Below you will find pages that utilize the taxonomy term “Maths”
Playing with stable diffusion on your own machine is great.
This has been a really tough week.
I was on J on the Beach, so skipped last weekend.
A 2-week’s worth of readings means a longer than usual list, as usual.
Next week I start a new job 😮
Having to tweak a presentation for the Data+AI Summit time constraints has eaten all my disposable free time, hence the posting hiatus and this being relatively short.
My days are consolidating into piano, work, VR, piano, sleep, loop
Sweet, sweet holidays.
Not sure what I did this past week aside from finishing a post: I read very little.
The last of 2020.
My reading list is at less than 10 items, so now my readings posts will hopefully look closer to watchings. My watch-later list is at more than 90.
This is a short edition.
I am having a very hard time finishing my summary of the RDD paper.
I have been on holidays, which has resulted in a lot of reading, mostly books.
I am on holidays (starting yesterday)! Two weeks of probably more programming than usual 🤣
I should remove the Weekly moniker of these posts and emails. They are done when they are done. Enjoy!
I was a week off, and this delayed this post by a week. So, this is a long one: have fun for the 50th edition!
An early one: For the first time in… not sure how, I’m going to be a whole week off. Which implies no computer.
Spark 3 is here! Rejoice!
Another hard push at reducing my reading list. At the current pace I may not write many more of these posts.
I made a hard push to clean up my reading list, deleting a lot and reading another lot. It went from 369 items to 99 🎉
Writing generative stuff is eating away at my free time, reducing reading significantly.
The lack of commute is very hard on my reading, and I have also been working on several projects that have eaten into my reading/writing time.
The full lockdown edition. Almost no engineering ¯\_(ツ)_/¯. The lack of commute is hard on reading articles.
The stay at home edition. Stay safe these days, and remember to wash your hands and keep your distance.
No specific theme this week, but feels more data engineering heavy than lately. As it should. Oh, and beware door knobs, they can bring evil.
Update on read books this year, I had forgotten on my previous posts.
Skipped ehem a few weeks (I can blame one on my birthday).
I have been on quite the hiatus, making this more of a readings of the month edition. Sorry!
I have been pretty busy lately, and although reading doesn’t stop, my writing sometimes takes a hiatus.
Data engineering, adtech, history, apple. Expect a similar wide range in the future as well. You can check all my weekly readings by checking the tag here . You can also get these as a weekly newsletter by subscribing here.
_This week is a bit light on technical content because I was attending Scala Days 2019 in Lausanne and I had enough with the talks. _
Software engineering, psychology, history. Expect a similar wide range in the future as well. You can check all my weekly readings by checking the tag here . You can also get these as a weekly newsletter by subscribing here.
You know how you slip once on a habit and everything goes crazy? Well, I’ve been 4 weeks without writing these, so here’s the accumulated reading from 4 weeks. Because, even if I don’t write it, I read a lot anyway. Also, there’s lot of interesting content this “week”.
Sorry for the delay, Sunday was my birthday (also, Elmo’s, and The Day The Music Died as well) and I spent the day without access to a computer.
Software/data engineering, languages, writing. Expect a similar wide range in the future as well. You can check all weekly readings by checking the tag here.
The year has ended, what has been going on?
I had always wanted to play with Processing (after leafing through The
Processing
Handbook and
Visualizing
Data
some years ago). My general dislike for Java or the JVM made me just play a
short amount of time with processing.js something around 2011 (there was a
native processing.js application for iOS, I used it for a while on my iPad and
iPod Touch).
Almost two months ago (time sure flies) I attended for the second time the conference Scala eXchange, one of the largest Scala conferences in the world, and which happens to be 1 tube stop from the office you can find me from time to time in London.
I am trying to make these posts a tradition (even if a few days late). I thought 2016 had been a really weird and fun year, but 2017 has beaten it easily. And I only hope 2018 will be even better in every way. For the record, when I say we, it means Laia and me unless explicitly changed.
Some of the links are affiliate links to Amazon. I only recommend what I use.
