Columns with at least one zero element

Hi,

If I have a matrix with random dimension mxn , how can I detect a column which have at least one zero element?

Thank you

Answer 1

[Mischa Kim]

Anya, you could use

 A = [1 2 3 0 8; 5 0 1 2 2];
 col = find(sum(A==0))
 col =
     2     4

col shows the columns which have at least one zero.

[dpb]

Just for comparison...

>> A = [1 2 3 0 8; 5 0 1 2 2];
>> (sum(A==0))
ans =
   0     1     0     1     0
>> all(A)
ans =
   1     0     1     0     1
>> ~all(A)
ans =
   0     1     0     1     0
>>

Answer 2

[Jos (10584)]

Let M be your mxm matrix:

tf = any(M==0,1) % true for columns with at least 1 zero
C = M(:,~tf) % columns with no zeros

[Anya]

This answer also works ! thx guys

[dpb]

NB:

any(M==0) --> identically equal to ~all(M).  One rarely (if ever) needs to expressly test for zero.

See the doc for each for details...

Answer 3

[dpb]

idx=~all(M);