Deleting row and column with all zeros and putting it back

Hell0,

I am trying to perform an operation on a big Matrix (within a cell). Here,

B=

   -17.5310 +20.7302i   0.0000 + 0.0000i   5.4364 - 2.0952i
     0.0000 + 0.0000i   0.0000 + 0.0000i   0.0000 + 0.0000i
     5.4364 - 2.0952i   0.0000 + 0.0000i -17.5310 +20.7302i

so, I used this,

data=B{1,1};
 data( ~any(data,2), : ) = [];  %rows
data( :, ~any(data,1) ) = [];  %columns
data2=data;

This deletes the rows and columns with all zeros and returns me this,

data2=

   -17.5310 +20.7302i   5.4364 - 2.0952i
     5.4364 - 2.0952i -17.5310 +20.7302i

then, I inverse the matrix and get my desired matrix. But, after that, I want to put back the deleted rows and column to its original places. How can I do that?

Answer 1

[Matt J]

Another solution would be to never remove them in the first place

data=B{1,1}; data2=data;

r=any(data,2);
c=any(data,1);

data2(r,c)=inv(data(r,c));

Answer 2

[Rik]

B={[-17.5310+20.7302i   0.0000+0.0000i   5.4364-2.0952i
    0.0000+0.0000i   0.0000+0.0000i   0.0000+0.0000i
    5.4364-2.0952i   0.0000+0.0000i -17.5310+20.7302i]};
data=B{1,1};
keep_rows=any(data,2);
data( ~any(data,2), : ) = []; %rows
keep_cols=any(data,1);
data( :, ~any(data,1) ) = []; %columns
data2=data;

%do whatever you need to do with the data2 matrix

data3a=zeros(size(data2,1),numel(keep_cols));
data3a(:,keep_cols)=data2;%undo removing of cols
data3=zeros(numel(keep_rows),numel(keep_cols));
data3(keep_rows,:)=data3a;%undo removing of rows

Answer 3

[Birdman]

One workaround could be(Consider your B is double array, extracted from the cell):

r=all(B==0,2);
c=all(B==0,1);
B(r,:)=[];
B(c,:)=[];
%do your calculation
B(:,find(c)+1)=B(:,c)
B(find(r)+1,:)=B(r,:)
B(:,c)=0+0j;
B(r,:)=0+0j