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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

Writing and applying user-supplied functions


In Chapter 3, we saw how to "build" mathematical functions directly via the Octave command prompt. Here we will do the same thing, but we will do it properly this time and use Octave functions.

Consider the following vector valued function which we will call the Sel'kov function (an explanation follows later):

(5.1)

b is some positive real number that we can vary as we like. We can write Equation (5.1) in a slightly different way by letting (x,y)=(x1,x2)=x:

(5.2)

When we write an Octave function for Equation (5.2), we can specify the value of b in at least three different ways:

  1. 1. We can simply set the value of b inside the function (inside the function scope)

  2. 2. We can let b be input to the function

  3. 3. We can let b be a global variable such that its value is accessible from both the workspace and inside the function scope

The first option is a bad choice, because we then have to change the value of b inside inside the function every time we need to change...

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