How to solve Error using repmat

If C =

         0         0    0.0244         0    0.0260         0    0.0136         0         0         0
    0.1738         0         0         0         0    0.0240         0    0.0629         0         0
         0         0         0         0         0         0         0         0         0         0
         0    0.0662         0    0.0890         0         0         0         0    0.0181    0.0472

B = reshape(repmat(max(reshape(C,2,[])),C,1),size(C))

I am getting

Error using repmat
Replication factors must be a row vector of integers or integer scalars.

How to overcome it.

[Stephen23]

See original question and (working) answers here:

https://www.mathworks.com/matlabcentral/answers/373062-sharing-of-numbers-in-the-matrix

@Prabha Kumaresan: I notice that you copied my code and changed it so that it does not work anymore. What was the purpose of that change?

[Guillaume]

@Prabha

• your profile show that you've asked 94 questions and accepted 0 answers, which would mean you that either you never got a correct answer, a worrying fact, or that you don't care about rewarding people who help you, in which case why should we bother?
• Looking at a few of your questions they barely include enough information to be able to answer you. There's no explanation of what you're trying to do, just some random code that doesn't work. Spend more time on your question
• More importantly, spend more time understanding the answers you've given and spend more time learning matlab. Read the documentation of each function used in the answers you're given and understand how the answer works.

[Prabha Kumaresan]

since i am unable to get the result i am asking again.

Answer 1

[Walter Roberson]

Your repmat call is

repmat(max(reshape(C,2,[])),C,1)

The part

max(reshape(C,2,[]))

tells MATLAB to start by reshape C to 2 rows, then find the maximum per column, giving a row vector (of 20 elements).

Then the repmat( max(...), C, 1)

tells it to repeat the vector C times along the rows. But C is floating point numbers.

Considering that you reshaped C to 2 x N, and took the max along columns to get 1 x N, in order for the reshape() you are about to do after this to work, you would need to repeat by 2:

    repmat(max(reshape(C,2,[])),2,1)

[Prabha Kumaresan]

if C =

         0         0         0         0         0    0.0086    0.0061         0    0.0039         0
    0.0106         0         0    0.0143    0.0272         0         0         0         0         0
         0         0    0.0030         0         0         0         0    0.0035         0         0
         0    0.0003         0         0         0         0         0         0         0    0.0002

I want to have output such that the first two rows should have same values and last two rows should have same values.

[Prabha Kumaresan]

if i am having (m*n) array then how repmat can be used.

[Stephen23]

@Prabha Kumaresan: by reading the repmat documentation, and correctly applying it to your array.

[Guillaume]

how repmat can be used

To do what?

Again, give a lot more details about what you want to achieve

[Prabha Kumaresan]

This was the coding which i am trying to solve siz = size(G) idx = sub2ind(siz, randi([1,10], 1, siz(2)), 1:siz(2)); C = zeros(siz); C(idx) = G(idx)

where C and G are attached as image below.

G and C are matrix of (Number of users,Number of subcarriers),(10*50)

I need to do random user grouping such that subcarriers of the grouped users need to get shared.

for that experts told me to use B = reshape(repmat(max(reshape(C,2,[])),C,1),size(C))

(or)

[ii,jj] = find(C) B = C B(sub2ind(size(C),rem(ii + 1,4)+1,jj)) = C(C>0)

But i am unable to get the result.Please help me to get out of this issue.

[Stephen23]

"experts told me to use B = reshape(repmat(max(reshape(C,2,[])),C,1),size(C))"

I can't find that particular code anywhere in the original question. Can you please provide a link to this ?

I did find my (working) code that is very similar to this, but clearly you have changed it and have so far not offered any reason for that change.

[Prabha Kumaresan]

the code which u gave worked separately for an array.but when i tried to implement on my code it doesnt work.

[Stephen23]

" i tried to implement on my code it doesnt work"

It worked when I tried it using the data that you provided.

Answer 2

[Stephen23]

>> B = reshape(repmat(max(reshape(C,2,[])),2,1),size(C))
ans =
 0.17380   0.00000   0.02440   0.00000   0.02600   0.02400   0.01360   0.06290   0.00000   0.00000
 0.17380   0.00000   0.02440   0.00000   0.02600   0.02400   0.01360   0.06290   0.00000   0.00000
 0.00000   0.06620   0.00000   0.08900   0.00000   0.00000   0.00000   0.00000   0.01810   0.04720
 0.00000   0.06620   0.00000   0.08900   0.00000   0.00000   0.00000   0.00000   0.01810   0.04720

[Stephen23]

@Prabha Kumaresan: note that this is exactly the same as my answer to your earlier question, whose code you copied and changed (without any obvious reason).

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