Convert tracelines into imat_elem
el=to_elem(tl)
el=to_elem(tl,idoff)
TO_ELEM processes the supplied tracelines into an IMAT_ELEM. Multi-segment tracelines are first transformed into 2-node segments, and then the tracelines are converted into 2-node rod elements. Two-node tracelines retain their IDs, and multi-node tracelines are given IDs starting with one higher than the highest ID in TL.
IDOFF is an optional scalar specifying an offset to apply to the traceline IDs.