At last February. Finished my PhD dissertation, so can add Dr. in front of my name when ordering a Gatwick Express train ticket. Also makes for a cooler email signature. So far has been the only differences I’ve seen in the year
Work February-December Started working as a consultant in London, almost the day after delivering the PhD presentation.
Started a long time ago. It was supposed to be about a phenomenon leading to chaos: separatrix splitting. I got a research grant. I worked on holomorphic dynamics. Travelled. Presented. Too many roadblocks with the separatrix problem. Switched topics. Welcome to a different new world, infinite dimensional dynamical systems. I read the literature. Researched, proved some things. My grant ran out. I worked. A lot. Too many times I considered giving up.
Back in the days of yore, when I was switching between my Windows machine and a Linux machine, I remember having SyncTeX active in my Windows machine. It was a wonderful experience: SyncTeX lets you click anywhere on a generated file from LaTeX and gets back to your editor, to the place generating where you clicked. This was extremely useful, specially later on when you need to adjust many formulas to fit and you need a bit of back-and-forth-ing.
Is this line noise?
⍉' *'[⍎'1+0<|z',(∊150⍴⊂'←c+m×m'),'←c←(¯2.1J¯1.3+(((2.6÷b-1)×(¯1+⍳b))∘.+(0J1×(2.6÷b-1)×(¯1+⍳b←51))))'] Nope. This is not line noise, but a complete APL program to display the Mandelbrot set in glorious ASCII, with asterisks and spaces just like Brooks and Matelski did a long time ago while studying Kleinian groups (it’s a short paper, read it someday). I’ll explain in (a lot, I hope) detail this line in a few moments. So, what’s APL first?
A few months ago (woah, so long already) I had an impulse buy: I purchased a circular slide rule from Etsy. It was cheap, and I had always wanted one, so… I just bought it (a neat addition to my Addiator.)
I guess if you are geeky enough to read mostlymaths.net, you know how a slide rule works. Although I knew how to use it, getting to grips with it took a little while.
Taken from Flickr
In case you have not realised it yet, I’m a pretty prolific reader. Online reading (and having an iPad) have slowed down the number of books I read in a given year, and I don’t go to the lengths of my girlfriend (who is about to reach her goal of reading 102 books in this year,) I’m nevertheless a frequent reader.
This year I’ve read several good books that I’d like to share with you, after all, if you are reading this probably our tastes overlap.
This was computed using PVM and the full PDF generated is 16k pixels wide
Today is Iceland’s National Day (commemorating their independence day and the date of birth of Jón Sigurðsson), and to commemorate it I share this image with everyone.
I computed this image a long, long time ago (using the Distance Estimator Method, paralellised with PVM using 16 computers, it took just 2 minutes). The full file is a 30MB pdf, which I printed large-size (2 meters wide), and sits in my office.
Last Tuesday I presented a talk in a congress, here in Barcelona. This post is not about this talk, but about the Mac remote and Apple’s “problems”. If you are interested, you can download the talk here, anyway.
As the congress was local, instead of using my netbook for the talk I brought my MacBook. Instead of using arrow keys, I could use these fancy Apple remotes. Good plan… at the moment.
Next week is the final exam of the course I’m giving, Numerical Analysis. Classes finished before Christmas, and this week is for students questions. I had one of these sessions this morning, when a pair of students came with a few questions related to the problems I solved on the blackboard.
All were quick to solve, until one simple question arose, concerning a trivial problem in Calculus 1 (or Analysis 1, as we name it here).
From
The Design of the Emacs Logo
As you may already know, emacs is more than a (cross-platform) text editor. Some say that it is like a whole operating system (and some devil worshippers say that it lacks a good text editor…). For the next 30 days (starting December 1, 2010) I’ll check it as well as I can. I will work just with emacs.
You can check the challenge updates below:
Hi readers! (woah… 235 already! I’m so glad you’re here with me!)
This week I’m in Warsaw for a workshop (as I already commented in last post when I talked about the poster I am presenting).
