building a diagonal matrix from another matrix!

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Hossein 2014-3-7

回答： Jos (10584) 2014-3-7

Hi eveybody,

im trying to build a diagonal matrix from another matrix in general form like following:

A=[a b,c d] -----> B[a 0 0 0,0 b 0 0,0 0 c 0,0 0 0 d]

dont want to write each array using blkdiag( ) function becuase my aimed matrix is too big.

tnx

Jos (10584) 2014-3-7

What are a,b,c, and d? scalars or matrices?

What do you mean by "too big"? Did you consider using sparse storage using, for instance, SPDIAGS?

Jos (10584) 2014-3-7

A = 1:5 ;
B_sparse = spdiags(A(:),0,numel(A),numel(A))
B_full = diag(A)
isequal(full(B_sparse),B_full)

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