Book Image

Julia 1.0 Programming. - Second Edition

By : Ivo Balbaert
Book Image

Julia 1.0 Programming. - Second Edition

By: Ivo Balbaert

Overview of this book

The release of Julia 1.0 is now ready to change the technical world by combining the high productivity and ease of use of Python and R with the lightning-fast speed of C++. Julia 1.0 programming gives you a head start in tackling your numerical and data problems. You will begin by learning how to set up a running Julia platform, before exploring its various built-in types. With the help of practical examples, this book walks you through two important collection types: arrays and matrices. In addition to this, you will be taken through how type conversions and promotions work. In the course of the book, you will be introduced to the homo-iconicity and metaprogramming concepts in Julia. You will understand how Julia provides different ways to interact with an operating system, as well as other languages, and then you'll discover what macros are. Once you have grasped the basics, you’ll study what makes Julia suitable for numerical and scientific computing, and learn about the features provided by Julia. By the end of this book, you will also have learned how to run external programs. This book covers all you need to know about Julia in order to leverage its high speed and efficiency for your applications.
Table of Contents (17 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

Defining functions


A function is an object that gets a number of arguments (the argument list, arglist) as the input, then does something with these values in the function body, and returns none, one, or more value(s). Multiple arguments are separated by commas (,) in an arglist(in fact, they form a tuple, as do the return values; refer to theTuples section ofChapter 5, Collection Types). The arguments are also optionally typed, and the type(s) can be user-defined. The general syntax is as follows:

function fname(arglist) 
    # function body... 
    return value(s) 
end

A function's argument list can also be empty; in this case, it is written as fname().

The following is a simple example:

# code in functions101.jl 
function mult(x, y) 
       println("x is $x and y is $y") 
       return x * y 
end 

Function names such as mult are, by convention, in lower-case. They can contain Unicode characters, which are useful in mathematical notations. The return keyword in the last line is optional; we...