functions in matrices

What you show is a completely different situation!
For instance is q.c;tip a FUNCTION and NOT A VECTOR, so you can't index it with the range variabe i.n. Thats what the error message tries to tell you. You can often trace back an error to its root using the the tracing option on the calculation ribbon.

To achieve what you possibly try to do, you may use

Here looping through the values in the z and q.cza vectors is done using the range variable i.n.

But you can also do it without that range variable. With the following approach the looping is achieved using vectorization:

A third approach uses an explicit programmed for-loop to do the job. A bit more space consuming but maybe also a bit clearer to read and understand:

So you have the choice 😉

Prime 9 sheet attached