I was expecting to use idle hours between talks and afternoons to write posts and post a little… But my internet connection is inexistent. This post is coming from an open wifi connection, which gets connected and disconnected at random, and when at its peak, just makes 3Kb/s.
This week I’ll be in a workshop on Complex Dynamics in Warsaw, and will present a poster titled Approximating bifurcation loci by zeros of functions. This is heavily based on a poster I presented last year in Copenhagen (titled Sets approximating regions of instability). The underlying work in progress has changed quite a bit since then, but this does not show in the poster. I just solve some problems in the exposition, from the questions I got back then.
Lately my pile of papers to read has been growing steadily, and I’ve done very little to read all that stuff marked with “will read someday”. It had to come to an end, and it did with my previous Task Bankruptcy.
Reading research papers can be a huge waste of time… Or end up in forming big piles of To be read someday. The problem is, usually someday never means today.
And e/2 Appears from Nowhere! (Follow up to 'And e Appears from Nowhere')
3 minutes read | 464 words
You may remember a post I wrote a month ago titled And e Appears from Nowhere. It was based (through some blogs I read) on a footnote from Prime Obsession(Amazon affiliate link) by John Derbyshire. The footnote reads:
Here is an example of e turning up unexpectedly. Select a random number between 0 and 1. Now select another and add it to the first. Keep doing this, piling on random numbers.
Two weeks ago it was the beginning of this years lectures. Currently I’m solving problems in the blackboard, 2 hours per week and take care of one computer lab (programming in C, but they have already done a C programming course and another course of numerical computations with C), all for our Numerical Analysis course (7th semester). This is the same schedule I had 3 years ago, also last year I had one computer lab each semester.
Yacas is an advanced computer algebra system, with its own programming language and a lot of handful operators available.
It comes handy when you need to do that odd symbolic computation which is too big to handle by hand (or you are plain lazy).
By looking at the wikipedia entry, I discovered an startling truth: as of 2009, yacas is no longer maintained.
I should have guessed, because yacas does not compile out of the box (the program needed to generate the manuals does not compile), and this led to some naïve patching (just removing all instances of said program…).
As I posted in Best Posts I Have Read in June and July, I liked a lot a numerical experiment in Re: Factor, a blog about learning the Factor programming language. The idea comes from another blog, this time about Clojure (a Lisp dialect running in the Java Virtual Machine), based on a footnote from Prime Obsession (Amazon affiliate link) by John Derbyshire. The footnote reads:
Here is an example of e turning up unexpectedly.
Most of you may not know who Vladimir Arnold (Владимир Арнольд, also written as Vladimir Arnol’d) was, but for me his death on 3rd June 2010,was some kind of landmark. I own two books by him (Mathematical aspects of classical and celestial mechanics [1] and Mathematical methods of classical mechanics [2]), and are quite high in my list of most checked books, at least when I was starting my journey into the realm of dynamical systems.
A week without writing here. A week with little thesis related work done. But it has also been a week with ideas and things and such. You know, two weeks ago I was in Dresden for a conference. Lots of parallel sessions, and quite a few time to think. This post is mostly a digest from my life bookmarks for these two weeks.
Several complex dynamic ideas: Unrelated to my thesis, but I’ve been thinking about them these days.
As I wrote in a previous post, I’m on my way to learn forth, and to do so, rewrite my Lispy raytracer into a.. Forthy raytracer. Of course, the first steps are deciding on some implementation ideas.
I decided to allocate a few global variables (for “current point”, “current vector”, “light source”, etc), to avoid too much clutter in the stack. This way it will be cleaner, maybe even cleaner than my Lisp version.
The easiest way to debug: valgrind with the most powerful text editor: emacs A few days ago my office mate told me about the great debugging tool known as valgrind. Before I have been using the great pairing of emacs+gdb to debug segmentation faults and memory leaks… Now I would never use gdb for this. Moreover, I found a way to somewhat use it from within a shell in emacs to allow fast error browsing.
Maybe you remember my previous post about detection of copied assignments? Well, now I can say it succeeded. CJuicer is a flex script, generating a lexycal analyzer with a rudimentary parser of C code, it outputs a PostScript with the “logical tree” of loops, function calls and conditionals. Same trees, copied assignment (unless it is simple code, then almost everyone writes the same), without problems with changing names of variables. Thus it could beat diff.
If you liked it, leave a comment, digg, stumble
or whatever you feel like doing
Stochastic hill-climbing algorithm to approximate a picture by triangles (algorithm and source code). This image contains 48 images out of 1000, from iterating for 11000 generations the evolution code. The source image is the last square in the tile set.
Bon Nadal!
Feliz Navidad!
Merry Christmas!
Joyeux Nöel!
Buon Natale!
Frohe Weihnachten!
Mutlu Noeller!
As I said in a previous post, I am looking for some way to detect copied code. I have now a working prototype of a “code juicer”. From a C file it creates a set of PostScript files (well, almost, as they need postprocessing) which are later processed and selected to print. As an example, here is the output applied to a Runge-Kutta-Fehlberg 4-5.
It is something like an execution tree, with function calls squared, and different slopes for if, for, while clauses.
Pieces of an ENIGMA machine, from Flickr
Assume you have a set of alumni, which are due an individual programming assignment. All have the same assignment (as it is hard to come up with several), and it is hard enough that copying from each other passes for everyone’s mind. As a teacher, how do you detect this?
From my point of view, there are fundamentally two different kinds of copy:
As you may remember, I spent quite some time this August with Lavaurs algorithm for the topological identification of the circle corresponding to the Mandelbrot set. After that, I spent quite some more trying to do pictures of external rays to show side by side. I was not able… and then found Mandel.
Thanks to Mandel, LISP and my Lavaurs code
Really nice program, with lots and lots of options (and I met the programmer, which happens to be also mathematician, we met at a conference).
As you may already know, I presented a poster at a conference recently, and did the set up with Scribus, the texts with LaTeX with the Beamer and Beamerposter packages.
Setting up
Note from 2019: I can’t find the final version of that poster, only a modified version from a few months later for another conference.
The first piece of advise, is to set page guides where needed (in the Page menu, you can put them at a certain numerical place, and then move them along) and then Snap to guides in the same menu.
With Sketchbook Mobile
The concepts of “future”, “job stability” or even “location” are quite fuzzy when in Mathematics. I think I don’t know any PhD student who knows what he will be doing in 3 years, what he will be working on (not what he will be researching, but working…) or even where he will be.
1-2 years of Master+Master thesis
2-6 years of PhD thesis (3-4 years PhD grant+maybe some associated professor, 1-4 years)
København, Denmark
Related posts:
ParseList(ScrambleList(Relateds(Maths)),5)
Last weekend I attended a conference in Denmark, and a colleague I met there showed me the logo of his University. It is supposed to be a coral… but he said in every party they turn it 270º, so it is the “angry elk”.
Related postsParseList(ScrambleList(Relateds(Maths)),5)
Mathematician, Linux user, already had an iPod (iPod nano), recently bought a netbook. Why did I buy an iPod touch?
Just 5 excerpts of it
Related posts:
And “e” appears from nowhere!9 programming books I have read and somewhat liked…
C code juicer: detecting copied programming assignments
Cron, diff & wget: Watch changes in a webpage
8 reasons for re-inventing the wheel as a programmer
Approximating images with randomly placed translucent triangles
ParseList(ScrambleList(Relateds(Linux, Programming)),10)
Emacs fun, in other words. This weekend I’m writing some programs in C, to review major problems before my students ask. Yesterday I finished the part due Wednesday (for them), and today I tackled the final part. But there is some bug somewhere… I always miss on such matrix-here-matrix-there-solve-that.
Today, after battling for an hour, I realized I missed the “intellisense” part of CEDET, and started to install it here in MacOs, and “there” in my netbook.
or the trouble with hard-coded paths and ineffective menus.
