1
     1     2

     1     0
     2     0

     1     0
     2     1

     1     1
     2     1

     1     1
     2     2

     0     0
     0     0

     0     1
     0     0

     0     1
     0     1

     0     2
     0     1

     1     0
     0     0

     1     1
     0     0

     1     1
     0     1

     1     2
     0     1

     1     0
     1     0

     1     1
     1     0

     1     1
     1     1

     1     2
     1     1

     2     0
     1     0

     2     1
     1     0

     2     1
     1     1

     2     2
     1     1

     0     0
     0     0

     0     1
     0     1

     0     1
     0     1

     0     2
     0     2

     1     0
     1     0

     1     1
     1     1

     1     1
     1     1

     1     2
     1     2

     1     0
     1     0

     1     1
     1     1

     1     1
     1     1

     1     2
     1     2

     2     0
     2     0

     2     1
     2     1

     2     1
     2     1

     2     2
     2     2

[Regita Agustin Wahyu F]

Do you mean like this ?

[Torsten]

As you can see above, both codes work with MATLAB R2022a.

I don't know which MATLAB version you have installed and what code lines "coba2" might contain that predefine the cell array M somehow.

I suggest you quit MATLAB and restart it.

Predefining M and MM as

M = cell(2^m,1)

MM = cell(n^2,1)

might help (see above).

[Regita Agustin Wahyu F]

thankyou sir, the last code above finally works in my matlab, but i wanna ask you, does the code above for 16*16=256 matrices ?

[Torsten]

The matrices M and MM are sqrt(m) x sqrt(m) - matrices. So you can change "m" appropriately.

[Regita Agustin Wahyu F]

ok thx sir. But can i make MM{(i-1)*n+j} = M{i}*M{j} times MM{(i-1)*n+j} = M{i}*M{j} ? with each MM{(i-1)*n+j} = M{i}*M{j} = 256 matrices if m = 4 as your code above. So later i'll get 65.536 matrices. I'm still confuse how to change the function

[Torsten]

I don't understand what you are asking.

Given m, you get 2^m matrices M and 2^(2*m) matrices MM.

So if m = 4, you get 16 matrices M and 256 matrices MM

If m = 9, you get 512 matrices M and 262144 matrices MM.

If m = 16, you get 65536 matrices M and 4294967296 matrices MM. But I doubt you have sufficient RAM to do that.