Announcing the Beta Programme for Dyalog APL Version 18.2
I am very pleased to be able to announce the start of the Beta testing of the next release of Dyalog APL! As explained in June, we decided to delay the release of version 18.1 in order to take a closer look at some of the optimisations that had been implemented in 18.0 (and were […]
News and Recommendations Regarding Dyalog Versions 17.1, 18.0 and 18.1
Background Dyalog version 18.0 contained the largest number of optimised algorithms in the history of Dyalog APL. Unfortunately, since its release, we have found that our process for review and testing of optimisations was insufficient to cope with the quantity and nature of the optimisations. Many of the new algorithms had edge cases that escaped […]
Towards Improvements to Stencil
Background The stencil operator ⌺ was introduced in Dyalog version 16.0 in 2017. Recently we received some feedback (OK, complaints) that (a) stencil does padding which is unwanted sometimes and needs to be removed from the result and (b) stencil is too slow when it is not supported by special code. First, stencil in cases […]
Tolerated Comparison, Part 2
This post might be more difficult than our usual fare. You won’t find any interesting APL coding insights here—instead we’ll be focused on the tricky topic of floating-point error analysis. If that’s not your thing, feel free to skip this one! Although if you plan to use tolerated comparison in a real application, you really […]
Dyalog '18 Videos, Week 3
The four presentations from Dyalog’18 that we are releasing this week address both the visible (user interface) and invisible (performance) parts of application design. Starting with performance: This quote was at the heart of the talk by our invited keynote speaker Martin Thompson. In order to write software which performs well, you need to have […]
Tolerated Comparison, Part 1
Warning: The formula for “tolerated” comparison in this post is not correct for actual floating-point numbers. Do not use it! The follow-up post discusses how to compute the required value precisely in the presence of floating-point error. Tolerant comparison is an important feature in making APL usable in the real world. But it’s also a […]
Expanding Bits in Shrinking Time
The chart above compares the performance of ∘.∧ in Dyalog versions 16.0 and 17.0. The improvement is a factor of 3-4 across the whole range (except at multiple-of-8 lengths, where 16.0 spikes up). That’s not easy to get, especially for a function like ∘.∧ which was already the target of a fair amount of special […]
Stackless Traversal
Enlist (∊) is twice as fast in Dyalog 16.0 as it was in Dyalog 15.0. Pretty much across the board: ∊⍳100 is not going to be any faster, but whenever the argument is a nested array and the simple arrays it contains are reasonably small, there are huge performance improvements. How did we achieve the […]
