Dyalog ’14

Use a gun in a crime and, thanks to recent biochemical advances, you'll likely leave enough DNA to be detected. However, often the gun has also been handled by others and consequently the analysis of DNA mixtures has become increasingly important. The market for good DNA mixture software therefore has led me to recent and rapid progress in my long-delayed venture to convert my forensic DNA interpretation work into the modern world of Dyalog. Many people enjoy the scientific aspects of the story and I enjoy relating how, in my view, this project exemplifies the thesis that APL is a tool of thought. I credit APL with leading me to elegant and, therefore, very fast and flexible solutions to a problem for which the competing solutions are lumbered by complicated statistical and Monte Carlo methods.

Elegance and simplicity lead to several concrete benefits. The first is conceptual development. I made notes in APL as solutions to various aspects of the problem occurred to me last year. These brief APL notes ensured that the ideas really made sense, that they worked together and that I would not forget them. The brevity also revealed a simple but important point that others had overlooked: nesting the computation loops in the right order saves orders of magnitude in computation time. For another, execution speed makes it much easier to see the forest in many ways – testing, developing, designing. Competing programs take hours to find a partial answer, then having worked that hard succumb to a natural tendency to call it a day. The APL "DNA-VIEW Mixture Solution" program does the same in seconds which makes it much easier to think through to the fact that there's a lot more work to do before the result is logically defensible. At the end of 2013 I implemented the Mixture Solution and tested it on examples including a set of 5 proficiency exercises created at the National Institute of Standards and Technology. More than one hundred entrants, including the leading competition, had contributed analyses. One of the competitors (supported by years and millions of dollars of government grants) got four problems right and came close on the fifth, viewing it as a three person mixture although in fact it was four. Mixture Solution alone correctly analysed all five – as a bonus it correctly diagnosed one suspect as a mixed race person. We APLers try to be modest but it's not always easy. Sometimes there's just not much to be modest about!

Pension microsimulation model ELSI has been built in the Finnish Centre for Pensions using Dyalog. ELSI models the statutory pension system of Finland. It is used for reform analysis and long-term projections. In a typical simulation run, we have 500,000 individuals and 70 simulation years.

Acre, the APL Code Repository, is a code management system that covers everything a team of APL developers might need – once you've seen it in action you'll wonder how you managed to survive without it!

From APLers for APLers, Acre was written by Phil on behalf of the Carlisle Group (the company behind FlipDB, a relational database fully written in Dyalog).

Phil and Kai briefly cover the basic concepts behind Acre then demonstrate in a development session how to convert an application into one or more Acre projects, check out the code, make changes, perform backups, watch what others are doing and check in changes after solving conflicts along the way.

Both Acre and Acre Server, a RDBMS that acts as the repository, will be available free-of-charge from the APL Wiki after this presentation.

The professional programmer strives for maintainable code, well aware that an unmaintained codebase gradually transforms from a well-tended garden to a dark haunted forest that requires animal sacrifice if left to its own devices. Far too many systems have "that" piece of code – the unmaintained marsh, the mess that causes nausea and elevated blood pressure. Some people swear developers have lost parts of their souls in there and you can hear screaming if you work late enough for long enough...

This talk lays bare some of the underlying mechanics of maintainability, presenting a definition of maintainability based on human cognition and sharing a language that might help when talking and reasoning about maintainability. Ultimately we are all responsible for maintaining our codebase; software entropy is real and we pay in blood, sweat and tears if we choose to ignore it.

Statistical functions are numerous, but they can be categorised into groups. We can reduce the total number of statistical functions by creating a few functions and designing various operators to modify them. For instance, most statistical distributions come in three general forms; the density or probability mass function, the cumulative distribution function and the inverse or critical value function. Limited-Domain Operators are designed to work with specific classes of functions. For example, probability is a dyadic operator whose left operand must be a density or probability mass function and whose right operand must be a relational function. Other limited-domain operators include criticalValue, randomVariable, theoretical, goodnessOfFit, confidenceInterval and hypothesis.

