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# solvers

```These products have solvers.  The types of solvers are explained in
detail below.

-80A	TVM4
-70A	TVM4
-22A	TVM4
-27A	TVM4
-25C	TVM4
-92A	TVM5
-38E	TVM5
-34C	root finder, numerical integrator
-37E	TVM5
-38C	TVM5
-12C	TVM5
-15C	root finder, numerical integrator
-18C	algebraic
-28C	RPL28
-17B	algebraic
-19B	algebraic, w/LG
-27S	algebraic, w/LG
-28S	RPL28
-22S	alg22
14B	TVM5 (plus additional pre-programmed equations)
-42S	RPN42
-10B	TVM5
17BII	algebraic, w/LG
19BII	algebraic, w/LG
48SX	RPL48
32SII	RPN32
48S	RPL48
48G	RPL48
48GX	RPL48
38G	equation
38G+	equation
48G+	RPL48
49G	RPL48
30S
39G
40G
10Bii	TVM5
9G	??
9S	??
12CPt	TVM5
49G+	RPL48, TVM5
17BII+	??
33S	RPN32
39G+	HP Solve
48GII	??
19BII+	??
40GS
12CPA	TVM5
39GS	??
50G	??
35s	?

------------------------------------------------------------
alg22:

You use EQUATIONS to select current equation or LIBRARY to select a
built-in equation.  Press SOLVE.  You are presented with a menu of the
variables that appear in the equation.  Press one to select which
variable to solve for.  You will be prompted for values to use for the
other variables.

The prompt works by showing:

L?value

where "L" is the name of the variable being prompted for and "value"
is its current value.  You can simply press INPUT to re-use the value,
or enter an expression and press INPUT to use the calculated value.

------------------------------------------------------------
Algebraic:

This solver is similar to TVM5, except that it has been generalized to
handle any equation.

<name>		stores the value in the variable
STO <name>	stores the value in the variable
<name>		(2nd in a row), solves for the variable
RCL <name>	recalls a value from the variable

The solvers on the 17BII, 19B, 19BII, and -27S also have L(et) and
G(et) functions.

The solvers on the -17B, 17BII, -18C, 19B, 19BII, and -27S do
algebraic simplification

------------------------------------------------------------
equation

Similar to algebraic, except that a different interface is used.

------------------------------------------------------------
HP Solve

Similar to algebraic, except that a different interface is used.  Maybe
they'll finally stop fiddling with the user interface.

------------------------------------------------------------
RPL28:

Similar to algebraic, except that different keystrokes are used:

<value>		stores the value in the variable
<value> '<name>' STO	stores the value in the variable
Shift-<name>	solves for the variable
'<name>' RCL	recalls a value from the variable
'<name>' EVAL	recalls a value from the variable and evaluates it

------------------------------------------------------------
RPL48:

As with RPL28, it is similar to algebraic but different keystrokes are
used:

<value>		stores the value in the variable
<value> '<name>' STO	stores the value in the variable
<\ <name>	solves for the variable
/> <name>	recalls a value from the variable
'<name>' RCL	recalls a value from the variable
'<name>' EVAL	recalls a value from the variable and evaluates it

------------------------------------------------------------
RPN32:

Similar to alg22.  Press EQN to select the equation or FN= <letter> to
select an RPN program, then SOLVE <letter> to solve it for the
specified variable.  Prompting is the same as for alg22.  If you are
solving an RPN program, use RCL <letter> to indicate variables that
participate in solving.  You use R/S instead of INPUT to indicate that
you are done with the value.

------------------------------------------------------------
RPN42:

Your program starts with a global label, then a series of MVAR <name>
instructions, one for each variable that will appear in the menu.  It
then recalls each variable as needed to obtain the value.

You invoke the solver by pressing SOLVE <name>.  It then brings up a
menu similar to the algebraic solver.

<name>		stores the value in the variable
STO <name>	stores the value in the variable
<name>		(2nd in a row), solves for the variable
RCL <name>	recalls a value from the variable

------------------------------------------------------------
TVM4:

This solver does the "four value" TVM functions.  While there are five
named financial registers, you can only use the values in three of
them to solve for a fourth.  An extra bit is stored with each register
to record whether it has a value.  You thus have to store a zero to
actually mean a zero.

