how to pick element by element

A = magic(3)

kindly tell me how i can pick one by one element in same matrix A then do some mathematical operation if it satisfies the condition the element is replaced by new value else it remains the same for example mathematical operation is A + 10, if A+10 is >12 replace other wise remain same as initial value,then second then third..........

thanks

[Stephen23]

What operation do you wish to perform?

[Offroad Jeep]

I am trying to simulate ferromagnet in which i think this logic will be helpful in flipping the moments

Answer 1

[Stephen23]

Why not just use logical indexing:

>> A = magic(3)
A =
   8   1   6
   3   5   7
   4   9   2
>> A(A>3) = 0
A =
   0   1   0
   3   0   0
   0   0   2