@sundar This has to do with how if (? in MATL) is evaluated. If you pass an array as the condition of an if, it only evaluates to true if ALL elements of the array are non-zero. Since d yields [-3 6 -6 0], this will evaluate to false causing the ZS to never be evaluated

Oh also just realized you figured out on your own :)

Yeah :) Figured it out and posted this answer.