Is there a function/command call that does 2-d logical

Given for example a = rand(3,3) I want to keep only those entries in a that are greater than say 0.5. How to do this?

I've tried a(a>0.5), but it only gave the values as a vector, not the values situated on where they WERE in a.

Answer 1

[Stephen23]

Either you can get a vector of only the values that you want (like you were getting), or you can have a matrix by replacing the unwanted values with some value/s of your choice, e.g.:

a = rand(3,3)
a(a<=0.5) = NaN

It is not possible to have a matrix with "holes" in it. Every element of your matrix must contain a value.

Answer 2

[madhan ravi]

 a = rand(3)
 logicals=a>0.5 %tells where they are located in matrix
 values=a(logicals)