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

functions


Functions can be nested, as demonstrated in the following example:

function a(x) 
    z = x * 2 
    function b(z) 
        z += 1 
    end 
    b(z) 
end 
 
d = 5 
a(d) #=> 11

A function can also be recursive, that is, it can call itself. To show some examples, we need to be able to test a condition in code. The simplest way to do this in Julia is to use the ternary operator ? of the form expr ? b : c (ternary because it takes three arguments). Julia also has a normal ifconstruct.(Refer to the Conditional evaluation section ofChapter 4, Control Flow.expr is a condition and, if it is true, then b is evaluated and the value is returned, else c is evaluated. This is used in the following recursive definition to calculate the sum of all the integers up to and including a certain number:

sum(n) =  n > 1 ? sum(n-1) + n : n 

The recursion ends because there is a base case: when n is 1, this value is returned. Here is the famous function to calculate the nth Fibonacci number that...