Author: merovingienne

• Sinhala Palindromes

  Palindromes are words, phrases or sequences that read the same forwards and backwards. They are interesting due to their symmetry. There is no singular term for palindromes in Sinhalese. But in the study of Sinhala poetry, there is a poetic device employing repetition of sounds known as Prathilōma Yamaka (/prəθɪlɔːmə jʌməkə/; Sinhala: ප්‍රතිලෝම යමක)^[1], which loosely translates to “reversed repetition”.

  This post first lists some palindromes in Sinhala. Next, I share some thoughts on the difficulty in creating Sinhala palindromes compared to English.

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  List of Sinhala Palindromes

  Palindrome	Meaning
  වටාපිටාව	Surrounding
  මල කෝලම	Nonsense
  රතු කතුර රතු වතුර රතු යතුර රතු පතුර	Red scissor Red water Red key Red splinter/chip
  ගමන්මග	Path
  වඩු මඩුව	Carpenter’s shed/workshop
  රන මොනර	A type of peacocks. (literally war peacock. Used in literary contexts).
  මහළු හම	Old/elderly skin
  මිහිඳු හිමි	Mihindu Thero
  තව වත	Asceticism Ascetic’s story Ascetic’s face Ascetic’s cloth
  තාත්තා	Father
  තාත්තා ගේ තාත්තා	Father’s father
  මාමා	Uncle
  මාමා ගේ මාමා	Uncle’s uncle
  සස	Rabbit
  සමාස	Compound terms (linguistic)
  සවස	Evening
  නයන	Eyes
  නගන	Hordeolum/Stye
  නග්න	Naked/Nude
  වනසනව	Destroying
  විකට කවි	Funny poems
  දිනිදි නිදි	Dinidi is asleep
  නාගොඩ ගොනා	Bull of Nagoda

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  Palindromes in Sinhala and English Languages

  Before we compare how the formation of palindromes differ between Sinhala and English, we first need to know two categories of palindromes:

  1. Written palindromes – words, phrases or sequences that are spelled the same way forwards and backwards.
  2. Phonetic palindromes – words or phrases that sound the same when spoken/played forwards or backwards. The spelling can differ between the forward and backward sequences, but the phonetic pronunciation is symmetrical.

  In written palindromes, visual symmetry of the sequence of characters is the key characteristic – they look the same in written form when reversed. The meaning often changes when such a palindrome is read backward. For phonetic palindromes, auditory symmetry is the most crucial aspect. These are less common than written palindromes as spoken language has more nuances and variations. Note that these two categories are not mutually exclusive: a written palindrome may very well be phonetically reversible!

  Sinhala, with its larger alphabet, seems like it would offer more palindromes, but it’s actually more challenging. This is because Sinhala uses ‘diacritics’ – marks added to letters to alter their sound or to represent a different sound altogether. English treats vowels as individual letters, which allows for more variety when flipping words to create palindromes. So, when you’re trying to form a palindrome in Sinhala, each letter with its diacritics must match exactly in reverse order, limiting the options you have for creating words. As a result, Sinhala palindromes are naturally phonetic as well as written the same way backward. These dual constraints make it easier to find palindromes in English than in phonetically restrictive Sinhala.

  English also has phonetic palindromes, which may or may not be spelled the same in reverse. The words “babe”^[2] and “dead”^[3] each sound similar when played in reverse but are clearly not spelled the same way backwards. On the other hand, “noon” and “deed” satisfy both the phonetic and spelling requirements.

  As you may have no doubt noticed, phonetic reversibility is a stronger condition than spelling reversibility. Thus, phonetic palindromes are rarer than mere written ones. Sequences with both properties are of course even harder to find.

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  References

  1. ඡන්දෝලංකාරා (Chandolankārā) – Prof. Bihesh Indika Sampath. Page 62. (PDF) ඡන්දෝලංකාරා (researchgate.net).
  2. On the Distinction Between “Phonetic” Palindromes and “Phonetically” Reversible Words (butler.edu)
  3. Phonetic Palindromes (butler.edu)

  October 31, 2023

  Sinhala

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• Falsy vs. Nullish Values in JavaScript

  This is a quick summary on Falsy and Nullish values in JavaScript. JavaScript has 8 falsy values, and 2 nullish values. The two nullish values are also falsy, but the rest of the falsy values are not nullish.

