Deleting rows and columns of all zeroes in a symbolic matrix

Hello,

How can I delete all rows and columns of all zeroes in a symbolic matrix?

The solution listed here ( http://www.mathworks.com/matlabcentral/answers/40018-delete-zeros-rows-and-columns ) does not work when the matrix is symbolic. The any command produces an error "Unable to prove variable-name literally."

Thanks, Kevin

Answer 1

[Teja Muppirala]

syms x1
data = [ x1, 1, 0 ; 0, 0, 0 ; 0, 1, 0]
data( all( isAlways(data==0) ,2) ,:) = []
data( : ,all( isAlways(data==0) ,1)) = []

Answer 2

[Shashank Prasanna]

The following worked perfectly fine for me. Can you share the exact error message you got?

x = [1 1 0;0 0 0;0 1 0]

>> data=sym(x)

data =

[ 1, 1, 0]
[ 0, 0, 0]
[ 0, 1, 0]

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

[Kevin Bachovchin]

The difference is that your data sym doesn't have any element syms.

Try

syms x1

data = [ x1, 1, 0 ; 0, 0, 0 ; 0, 1, 0]

data( ~any(data,2), : ) = []; %rows

data( :, ~any(data,1) ) = []; %columns

and you will get an error saying "Unable to prove 'x1' literally."