Tag; Could you explain how it works?

Question

Let?s say, I have dozen of elements (floating point numbers) in a 1-D array. I am planning to do mathematical manipulation and sort it later.
However, I have to keep track of where all the elements have placed.
I wish to add tag to each element in the array such that I know where every element is after sorting. How do you assign tag and retrieve the tag?
After assigning the tag, does it still keep the same type as floating point?
Or I can patiently keep track of every element in multidimensional array, I guess?..

Answer 1

Yes, sir! You are absolutely right.
However, if you are familiar with Don Kanuth's shuffling algorithm which assign random number tag to the sequential deck of card and sort the random number which will shuffle the deck. I am browing the concept and try to implement such idea on my boring and lengthy computation.