  Falsy Values

  A falsy value is something that is considered as false when used in a boolean context. JavaScript uses Type Coercion to convert non-boolean values in boolean contexts (such as a conditional, or a loop) into boolean form. There are 8 falsy values:

  Value	Description
  false	The keyword false
  0	Number 0
  -0	Negative number 0
  0n	0 in BigInt
  ‘’, “”	Empty string
  null	Primitive null – no value
  undefined	Primitive undefined
  NaN	Not a Number

  Nullish Values

  The two primitives null and undefined are known as nullish. Put simply, it means that they don’t have any value. They get converted to false via Type Coercion in a boolean context.

  

  By above definitions, we see that nullish values are also falsy.

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  0 vs null vs undefined

  Zero is fundamentally a numerical value, and thus is used to denote that a countable thing has none of its kind. As a numeric value, zero can be used with arithmetic operations.

  null is more generic than zero: it represents the absence of a value in any context. Note that null is an explicit value that needs to be intentionally set by a developer. Zero indicates a numerical value, whereas null says the property or variable being accessed exists, but it semantically has no value.

  undefined represents that a property or variable has not yet been assigned a value. This is also the default result when you try to access a property that does not exist.

  August 16, 2020

  JavaScript

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• The Curious Case of Division By 7

  It was a Monday. I was 14, and my math tuition class was in 2 hours. I was hurriedly going through the homework to be done. Yes, we’re all major procrastinators. My tutor had given 12 questions on division by integers. It was always 12 questions, because he could divide that number in many ways. This was useful in formatting the page layout of the questions; 2, 3, or even 4 columns per row.

  It was basic arithmetic, and there were two or three questions with 7 as the denominator. I don’t remember exactly what the numbers were, so let’s say they were 1/7, 2/7, and 5/7. Then there were other fractions with 3, 11, 5 and so on. While working out the decimal representations of these numbers, I realized something – the decimal part of fractions with 7 as the denominator had the same set of numbers, recurring every 6 digits.

  

  As you can see above, the numbers 1, 2, 4, 5, 7, and 8 repeat in the decimal part of these rational numbers. Interestingly, they repeat in a manner that shows a cyclic rotation; 142857 is repeated such that n/7 starts from the n^th largest number in the sequence 1, 4, 2, 8, 5, and 7, rolling over to the beginning when it reaches the end of the sequence.

  

  This means we can figure out the decimals of a number divided by seven, just by remembering the number 142857. Don’t ask me who would remember a random number like that. Some of us just do.

  For example, let’s take 213/7. Looking at the numerator, one could figure out that 210 is the nearest number divisible by 7. (21 = 3 x 7. Multiplication tables, anyone?). That means the decimal representation is 30… something, as the remainder is 3. For the decimal part, we have 30 + 3/7, where 3/7 is 0.428571… by the above pattern. So the answer for 213/7 = 30.428571…

  Pretty neat, as long as you remember 142857.

  That’s not all. Many rational numbers have recurring patterns in their decimal part. For example, any number divided by 9 gives the same number. So 4/9 = 0.444444… and 7/9 = 0.77777….

  Similarly, division by 11 results in multiplying the numerator by 9, and representing it to two decimal points, which then repeats itself. Thus,
  5/11 = 0.45 45 45… where 45 = 5 x 9
  3/11 = 0.27 27 27 … where 27 = 3 x 9 .

  Naturally, I was curious whether other numbers showed the same behaviour as 7. So I checked the decimal part of different rational numbers, intuitively checking with prime numbers as the denominator, since 7 is prime. I didn’t make much progress there, but I remember realizing 17 had such a cyclic rotation in its fractions. I just couldn’t figure out an easy way to derive the starting point of the repetend. Not that it would have been very useful anyway – the length of the repetend of 1/p is either p-1, or a factor of p-1 – not that easy to remember. I’ve only tried a max of 16 digits to remember in order so far. You can probably guess what for.

