Matrices

For the special case of two vectors you could use something like this

This works as long as the original vectors do not contain any NaN's.

A more generic approach is the use of submatrix. But I would rather apply it to the result and not to the input vectors.

Problem with submatrix is that it needs some special treatment if you want to omit the very first or the very last row.

So it would be beneficial to use a utility function which deletes any row from an arbitrary matrix.

Unfortunately you don't explain why you would want to omit a specific row. 

If you want to omit a specific row because this would throw an error like in

the aforementioned  methods will not work and it would be necessary to omit the offending row before applying the operation.

Using the utility function shown above this could be done that way: