HP HP-28S User Manual

Expressions as Functions. In chapter 4 you created the expression
RTOT and, using the Solver, assigned values to the variables and then
evaluated RTOT to calculate the desired result. In this case the
expression acted as a function which, given the input values,
produced a result.
Expressions as Implicit Equations. In
chapter 8 you used the
Solver to find the numerical zero of an expression-that is, the
numerical value of the independent variable for which the expression
has value O. In chapter 9 you used QUAD to find a symbolic zero-
that is, an expression which, substituted for the independent variable,
would give
the original expression the value O.
In both cases the expression f(x) acts like the equation f(x) = 0,
because the zero of the expression is the same as the root of the
equation.
Equations
Equations comprise two expressions related by an equals sign (=). In
mathematics there are two uses for the equals sign:
•
To indicate a proposition, such as u
x
2 = 4
U
or u
x
2 + y2 = 1.
u
Here
the equation holds only for some values of the variables .
•
To indicate an identity or definition, such as usin 2x = 2 sin x cos XU
or u
y
= 3x
2
+ 2x + 5." Here the equation holds for all values of
the variables.
On the HP-28S, equations are used for propositions only; to make a
definition
such as fly = 3x
2
+ 2x + 5," the expression
'3l>::·····2+2l>::+5' is stored in a variable named Y.
In "Time Value of Money" on page 103, both TVM and SPPV are
expressed
mathematically as equations. The TVM equation, which
holds only for certain values of its variables, is entered as an equation;
but SPPV, whose value is defined by the value of its variables, is
created as a variable.
162 16: Objects

HP HP-28S Specifications

General

Introduced	1988
Memory	32 KB
Number of Digits	12
Type	Scientific Calculator
Manufacturer	Hewlett-Packard (HP)
Display	LCD
Processor	Saturn
Programming	RPL

Summary

HP-28S Advanced Scientific Calculator Owner's Manual

Part 1: Fundamentals

Introduces basic operations, calculator features, and core concepts.

Getting Started

Covers initial setup, basic operations, and calculator overview.

Doing Arithmetic

Explains methods for performing calculations using stack and expressions.

Part 2: Summary of Calculator Features

Objects

Describes fundamental data types, symbolic operations, and programming elements.

The Command Line

Explains input methods, cursor control, and command entry.

The Stack

Reviews stack concepts and commands for manipulating objects.

Part 3: Programming

Program Structures

Covers conditional logic, loops, and error handling in programs.

Conditional Structures

Explains testing conditions and making decisions within programs.

Definite Loop Structures

Details structures for executing code a specific number of times.

Appendixes & Indexes

Appendix A: Assistance, Batteries, and Service

Provides troubleshooting, battery info, and service details.

Answers to Common Questions

Addresses frequent user queries and common calculator issues.

Appendix B: Notes for HP RPN Calculator Users

Highlights differences for users familiar with RPN calculators.

Appendix D: Menu Map

Lists commands by menu, with descriptions and page references.

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