how to multiply every single element in a matrix to entire of another matrix?
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Hello.
I want to multiply every single element in a matrix to entire of another matrix.
x = [100,500,900,1300,1700;
120,600,1080,1560,2040;
140,700,1260,1820,2380;
160,800,1440,2080,2720;
180,900,1620,2340,3060];
z = rand (4,20);
I want to multiply 100 to entire z and then 500 and so on... but when each multipication occured saved it in new indexed parameter.
how can I do this?
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Accepted Answer
Paul
on 7 Apr 2024
Here's one option to store each result in a cell array that's the same size as x
x = [100,500,900,1300,1700;
120,600,1080,1560,2040;
140,700,1260,1820,2380;
160,800,1440,2080,2720;
180,900,1620,2340,3060];
%z = rand (4,20);
z = [1 2;3 4]; % small z for example
S = cellfun(@(x) x*z,mat2cell(x,ones(1,size(x,1)),ones(1,size(x,2))),'Uni',false)
% check
S{1,1} - x(1,1)*z
S{3,3} - x(3,3)*z
6 Comments
Bruno Luong
on 7 Apr 2024
Edited: Bruno Luong
on 7 Apr 2024
Shorter
x = [100,500,900,1300,1700;
120,600,1080,1560,2040;
140,700,1260,1820,2380;
160,800,1440,2080,2720;
180,900,1620,2340,3060];
%z = rand (4,20);
z = [1 2;3 4]; % small z for example
S = arrayfun(@(xij) xij*z,x,'Uni',false)
More Answers (2)
Steven Lord
on 7 Apr 2024
If you're asking can you dynamically create variables with numbered names like x1, x2, x3, etc.? Yes.
Should you do this? The general consensus is no. That Discussions post explains why this is generally discouraged and offers several alternative approaches.
One such approach is to use pages of a 3-dimensional array.
x = [100,500,900,1300,1700;
120,600,1080,1560,2040;
140,700,1260,1820,2380;
160,800,1440,2080,2720;
180,900,1620,2340,3060];
z = rand (4,20);
zv = reshape(z, 1, 1, []);
result = x.*zv;
To check:
isequal(result(:, :, 42), x.*z(42))
Bruno Luong
on 7 Apr 2024
Edited: Bruno Luong
on 7 Apr 2024
x = [100,500,900,1300,1700;
120,600,1080,1560,2040;
140,700,1260,1820,2380;
160,800,1440,2080,2720;
180,900,1620,2340,3060];
%z = rand (4,20);
z = [1 2;3 4]; % small z for example
[mx,nx] = size(x);
[mz,nz] = size(z);
C = mat2cell(kron(x,z),repelem(mz,mx),repelem(nz,nx))
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