# Multiplication of sparse matrix and a normal matrix

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Amit Chakraborty 2021 年 9 月 25 日

I have a Sparse Matrix : S
The size of S is : 196608x4096 sparse double
and the normal (Non Sparse) matrix : D
The size of D is : 196608x1 single
Matrix D is full of one . [ means : D= ones(196608,1 )]
I want to multiply them both >> transpose(S)* D;
But showing me some error :
1. " Error using .* Sparse single array arithmetic operations are not supported."
2. " Error using * MTIMES (*) is not supported for one sparse argument and one single argument "
Even I tried to convert the matrix D into sparse but showing me following error :
" Error using sparse Input matrix must be double or logical".
Any kind of suggestions to solve this problem will be appreciated.
Thank You !!!
Happy Weekend !!!

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### 採用された回答

Walter Roberson 2021 年 9 月 25 日
You are trying to multiply a sparse double precision matrix by a non-sparse single precision matrix.
If you are expecting:
• sparse double result: use S.' * double(D)
• sparse single result: not permitted. sparse matrices can only be double precision or logical
• full double result: use full(S.' * double(D))
• full single result: use full(S.' * D)

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### その他の回答 (2 件)

David Goodmanson 2021 年 9 月 25 日
Hi Amit,
sum(S)'
where the result is still sparse, or
full(sum(S)')
if you want a regular vector at that point.
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Amit Chakraborty 2021 年 9 月 25 日
I do not want to convert into "full". Because above matrix is just example. Converting into "full" will takes lot of memory.

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Amit Chakraborty 2021 年 9 月 25 日
Thank you Both. I have learnt a new thing from you guys.

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