'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

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