I have a nxn matrix(A) which has many zero rows and zero columns.. I removed the zero rows and columns using the command below such that Anew is now (n-m) x (n-m). After some computations on Anew matrix, I need to get Anew matrix back to nxn matrix.

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SanthoshKumar C
SanthoshKumar C 2018-1-25
回答： SanthoshKumar C 2018-1-26
I am removing the zero rows and zero columns from my matrix A using the command:
Anew=A(any(A,2),any(A,1)) ;where A(nxn) and Anew((n-m)x(n-m)) where there are m zero rows/columns
After some computation on Anew, I need to add the zero rows and columns back to their original position so that Anew now becomes nxn..
How to do it? Please help

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采纳的回答

James Tursa
James Tursa 2018-1-25
temp = A;
temp(any(A,2),any(A,1)) = Anew;
Anew = temp;
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SanthoshKumar C
SanthoshKumar C 2018-1-26
Ur posted code will give Anew matrix of size nxn. But what I need is lil different.
Ex:
A=[1 0 2 0 3; 0 0 0 0 0; 4 0 5 0 6; 0 0 0 0 0; 7 0 8 0 9];
After the step,
Anew=A(any(A,2),any(A,1)) ;
Anew =
1 2 3
4 5 6
7 8 9
Now I am doing some computation on Anew such that modified Anew will be as follows:
Anew = Anew+5
Anew =
6 7 8
9 10 11
12 13 14
Last step: (Need to do this now) . Insert the zero rows and columns back to the original position in Anew such that Anew looks like this
Anew =
6 0 7 0 8
0 0 0 0 0
9 0 10 0 11
0 0 0 0 0
12 0 13 0 14
SanthoshKumar C
SanthoshKumar C 2018-1-26
Since I am working on matrix inverse of a (300+)x(300+) matrix which can have a more number of zero rows and columns (ill-conditioned matrix ofcourse).. Need robust way to do this

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SanthoshKumar C
SanthoshKumar C 2018-1-26
Thanks James Tursa.. I overlooked your answer.. Its working

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