hp 28s - creating nested lists

[Werner]

Aha.. that's probably it.
The 48/49 STEP syntax specifies:

Quote:If the argument of STEP is an algebraic expression or a name, it is automatically evaluated to a number.

But the 28 accepts only a real number, not a variable holding one.
So, just add EVAL before STEP (or even better, before DUP). That should do it.

Code:

\<<
  \-> n
  \<<
    1 2 n
    FOR i
      DUPN i EVAL DUP
    STEP
    n - DUP 0 <
    { NEG DUPN }
    { DROPN }
    IFTE
    n
  \>>
\>>

Cheers, Werner