HP 50g Graphing Calculator - Manual (Page 784)

Page 27-2
7. For each known variable, type its value and press the corresponding menu
key. If a variable is not shown, press L to display furth er variables.
8. Optional: supply a guess for an unknown variable. This can speed up the
solution process or help to focus on one of several solutions. Enter a guess
just as you would the value of a known variable.
9. Press ! followed by the menu key of the variable for which you are
solving. If you want to solve all the equations in the selected title, press !
##ALL#. The Solver then calculates values for all the variables not previously
defined by you.
Using the Solver
When you select a subject and a title in the Equation Library, you specify a set
or one or more equations. Then, when you press
#SOLV# , you leave the Equation
Library catalogs and start solving the equations you’ve selected.
When you press #SOLV# in the Equation Library, the application does the
following:
The set of equations is stored in the appropriate variable: EQ for one
equation, EQ and Mpar for more than one equation. (Mpar is a reserved
variable used by the Multiple-Equation Solver.) Note: because EQ and
Mpar are variables, you can have a different EQ and Mpar for each
directory in memory.
Each variable is created and set to zero unless it already exists. (If the
variable name has been used by the solver before, then it is a global
variable and therefore already exists: until you purge it.)
Each variable’s units are set to the conditions you specified: SI or English,
and units used or not used—unless the variable already exists and has units
dimensionally consistent with what you specified. (To change from English
to SI units or vice versa, you must first purge the existing variables or
explicitly enter the units with the values.)
The appropriate solver is started: the SOLVR for one equation, the Multiple-
Equation Solver for more than one equation.