Richard Smith asks and answers: Is it Christmas Yet?

Depending on which day you decide to watch this recording, you may get a different answer from the one that Richard did as he answered his own question (“Is It Christmas Yet?”) in the first minute of his presentation. Of course, the true purpose of the talk was to show off a potential new system function for converting between a variety of time encodings. Not just the obvious ones like the 7-element ⎕TS format timestamp and the Dyalog Date Number, which is the number of days since the 31st of December 1899, but also a variety of Julian Dates, ⎕FRDCI style timestamps, UNIX time, Excel datetimes, Stata, R and SPSS dates and more – a total of more than 20 different time formats. Richard also shows how version 18.0 will allow you to determine the time in different time zones, and ends with formatting the current time in Helsinki – in Welsh.

Roberto and students from Liceo Scientifico GB Grassi Saronno

Inspired by Tetsuya Miyamoto, the inventor of the KenKen and other puzzles, Roberto Minervini avoids lecturing and prefers to present students with puzzles that they will be motivated to solve, learning new skills including mathematics and APL in the process. Pietro, Gabriele, Alessandro had their first exposure to APL in Roberto’s class at the at the Liceo Scientifico GB Grassi Saronno near Milan in Italy. Together with Roberto, they have created “MathMaze”, a platform for hosting real-time puzzle tournaments.

In this talk, they explain the unique scoring algorithm and the difficulty of creating puzzles that don’t make it clear whether you should solve them by thinking about them, by making drawings, or using the computer. A really good puzzle will requires a combination of techniques. As Alessandro explains, APL makes me think about the real mathematics behind a puzzle before I start writing the code.

Summary of this week’s videos:

• D08: Is it Christmas Yet? (Richard Smith)
• U11: Why Teach APL? The Art of Teaching Without Teaching (Roberto Minervini with Pietro Pio Palumbo, Gabriele Meroni and Alessandro Iaselli, Liceo Scientifico GB Grassi Saronno)

(Video releases will resume in January 2020)

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When Aaron Hsu was at Dyalog ’19 in Elsinore, he was preparing the defence of his PhD Thesis on A Data Parallel Compiler Hosted on the GPU. In his talk “Lessons for the Masses from the Trenches of Co-dfns” he looks back on some of the key lessons learned while working on the PhD and the Co-dfns compiler.

Aaron Hsu presents some of his insights from his work on the Co-dfns project

As usual, Aaron delivered a talk designed to make every one of us question the fundamental assumptions that we make about programming. Selected sound bites include:

Uncle Andy’s back with another fireside chat

To bring you back down to earth, (Uncle) Andy Shiers’ fifth Fireside Talk is about little things that Andy thinks are important to anyone managing or using a Dyalog APL installation that he suspects you have forgotten about, or may have missed when reading the documentation. Some of them are things that he overheard developers talking about and suspects are not documented at all! Most of them are things that he needed himself, or used to handle a support call. Serial numbers play an important role this year; the changes we have made so that we can support the use of unregistered versions of APL for testing and demonstration purposes make it important to understand the impact of serial numbers and how to manage them.

Join us again in week 9 to hear Richard Smith explain how to compute whether it will soon be Christmas and Roberto Minervini (and students) tell us about the Art of Teaching without Teaching.

Summary of this week’s videos:

• U03: Lessons for the Masses from the Trenches of Co-dfns (Aaron Hsu, Indiana University)
• D13: Uncle Andy’s Fireside Chat v5 (Andy Shiers)

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Week 7 features talks by two recent additions to the Dyalog team. Richard Park joined Dyalog a year ago, and his primary focus is the production of new teaching materials. Nathan Rogers is the newest member of our US consulting team and is based in Denver, Colorado.

Jupyter notebooks have recently become a very popular mechanism for publishing scientific and technical content. In addition to nicely formatted text and graphics, notebooks can contain executable expressions in a growing collection of programming languages – including Dyalog APL. In his talk at Dyalog ’19, Richard shows that it has become really easy to get started with notebooks containing executable APL code. Thanks to recent work that he has done, you can even get started without installing anything on your own machine!

Richard Park shows a new way to access Jupyter documents

Nathan Rogers presents APL2XL from the other side of the ocean

Excel workbooks are nothing new; the first version of Microsoft Excel appeared in 1987, only 4 years after the release of Dyalog version 1.0. For decades, users have used OLE Automation to interact with Excel and create workbooks. However, this is not a suitable technology for use on servers (even Windows-based servers). Nathan could not attend Dyalog ’19 in person due to a theatre production in Denver where he was a member of a team dancing tango, so he had to present his APL2XL project via a remote connection. The goal of this open source project is to create Excel workbooks (.xlsx files) under Windows, Linux and macOS, without any external requirements other than Microsoft .NET compression libraries.

Summary of this week’s videos:

• D16: Creating your First Dyalog Jupyter Notebook (Richard Park)
• D12: Exporting Simple Microsoft Excel Tables from APL (Nathan Rogers)

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