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

Built-in macros


Needless to say, the Julia team has put macros to good use. To get help information about a macro, enter a ? in the REPL, and type @macroname after the help> prompt. Apart from the built-in macros we encountered in the examples in the previous chapters, here are some other very useful ones (refer to the code in Chapter 7\built_in_macros.jl).

Testing

The @assert macro actually exists in the standard library. The standard version also allows you to give your own error message, which is printed after ERROR: assertion failed.

The Test library contains some useful macros to compare the numbers:

using Test 
@test 1 == 3 

This returns the following:

Test Failed at REPL[5]:1
  Expression: 1 == 3
    Evaluated: 1 == 3
ERROR: There was an error during testing.

@test with the operator tests whether the two numbers are approximately equal. @test 1 ≈ 1.1 returns Test Failed because they are not equal within the machine tolerance. However, you can give the interval as the last argument within...