HP HP-28S User Manual

The clauses in the example represent simple numerical calculations,
but you can include any sequence of objects and commands. In effect,
a clause is like a subprogram within the program. If you write a sepa-
rate program that contains the clause and store this program in a
variable, you
can use the variable's name as the entire clause. In this
case a simple-looking
structure like
IF A THEN B ELSE C END
can represent a complicated decision process with two possible com-
plicated results,
depending on the contents of A, B, and C.
IF ... THEN ... ELSE ... END
Using the terminology just defined, the evaluation of this conditional
structure can be described as follows: The IF clause is evaluated and
returns a flag. If the flag is true, the THEN clause is evaluated; if the
flag is false, the ELSE clause is evaluated.
For
another example of this structure, see "FIB2 (Fibonacci Numbers,
Loop Version)" on page 248.
IFTE (If-Then-Else-End Function)
The first example in this chapter can be written in algebraic syntax by
using the function IFTE:
I IFTE(X;o'!0,SINOO/X, 1) I
This form is handy for symbolic calculations. If you execute the pro-
gram-structure version while X is undefined, this algebraic form is the
result. The arguments to IFTE must be representable in algebraic syn-
tax; to include RPN commands in the conditional, you must use the
program-structure form.
The IFTE function is used in "FIBl (Fibonacci Numbers, Recursive
Version)" on page 247.
226 26: Program Structures

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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