'root' is a Mathacd function, associated with TOL, as well a Maple function.
It can be used to inverse a function in Smath, though not in the f(x) menu.
This document illustrates its use wrt the XFR of a mutistage time constant
process system. The other example, published few weeks ago, exemplifies the
Pt100 temperature thermometer [visit "Samples"].

Jean

Inst_XFR root solve.sm (25 KiB) downloaded 61 time(s).