HP 50g Graphing Calculator - Manual (Page 444)

Page 13-9
Θ Press L @PICT @CANCL $ to return to normal calculator display.
Notice that the slope and tangent line that you requested are listed in
the stack.
Function DOMAIN
Function DOMAIN, available through the command catalog (‚N),
provides the domain of definition of a function as a list of numbers and
specifications. For example,
indicates that between – ∞ and 0, the function LN(X) is not defined (?), while
from 0 to + ∞, the function is defined (+). On the other hand,
indicates that the function is not defined between – ∞ and -1, nor between 1
and + ∞. The domain of this function is, therefore, -1<X<1.
Function TABVAL
This function is accessed through the command catalog or through the GRAPH
sub-menu in the CALC menu. Function TABVAL takes as arguments a function of
the CAS variable, f(X), and a list of two numbers representing a domain of
interest for the function f(X). Function TABVAL returns the input values plus the
range of the function corresponding to the domain used as input. For example,