matrix - MATLAB sub2ind using vectors -


suppose have matrix a

a = magic(5)  17    24     1     8    15 23     5     7    14    16  4     6    13    20    22 10    12    19    21     3 11    18    25     2     9

now select block of matrix using

a(1:2, 1:2)  17    24 23     5

now need linear index given (1:2, 1;2) (1 2 6 7). using sub2ind:

sub2ind(size(a),[1:2], [1:2])

but command returns (1 7) how can solve this?

suppose want select a(1:2,2:3):

% row , column indexes rind = 1:2; cind = 2:3;  pos  = bsxfun(@plus,rind', size(a,2)*(cind-1));  pos =      6    11      7    12

you might want reshape column vector pos(:), or in 1 line call reshape().


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