  Looking back now, I had accidentally discovered Cyclic Numbers. It was fun to play around with numbers back then, and we had enough free time to do stuff like that. Some of the best days, those were. And not just because of arithmetics ?

  If you’re interested in learning more about Repeating Decimals and Cyclic Numbers, take a look at the following Wikipedia articles. Have fun!

  • Repeating Decimals
  • Cyclic Numbers

  November 19, 2019

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• GSoC 2017 – Operation Theater Module Workflow Enhancements

  This post originally appeared in OpenMRS Talk as my final presentation.

  Operation Theater Module Workflow Enhancements

  Mentors: Akshika Wijesundara & Harsha Kumara

  Code contribution Summary: GitHub

  There’s a certain pleasure in seeing people make use of your work. That’s one of the main driving forces behind the open source philosophy. It’s deeply satisfying to know that your lines of code makes someone’s life easier, even if by just a little bit.
  But what about not just making lives easier, but helping to save entire lives? That’s some next level thing. Enter OpenMRS.
  This summer I had the opportunity to contribute with code to save lives, and this is my final note about the experience.

  (more…)

  August 28, 2017

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• GSoC 2017 With OpenMRS – Operation Theater Module Workflow Enhancements

  It’s a little hard to think 12 weeks have passed already. But as they say, all good things must come to an end. So goes Google Summer of Code 2017 with OpenMRS.

  This summer, I worked on the Operation Theater module to bring it up to speed with 2017. The project had 2 main targets.

  1. Migrate the module to work with the current OpenMRS platform.
  2. Add workflow enhancements pertaining to pre, post and in-theater stages.

  To remind what the operation theater module does, it basically helps us to schedule surgeries in the operation theaters within a hospital. We can add operation theater locations, save available procedures, schedule surgeries for patients and have a scheduling engine come up with the best schedule for current surgeries.

  We can also add a team of surgeons and other people who will be taking part in the surgery. But after making the module, it was somehow left behind and wasn’t updated along with the core of OpenMRS & other modules. It just went beep for 3 years.

  So my first task was to get it up and running. For this I had to first check what had changed between those 3 years and update the module codebase. I learned much about how the concept of time is handled in the programming world. I learned about Optaplanner, and constraint satisfaction problems in general (shout out to Charith sir for the Intelligent Systems lectures!). And bloody hell, I replaced an entire time library with two other libraries.

  Along with that, there were database changes. OpenMRS had migrated from Hibernate 3.x to 4.x, so the Operation theater module needed some changes on that front. There I learned a bit of Hibernate, the ORM (Object-relational mapping. It’s a database thing). So the first month was spent on updating the module codebase and dependencies.

  And we revved up the module.

  

  After adding an operation theater location from settings, we can access the scheduling page and start scheduling. But wait, you need to add some procedures first. Otherwise, what surgery are you going to schedule?

  

  

  

  And we’re good. So, first task, done!

  Next, we started doing workflow enhancements. The main focus here was on the collection of data throughout the surgery. Before starting a surgery, it’s important to know the history of the patient. What procedures have they done before? Are there any drugs we need to give before the surgery? Is the guy even fit to go into surgery? Curiosity to save a life. Or two, counting the surgeon’s.

  I initially planned to collect data as notes – free text. But the community suggested that we do it with concepts and observations, the preferred method of collecting data into OpenMRS. This way, we can use the collected data to generate reports and perform analytics. You can probably guess how hard that would be with free text.

  I was halfway through doing it with free text when I got the suggestion. After that, I rewrote the code with appropriate concepts. So now, we’re adhering to standards and working neater overall.

  We record past surgery data, allergies, physical condition and drug prescriptions during the pre-theater data collection.

  

  

  

  We do the same for in-theater and post-theater data. As for in-theater data, we decided to capture it in the post-operative form as it’s not practical to enter the data during the surgery.

