how to obtain the number of cases of length. but those matrices sum must be 30 or something value(on constraints)

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Brian Kim 2017-9-13

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first, -constraints-

elements must be between 4 and 12

for example,

A=[6 7 8 9], sumA=sum(A)=30;

What is number of cases of length that can be obtained so that the sum becomes 30?

For reference,

If the length of the matrix is 5, A is [5 5 6 7 7].

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Stephen23 2017-9-13

编辑：Stephen23 2017-9-13

Duplicate:

https://www.mathworks.com/matlabcentral/answers/355684-i-want-to-obtain-number-of-cases-matrix-s-length-by-applying-same-sum-in-any-matrix-on-constrai

Walter Roberson 2017-9-13

Stephen, you should not close duplicate questions that have Answers unless the Answers also appear in the original location.

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KSSV 2017-9-13

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x0 = 4 ; x1 = 12 ;
x = x0:x1 ;
iwant = cell([],1) ;
count = 0 ;
for i = 1:length(x)
    A = nchoosek(x,i) ;
    thesum = sum(A,2) ;
    if any(thesum==30)
        count = count+1 ;
        iwant{count} = A(thesum==30,:) ;
    end
end

You have the possible combinations whose sum is 30 in iwant.

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KSSV 2017-9-13

You need to only provide x.....no changes required.....

Brian Kim 2017-9-13

ah~ i am sorry. i mean, some of elements can be same.

Walter Roberson 2017-9-13

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See https://www.mathworks.com/matlabcentral/fileexchange/12009-partitions-of-an-integer

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Walter Roberson 2017-9-13

If you just need to calculate the number of different ways that you can partition a number with particular (possibly repeated) integers, then see the mathematics outlined at https://math.stackexchange.com/questions/15521/making-change-for-a-dollar-and-other-number-partitioning-problems

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