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

Dates and times


To get the basic time information, you can use the time() function that returns, for example, 1.408719961424e9, which is the number of seconds since a predefined date called the epoch (normally, the 1st of January 1970 on a Unix system). This is useful for measuring the time interval between two events, for example, to benchmark how long a long calculation takes:

start_time = time() 
# long computation 
time_elapsed = time() - start_time 
println("Time elapsed: $time_elapsed") 

Use the Dates module that is built in into the standard library, with Date for days and DateTime for times down to milliseconds, to implement this. Additional time zone functionality can be added through the Timezones.jl package.

The Date and DateTime functions can be constructed as follows, or with simpler versions with less information:

  • d = Date(2014,9,1) returns 2014-09-01
  • dt = DateTime(2014,9,1,12,30,59,1) returns 2014-09-01T12:30:59.001

These objects can be compared and subtracted to get the duration...