  And that’s target number two, down. We’re all good with the primary tasks 😀

  After that, I started documenting the code and the module. I’ve written some tests to cover the code and tried to clean it up.

  I’ve learned a lot in these past few months, specially how a real project handles collection of data in a flexible manner. This is especially useful for some of my personal projects as well.

  As next steps, I’d much rather fully rewrite the scheduling engine myself. Then I know the module inside out from its core, and can help other people to get involved in maintaining it. Another possible extension is generating reports from the data we collect. It’s just a matter of presenting the data in suitable formats.

  And that’s it for this time, people. We’ll wrap it up after the final evaluations in one more post.

  Until then, take care.

  August 22, 2017

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• GSoC 2017 – Operation Theater Module Workflow Enhancements

  This is the official blog for my Google Summer of Code 2017 project. I am going to be working for OpenMRS, an open source project that supports healthcare delivery around the world. It feels great to have been awarded this opportunity, thank you @Team OpenMRS! ?

  My project is to work on the Operation theater module, which has been made as part of GSoC 2014. It’s used to schedule surgeries and other operation theater activities in multiple theaters. The module was written for an older OpenMRS version, so my first task is to migrate it to the latest platform.

  (more…)

  May 21, 2017

  GSoC, OpenMRS

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• Biometric Identification with Keystroke Dynamics Using Java

  So this started off as an assignment but turned out to be quite fun by the end of it. We were asked to make a biometric identification system with Java using any biometric identifier. There was one restriction – no libraries were allowed. Out went OpenCV and pretty much anything that could be made to work reliably within the time-frame of a week.

  My first thought was to make a voice identifier – a system in which the distinct features of someone’s voice would be saved in order to identify them uniquely. But that turned out to be far more time-consuming than I thought and involved libraries which I could not adopt. There wasn’t much time to write them myself. So after 3 days of struggling, I switched to keystroke dynamics.

  What’s keystroke dynamics? It’s the official term for the unique way you type on a keyboard. Turns out that each of us use keyboards differently – with more than just a change in overall speed. We spend different amounts of time pressing each key and moving onto another, have our own favourites among the Shift keys and show unique patterns while moving from one key to another. And these little things add up to a relatively strong set of features that can uniquely identify someone.

  (more…)

  March 12, 2017

  Java

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• KidsIgnite – How I became the father of 20

  When Achala asked me to help him out with an electronics class for kids, I didn’t know what I was signing up for. It was in June 2016 – I was free procrastinating uni work, and this seemed like a good distraction. I mean, it was kids. Plus electronics. Kids are fun(!). How hard could it get?

  But no, oh no. Joining Igniter Space (formerly KidsIgnite) changed quite a few of things in my life, including some life goals. I’ve seen most, if not all, kinds of kids from angels to brats. I’ve had the chance to teach basic calculus & programming, and clean up snot. I’ve cuddled the cutest of kids, and had my hair pulled off with a plier.

  Okay, a little background first for the less fortunate of you who haven’t heard about Igniter Space. Essentially, it’s a makerspace – a place where people gather and work on computing or other technological projects. From the outside, you’re forgiven for mistaking it for an electronics class.

  • 

  • 

  • 

  (more…)

  February 12, 2017

  IgniterSpace, KidsIgnite

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• Materialize CSS Autocomplete with AJAX

  At the time of writing this article, Materialize CSS framework’s Autocomplete widget didn’t work properly with AJAX calls. So I gave it a go myself.

  Ideally, the autocomplete widget should have the following features.

  • AJAX calls must be made only after a certain minimum number of characters are entered.
  • Requests must not be sent until the user stops typing into the box. This means setting a reasonable timeout to check end of typing.
  • If a request is already on its way when the user enters more characters, the existing request must be cancelled before sending a new one.
  • Clicking a result or outside the results list must close the list.
  • Certain keys should not trigger AJAX calls.
  • The results must be scrollable with arrow keys and selectable with Enter.

  The code looks something like this. A few important things are explained below it.

  (more…)

  November 23, 2016

  JavaScript, jQuery, Materialize, Web Development

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