At SimCorp we rely heavily on static analysis and type checking to maintain our large APL code base. We have recently rewritten our analysis tool from scratch as the old version had some flaws and relied on ad-hoc parsing. The new tool solves the APL parsing problem using a two-step parsing algorithm with a crucial kind inference algorithm in between; this allows the resulting parser to use standard LALR(1) parsing generated from a BNF by a standard Yacc. Furthermore, the BNF grammar is conflict-free, so no precedence or associativity declarations are needed as there are no shift-reduce or reduce-reduce conflicts, making maintenance of the grammar easier.

The Co-dfns project aims to deliver a high performance compiler for a parallel extension of the dfns language. This report will provide an update on new features and platforms for the compiler, including GPU execution, massively parallel distributed computing and significant sequential performance improvements. It will also cover new frameworks to make APL development safer, faster and easier.

Fine Analytics have taken advantage of the WPF capabilities and Syncfusion controls available with Dyalog 14.0 to build a generic asset allocation platform with special focus on the professional investor. A specially designed .NET class facilitates the separation of the administrative and analytical sections of the application and a flexible calculation engine that allows a user to define type/structure/order is an integral part of the platform. All assumptions can be controlled from the professional-looking user interface; the user interface can also be used to change/import/construct/delete/add/copy/export a portfolio as well as add new assets in asset groups.

Programming keywords: docking manager, treeview, gridcontrol, sfchart, tabcontrol, menu, toolbar, statusbar, groupbar, tileview, databinding, datatemplate, events, triggers, commands, xaml, combobox, listbox, doubleedit, maskededit, fonts, updown, Grid, stackpanel, rangeslider, save, open, explorer and more...

Vallourec is a world leader in premium tubular solutions primarily serving energy markets (oil and gas, power generation). Its expertise also extends to the industry sector (including mechanical engineering, automotive and construction). With more than 24,000 employees, sales of €5.6 billion in 2013, integrated manufacturing facilities in more than 20 countries and cutting-edge R&D, Vallourec provides customers with innovative global solutions that respond to the energy challenges of the 21st century.

Dyalog is used to develop planning tools for the tube production in the German and Chinese plants. This presentation will give an overview of the functionalities of the major applications written in Dyalog. These tools are small in sense of users, but very important for the planning department. The rules inside the system cover the experience in tube production for many years. Java is used for new applications at Vallourec Germany but this presentation will show a few examples of why APL can still compete with "modern" programming languages.

About the speaker: Stephan Poßberg is Project and Process Engineer at Vallourec Deutschland GmbH and responsible for APL development (among other things). He holds a PhD in Mechanical Engineering from the University of Paderborn.

The sixth annual International APL Programming Contest took place earlier this year. Brian introduces the contest and winners and Walt presents them with their certificates in the Prize Ceremony.

Emil Bremer Orloff is the grand prize winner of the sixth annual International APL Programming Contest. Following the prize ceremony, Emil will describe his experiences of Dyalog and tell us how he managed to master enough of it to win the competition.

Iryna Pashenkovska is the winner of the non-student category in the sixth annual International APL Programming Contest. Following the prize ceremony, Iryna will describe her experiences of Dyalog and tell us how she managed to master enough of it to win the competition.

We have been working with a new Academy free school, which is located over two main sites and has an external catering hall. The school is for pupils aged from four to eleven years and provides before-school and after-school clubs and mini-bus services.

We designed our school "LASER" system as a complete communication and information system between parents and school staff; recently we have expanded the system to use NFC (near field communication) to provide teachers and staff with up-to-date, relevant information. Each pupil in the school is issued with an NFC wristband and tags for their bags and key items of uniform. Staff use NFC-enabled mobile phones or NFC readers connected to PCs to log a pupil at key points, for example, on and off a bus or at the dining hall. The NFC tags let the lunch staff know what food order the parents have requested each day and can give a full itinerary of clubs and school activities. Alerts of allergies or other critical medical information is displayed when a tag is scanned.