how to multiply every single element in a matrix to entire of another matrix?

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?

Answer 1

[Paul]

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)

S = 5x5 cell array
    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}
    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}
    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}
    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}
    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}

% check
S{1,1} - x(1,1)*z

ans = 2x2

0 0 0 0

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S{3,3} - x(3,3)*z

ans = 2x2

0 0 0 0

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[majid]

thank you for your answering.

Is there any way to save these cells seperately in seperate indexed S?

[Paul]

I'm afraid I don't understand. S is a cell array and each cell can be accessed by cell indexing.

Do you want to save each result in separate variables that use a naming scheme to identify the result, like S11, S12, S13 and so on? If so, that's almost always, if not actually always, a bad idea.

Otherwise, I don't know the meaning of "separate indexed S".

[DGM]

https://www.mathworks.com/matlabcentral/discussions/tips/849901-tutorial-why-variables-should-not-be-named-dynamically

[Stephen23]

"Is there any way to save these cells seperately in seperate indexed S?"

That is exactly what they are.

You can trivially use indexing to access the separate arrays stored in the cell array S:

https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-cell-array.html

[Bruno Luong]

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)

S = 5x5 cell array
    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}
    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}
    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}
    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}
    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}

[majid]

thank you for guiding me.

Answer 2

[Steven Lord]

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))

ans = logical
   1

[majid]

thankyou for answering.

Answer 3

[Bruno Luong]

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))

C = 5x5 cell array
    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}
    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}
    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}
    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}
    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}    {2x2 double}

[majid]

thankyou for answering .