Cross platform page-layout software:
Scribus. Now with more LaTeX
I am supposed to present a poster in a conference, about some work I am doing. I asked office mates about what they used… A Mac user suggested Pages, and I asked a more Linux oriented, LaTeX savvy, and he told me: forget about LaTeX and use some WYSIWYG program, you’ll save time and effort.
Althouh I use AucTeX, which already has nice quick-writing techniques, I have found emacs' abbrev-mode together with skeletons are a nice addition to it, allowing me to be really quick at writing LaTeX. The included examples to use dabbrev and skeletons are for the mathbb and theorem environments.
Sample usage: When I write \mbb, and then open the left {, mbb gets expanded to mathbb… so I have \mathbb{ as needed.
When you are about to send a file to ArXiV, it greets you with the following confirmation message, just before the “Click here”:
Now Processing Submission
Read carefully the information below, recite aloud the English alphabet backwards starting from Z, breathe deeply, read carefully the information below once again, and then with a suitable pause (at least 10 seconds) you should
CLICK HERE TO CHECK STATUS
It made me lough quite a bit a few months ago :)
Last year our department got a nice and shiny Xerox WorkCentre, with scan+mail capabilities. Wonders of technology, now I can scan those chapters I use from books that weigth tons. But… of course, the machine scans two pages each time, and thus creates a double bound PDF.
And this doesn’t work well with my way to print booklets, so a working solution was to use ghostscript and ImageMagick from the command line.
My month, starting
For the last two years, I have been really happy, living without a definite calendar. I just knew I had a meeting with my boss “next Monday”, or had a workshop somewhere “in the last weeks of January”. But these days I’ve come to realize I just need a calendar now… And finally managed to mix org-mode's events with standard emacs calendar+diary views. This calendar is emacs calendar’s mode standard one (I love its looks) but harvests information from org-mode’s headlines and timestamps.
From flickr
September is to months as Monday is to weekdays
September is again here, like a new year in more than a sense. I have no new “New Year’s promises”, since the beginning of the year. In fact, most of the things I wanted to do are already done, on the way to be done or I gave up. Well, let’s summarize what I shall do these three months to end 2009
Have you ever wondered how to take a screenshot remotely, via the command line in a Linux system? Here is a way to do it. At the bottom you can also find a script to move it to the root of your personal page (if you have) to open the screenshot in your browser.
I have a Lisp program running inside Slime (The Superior Lisp Interaction Mode for Emacs) in an emacs instance running in my office computer.
These days I’ve been busy programming a version of Lavaurs algorithm for the idenfication of circle chords: the abstract Mandelbrot set.
The images don’t look like much, but the output of the program is nicer: it outputs an Encapsulated PostScript file which looks sharper. But when converting to png with ImageMagick some distortion appeared.
Lavaurs chords, depth 13 cutoff
Lavaurs chords, depth 5
Lavaurs chords, depth 13
Taken from Flickr
Sometimes I view mathematical knowledge as a desert. Full of sand, some pebbles, some rocks. You can get easily lost in this dry sea, but you can also find a place to stay and add. And now, I can say I have added my small grain of sand: An entire transcendental family with a persistent Siegel disc (link to the preprint version in ArXiV). My first article, now officially “Awaiting Editorial Assistant Processing”.
Lavaurs algorithm on course
Like almost every year, August comes with a lot of pending To Do lists… This year, it is choking full, mostly of work related issues, and some unknotted threads waiting to be finished. And in two and a half weeks I’ll head for Paris, and then my “vacation” is over.
Yesterday I wasted my morning: bought my orange belt, set up the external monitor for my netbook, configured the printer, fotocopied two pages of a book and drank an horchata with a friend.
Princeps Mathematicorum
Old 10 Deutsche Mark banknote. Gauss depicted along with a normal distribution and 5 historical buildings in Göttingen. The most visible, St. Jacobi’s Church (Jacobikirsche).
