No. It is obvious that one or more of the elements are not scalar. Please try:
dbstop if error
Then run your code again until it stops with the error message. Then type in the command window:
size(u)
size(uc)
size(y)
size(yc)
size(d)
This procedure is called "debugging" and it is even more powerful than this forum.
It is pure guessing only, but in some fonts the "1" (one) looks like a "l" (lowercase L), so please check if there is really a one in "yres(1)". General rule: Never use l (lowercase L) and O (uppercase oh) as names.
