HP HP-42S User Manual

When we leave the program mode and go to the Solver menu again we select FX program and what
we are going to see is
A B C X
Now just enter the values of A, B, C and a start value for X and we are done.
Some interesting things to say are:
1. We can't find complex solutions.
2. In this particular case we are not limited to the case a ≠ 0.
3. For polynomial equations it is more generally useful to write a more complex equation like
ax
4
+ bx
3
+ cx
2
+ dx + e = 0. We can set the coefficients of the higher order terms to zero if
we want to solve a lower order polynomial.
4. In any equation we are not limited to find one specific variable, say X, of course we can find
any missing variable.
5. We don't need to use the solver only for “complex” hard to find solution equations. We can
use the solver just to automate some easy calculations.
6. We ordinarily do not need to enter a starting guess for the variable we are solving for — just
press that menu button without keying a value first, and the Solver will solve for it.
Example: Consider the ideal gas equation PV=nRT where R is 8.3144472 J/mol . K. We can write a
program like
01 LBL “GAS”
02 MVAR “P”
03 MVAR “V”
04 MVAR “N”
05 MVAR “T”
06 RCL “P”
07 RCL “V”
08 ×
09 RCL “N”
10 RCL “T”
11 8.3144472
12 ×
13 ×
14
15 RTN
16 END
So we will have in the solver menu P V N and T. If we want to know how many moles of an ideal gas
is inside a container of 1L at a 1000Pa pressure and at 300K all we have to do is10000 P 0.001 V
300 T and we give a try for N, for example 1 N and then pressing N again we have 0.0040
moles.
8 Numeric Integration
Suppose we want to solve numerically a integral of the form
∫
b
a
dxxf )(
We write the function in the same way we did in the solver case.

HP HP-42S Specifications

General

Model	HP-42S
Manufacturer	Hewlett-Packard
Release Year	1988
Display	LCD
Processor	Saturn
Programming	RPN
Special Features	Matrix operations, complex numbers
Category	Programmable Scientific Calculator
Dimensions	148 x 80 x 15 mm

Summary

2 Basic Operations

2.1 RPN Explanation

Explains Reverse Polish Notation (RPN) and its usage on the HP-42S calculator.

2.4 Training RPN with HP-42S

2.5 Understanding Menus

2.6 DISP Menu Functions

2.7 MODES Menu

Covers angle modes (DEG, RAD, GRAD) and coordinate systems (REC, POLAR).

2.8 The Stack

Explains the calculator's stack registers (X, Y, Z, T) and their behavior.

2.9 Key Usage Guide

Details the function of various keys like 1/x, LOG, LN, XEQ, STO, RCL, SIN, COS.

3 Memory Management

3.1 The CATALOG Menu

3.3 The CUSTOM Menu

5 Complex Numbers

5.1 Rectangular Coordinates

How to input and manipulate complex numbers in rectangular form.

5.2 Polar Coordinates

6 Programming

6.1 Basic Programming Concepts

Introduces fundamental programming concepts and syntax.

6.2 Managing Multiple Programs

6.3 Conditional Execution (X?0, X?Y)

Explains conditional execution (IF statements) in programming.

6.4 Real Program Examples

Practical examples of programs, including a prime checker.

7 Using the Solver

Solver Feature Guide

Guide to using the equation solver feature for numerical solutions.

8 Numeric Integration

Numeric Integration Guide

How to perform numerical integration of functions using the calculator.

9 Statistics

9.1 The CFIT Sub-menu

10 Matrices

Matrix Operations Overview

Covers matrix operations, creation, inversion, and determinants.

12 Flags

Calculator Flags Explained

14 Comprehensive Command List

HP-42S Command Reference

An alphabetical reference of all HP-42S functions and commands.