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GNU Octave Beginner's Guide

You're reading from   GNU Octave Beginner's Guide Become a proficient Octave user by learning this high-level scientific numerical tool from the ground up

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Product type Paperback
Published in Jun 2011
Publisher Packt
ISBN-13 9781849513326
Length 280 pages
Edition 1st Edition
Languages
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Author (1):
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Jesper Schmidt Hansen Jesper Schmidt Hansen
Author Profile Icon Jesper Schmidt Hansen
Jesper Schmidt Hansen
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Table of Contents (15) Chapters Close

GNU Octave
Credits
About the Author
About the Reviewers
1. www.PacktPub.com
2. Preface
1. Introducing GNU Octave FREE CHAPTER 2. Interacting with Octave: Variables and Operators 3. Working with Octave: Functions and Plotting 4. Rationalizing: Octave Scripts 5. Extensions: Write Your Own Octave Functions 6. Making Your Own Package: A Poisson Equation Solver 7. More Examples: Data Analysis 8. Need for Speed: Optimization and Dynamically Linked Functions Pop quiz - Answers

Comparison operators and precedence rules


In the previous section, we discussed the basic arithmetic operations. In this section, we will learn how to compare different variables. Octave (like many other programming languages) uses very intuitive operator characters for this. They are:

x==y

Evaluates to true if x equals y

x>y

Evaluates to true if x is larger than y

x<y

Evaluates to true if x is smaller than y

x>=y

Evaluates to true if x is greater than or equal to y

x<=y

Evaluates to true if x is smaller than or equal to y

x!=y

Evaluates to true if x is not equal to y

For Octave's comparison operators, true is equivalent to a non-zero value and false is equivalent to 0. Let us see a few examples—recall the matrix A from Command 93:

octave:108> A(2,1) == 1
ans = 1
octave:109>A(2,1) == 2
ans = 0
octave:110> A(2,1) > 0
ans = 1
octave:111> A(2,1) != 4
ans = 1

Instead of using != for "not equal to", you can use ~=.

You may be familiar...

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