How to extract rows which contains a specific value in each row.

How to extract rows which contains a specific value in each row. Example: a =

    1.    2.    3.  
    4.    5.    6.  
    1.    2.    3.  
    4.    5.    6.

a(a==1,:)

    1.    2.    3.  
    1.    2.    3.
but the problem is as follows:
a(a==5,:)
Invalid index.

Answer 1

[Stephen23]

You need to use any:

>> a(any(a==1,2),:)
ans =
   1   2   3
   1   2   3
>> a(any(a==5,2),:)
ans =
   4   5   6
   4   5   6

[slimani djamel]

If i have a large matrix and i don't know how many rows which contain the value 5, how i can use the function any.

[Stephen23]

@slimani djamel: exactly like I showed you. It does not matter how many rows there are. Did you try it?

Answer 2

[slimani djamel]

Thanks to KSSV and Stephen Cobeldick for help.