Zero insertion

We are now going to implement the box in the diagram which has an upward arrow.
The definition of the operator is the following: considering a structured signal, the output is obtained by inserting a zero between every value of the input. As far as synchronization is concerned, the signal at index 0 retains its value at index 0.
If you want to see this in terms of z-transform, the z-transform is obtained by replacing the indeterminate z by z^2.
You will code this into a function file named "zeroinsert.m" (the file extension may not show on some systems).
You will need to use the Matlab functions zeros, and size (to check whether the input is a line or column oriented vector. Also, have a look at the help for the colon ":" operator.
The solution is here.

Summary

We have implemented the following box in the diagram