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onako 29Jul2010 19:10

Matrix Transpose
 
I store matrix entries in std::vector<double>, such that the reading is row by row.
This means, for matrix
1 3 4 8 9 3
3 6 8 1 1 2
2 0 9 8 7 6

the std::vector<double> would have entries: {1,3,4,8,9,3,3,6,8,1,1,2,2,0,9,8,7,6}.
To transpose the matrix I use the naive approach of iterating through std::vector, calculating for each
entry its position in a matrix transpose. Recently, I got one suggestion:

"When you have a matrix and a mapping to a one-dimensional vector, transposing is equivalent to a permutation. Now execute this permutation by sorting the elements by requested rank in the permutation result."

I understand that transposing is equivalent to a permutation, but I dont know how to approach the problem this way.
Any suggestion on how to do this (or to do matrix transpose is a faster way) is welcome.
--- I understand it is C++ specific (according to the description), but it is general programming problem. Thanks

shabbir 29Jul2010 19:33

Re: Matrix Transpose
 
Duplicate of Matrix Transpose. Thread closed.


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