The valid combinations are:

input			solve for

n	i	PMT		FV and/or PV
n	i	FV		PV and/or PMT
n	i	PV		FV and/or PMT
i	PMT	PV		n
i	PMT	FV		n
i	PV	FV		n
n	PV	FV		i
n	PV	PMT		i
n	FV	PMT		i
i	n	PV		INT

Operations:

<name>		stores the value in the register
<name>		(2nd in a row), solves for the register

------------------------------------------------------------
TVM5:

This solver is the standard "five value" TVM function.  You can enter
any combination of four values and solve for the fifth.  The value in
the register that you are solving for is used as an initial guess, if
required.  Operation:

<name>		stores the value in the register
<name>		(2nd in a row), solves for the register
RCL <name>	recalls a value from the register

============================================================
From "HP Handhelds History -- Solvers Part 3"
by Wlodek Mier-Jedrzejowicz
in DATAFILE V22 N1 p17, January/February 2003

Type:
- TVM: Time Value of Money
- root: root finder

Vars:
- keys: labels on dedicated keys
- labels: labels in display
- list: variables listed in display

Year	Models		Type	Vars	Nature

1973	-80A		TVM	keys	Time Value of Money; n i PMT PV FV
-81A				keys below display.  Works in programs
-22A				on programmable models.
-27A
-92C
-37E
-38E
-38C
-12C

1974	programs for	various	various	Financial solvers and root finders were
-65A and later			available in HP Pacs and written by
users for programmable models.

1979	-34C		root		Root-finder function that looks for the
-15C				"zero" of an expression entered as a

1979	-14A ROMS	root		Math, PPC, Standard modules had root
finder programs.

1979	-14A ROMS	TVM	labels	Financial Decisions, Home Management,

1982	-75C Math ROM	root		This was a function for use by Basic
-75D Math ROM			programs.

1984	-71B Math ROM	root		Function to be used in Basic programs,
works recursively.

1984	-71B Solver	solver	labels	Chris Bunsen's original general root
program,			finder program usign the -71B Math
Circuit Analysis ROM		Pac.  Used in the Circuit Analysis PAC.

1984	-71B Finance ROM TVM		Finance program.

1986	-18C		solver	menu	First generation built-in solver to
-17B				analyze an expression, display its
-19B				variables, select and solve for an
-27S				unknown variable with an interface as
17BII				on TVM models.  "Expressions" were
19BII				algebraic equations or expressions and
could include tests and loops.  Allows
Let and Get functions.  This version
tries to find a direct solution by
rearranging the expression before
looking for a numerical root.

1987	-28C		solver	menu	Second generation general solver, works
-28S				with expressions and programs, so does
not look for a direct solution. Must
press Shift key before key of variable
to be solved for.

1988	-22S		sovler	list	Simplified equation solver, variable
names only one letter long.  No
rearranging, nor tests or loops.

1988	-32S		solver	list	Simplified general solver for RPN
programs.

1988	14B		TVM	keys	Algebraic model with TVM.
-10B
10BII

1988	-42S		solver	menu	General solver for RPN programs.

1989	-20S		root		Solver program, not a function.

1989	-21S		TVM		Finance program, not a function.

1990	48SX		solver	menu	-28C solver, extended by the Equation
48S				Library card.

1991	32SII		solver	list	-32S solver extended to work with
equations, too.

1991	95LX		solver	menu	The same solver as on the -18C,
100LX				rewritten to work on these DOS
200LX				palmtops.  Integrated to work with
700LX				Lotus 1-2-3 as a "back solver." Let
and Get are described in the manual.

1991	OmniBook 300,	solver	menu or	Same solver as on the palmtops above,
425, 430		list	integrated into a Windows environment.
Get and Let do not work.

1993	48GX		solver	menu or	48SX solver extended and with option
to prompt for the variables.

48G			list
48G+

1995	38G		solver	list	48GX solver transferred to these
38g+				teaching models.
39G
40G
40GS

1995	OmniGo 100, 120	TVM	keys	-12C emulator provides a TVM solver.

1999	49G		solver	list	48GX solver, menu option hidden at