# Finding A Minimum Or Maximum - HP -28S Manual

The Solver menu shows all the variables in the current equation (only
X in this example).
Store the digitized estimate in variable X.
Ijlr:=~;
iiiGffiliiB:Jii: c:::Jijij!ft)JImc:::Jti§[icr)'ic:::Jiiiiic:::Jiiiill
Although the digitized point contained two coordinates, the Solver
will use only the first coordinate as an estimate.
Now solve for X.
!P.--
{gn Reversal
1:
-1. 36
ITJGffilc:::Jc:::Jc:::Jc:::J
The message:::
i
gn Rever
s.:ll indicates that the Solver found an
approximate solution, correct to 12 digits. If the Solver found an exact
solution, it would display the message
Zet-
o. These messages, called
qualifying messages,
are discussed in HSOLVE H in the Reference
Manual.
@illl
=-:---3:
------,1
2:
1:
-1. 36
[::::[:JGffilc:::Jc:::Jc:::Jc:::J
Finding a Minimum or Maximum
To find the zero of an expression, the Solver samples points on the
graph, starting with your estimate, and tries to find points closer to
the x-axis. If your estimate is quite close to a
positive local minimum
or
a
negative local maximum,
there are no points nearby that are closer to
the x-axis. In this case, the Solver finds that extremum (minimum or
maximum) rather than a zero. (Generally the Solver won't Hget stuck"
at an extremum unless your estimate forces it there.)
~
100
8: The Solver