As you already know, I’m just in the middle of getting a thesis done. This means quite a lot of hand-written papers, full of definitions and on top of it all a lot of notational problems. I have quite a few similarly named spaces, with its corresponding norms… It is a mess.
When I had already proved my “first” theorem (in the thesis context, I mean… I have a paper soon to be published :), I started LaTeXing it.
I feel like I contributed something. I rewrote Wikipedia’s Siegel disk page, adding references and images. It is now quite dense… Ill have to re-read it to simplify it several times. Or someone else… Wikipedia’s wonders.
Snapshot! (Via Paparazzi!)
As I already did with Douady Rabbits, here is another dynamical plane, this time corresponding to a Siegel disk in an entire transcendental family in a parameter corresponding to a polynomial-like region.
Siegel disk in an ETF, available below as wallpaper
Siegel disk for desktop background 1280x800
Siegel disk for desktop background 1024x768
You can also buy a poster version here.
If you liked it, or have whatever else to say please leave a comment, digg, stumble or whatever you feel like doing.
Image from Flickr
Arrow’s impossibility theorem and related results
Background: Let K={A,B,C…} be a finite set of alternatives (maybe political parties), with more than 3 items. Let’s call transitive preference a way to sort all these elements, with draws possible. It’s just a funny name for a vote, in the more general sense as we can split our vote (Let A have 0.5, B 0.25 and C 0.25 of our vote).
This evening I was bored at home, and decided to have a look at my old Lisp raytracer… a project that just went idle a year ago. I picked up another programming project I had idling for a long time (an emacs lisp project, to interact with my console-based fractal drawers). I had a coding breakthrough that time, and managed to advance quite a bit in a little time, so today I tried again.
Sometimes I feel like a character from a RPG (or NetHack), where you have a certain level and experience, and as you advance killing monsters, your experience points go up, your level eventually rises and your enemies turn harder.
I guess life (or at least a mathematician’s life while doing his thesis) is more or less like this… Enemies appear, you overcome them, and as you advance, they get stronger, bigger and thicker.
Softcover binding your own books is easier than you think
Bookbinding for dummies As of late, I have been printing quite a lot of long mathematical papers, and a few free pdf-books, or tutorials. And I wanted them properly bound, but didn’t want them so much as to pay for it. A few months ago, I found this tutorial on hardback binding. Although the tutorial, method and result are great, it is quite a lengthy effort.
Get arbitrary size fonts in LaTeX You have probably wondered how to get really big fonts in titles, or anywhere in a LaTeX document.
\usepackage{fix-cm} % Allows for Computer Modern fonts of arbitrary sizes
…
\fontsize{60}{70}\bfseries A SAMPLE
…
You are done. Easy, wasn’t it? You may also be interested in ParseList(ScrambleList(Relateds(Latex,Linux)),5)
I have been experimenting with exponential-power potentials in my fractal images as of late, and by far the best results have been these. You can download it as a desktop wallpaper, hope you enjoy it. This Douady rabbit appears as a capture zone for a critical value in an exponential family.
Douady rabbit in an exponential family, available below as wallpaper
Douady rabbit for desktop background 1280x800
Douady rabbit for desktop background 1024x768
The first day, on our way to the Parador at Carmona (Sevilla, Spain) this is what we saw.
If you are printing a lot of… well, anything, sure you would love to make booklets out of what you print. If you happen to be a mathematician, you sure are printing lots of papers with more than 20 pages, which turn to 10 unmanageable pages when double-sided. But making a booklet allows you to turn them to just a little folded thing that you can read easier.
When printing in MacOSX you can print booklets, but they are supposed to be cut, not folded across as you would do to bind a book.
Two context-free grammars for a Merry Christmas. Rendered with Context Free
From 5 November to 9 November took place the (second) Fall School in Holomorphic Dynamics. Three fine speakers came (Walter Bergweiler, Agnieszka Badenska and Kari Astala), each one giving a course about a different topic in 3 sessions of one hour and a half. The only course I completed was the one Walter was giving, as it was the most interesting for me.
I talked on monday afternoon, but my talk was a mess.