The Spectre of Math

April 16, 2014

Putin vs. Godwin

Filed under: Politics — jlebl @ 5:18 am

I call Godwin’s law on Russia.  So, by the rules of Usenet, Russia has lost the argument.

I think the security council should adopt Godwin’s law.  Any time you call anyone a Nazi during an argument, you lose your veto power for that issue.

February 27, 2014

Numbers

Filed under: Economics,Politics — jlebl @ 12:43 am

When reading news, one should do some quick calculations to test for ridiculousness.  It really makes reading news far funnier.  Let us look at the 19 billion dollar deal where Facebook bought WhatsApp.  It is especially hilarious if we interpret this as how much do we as a society value WhatsApp versus some other things.  These are based on just quick googling, but they are for just eyeballing the thing, not to be taken exactly.

1) Minimum wage hike.  There are about 3.6 million people at or below mimimum wage [1] (2012 data).  If we suppose that they would work 250 days a year for 8 hours a day, the current $2.85 proposed hike ($10.10-$7.25) would amount to 2.85 \times 8 \times 250 \times 3,600,000 = 20,520,000,000.   So about the same.  Facebook could have paid everyone on minimum wage the hike for a year.  But of course I’ve overestimated I doubt everyone on minimum wage works 8 hours a day 5 days a week.

2) NASA budget is about 16 billion in 2013 [2].  So WhatsApp is actually worth more than all that NASA does in a year.

3) Nominal GDP [3].  Czech Republic is about $196 billion.  Ten WhatsApps is the GDP of the whole country of 10 million people (where WhatsApp has 55 employees, so 10 of them have 550 employees).  Jamaica has nominal GDP of $13 billion or so.  WhatsApp is way more than that.  OK, you say, that’s just one year.  Suppose that WhatsApp (what it does) works out to working for 5 years before it becomes obsolete.  That’s 3.8 billion per year.  The GDP of Cayman Islands is $3.3 billion.  And that’s where Facebook is taking its profits to avoid paying taxes [4].

4) The University of California budget for 2013-2014 is $6.2 billion [5].  WhatsApp would fund the UC for 3 years.  WhatsApp apparently produces so much good for our society that it equals about the output of the entire UC system for 3 years.

[1] http://www.bls.gov/cps/minwage2012.htm

[2] http://www.nasa.gov/sites/default/files/files/FY_2013NASA_OperatingPlanEnclosure1_13SEP2013.pdf

[3] http://en.wikipedia.org/wiki/List_of_countries_by_GDP_(nominal)

[4] http://www.theguardian.com/technology/2013/dec/05/facebook-tax-cayman

[5] http://regents.universityofcalifornia.edu/regmeet/nov12/f1attach3.pdf

February 3, 2014

New computer, still with MATE …

Filed under: LaTeX,Technology — jlebl @ 7:53 pm

I just got a new work laptop, the Dell XPS 13 developer edition.  Even for a day installed GNOME 3 on it.  Then I realized that I can’t work with two different desktops at the same time, so I went back to MATE.  I can’t change my work computer to GNOME because the dual-monitor support is terrible in GNOME shell.  Oddly it seems that dual monitor is a corner case for GNOME devs now.  Strange as Linux is more used in the “workstation” market than “home desktop” market, and if I look around the offices here, whoever can (has funding) does have a dual monitor setup on their workstation.  GNOME sucks as a workstation.  It might be fine as a place to launch a web browser, email, chat, whatever it is that kids do nowdays.

The other thing is that this has a pretty high DPI, and EVERY desktop kind of sucks at this.  I don’t think that mid 30′s is too old to use computers, but there are things which are definitely harder on this thing and require squinting.  My eyesight is not what it used to be, but it’s not that bad.  I can get most (but not all) fonts to be bigger.  But for example chrome I can’t get to be bigger everywhere, that is, yes on the webpages, but no on the tab headers.  Also UI elements in other things are tiny, like scrollbars are suddenly hard to hit because they are tiny.  Why don’t these things also scale?  That’s annoying.  Smaller resolution is OK, but blurry and sucky.

Another annoying thing is this really godawful thing called a click-pad.  It makes the assumption that just because you can do something, you should.  So the top of the “buttons” are now also place where the “mouse” moves.  So by pressing the button I am also moving the mouse, often clicking somewhere else.  So now if I want to click on something two things happen: 1) the mouse jumps somewhere completely different 2) or I can’t hit it.  Put that together with the small controls and you have a recipe for disaster.  I continually click on things I don’t want to.

Ahh well … There are nice things about the laptop too, like the size, and the case.  Though it doesn’t have a lock hole, which is really anoying … in a coffee shop, am I supposed to take the laptop to the bathroom with me?  I know it’s small, but taking your laptop with you to pee is kind of weird.  Oh yeah … ended on another complaint …

October 1, 2013

Installed MATE, bliss ensued

Filed under: Linux — jlebl @ 8:25 pm

A couple of crashes of GNOME shell, including yesterday stealing my keyboard focus and refusing to let it have me back, and then the mouse not working for a while … Together with the shell just generally driving me nuts, was enough to type “installing mate on ubuntu” into google.

At least this is sort of GNOME, so I don’t feel like a “traitor to the cause.”  I do like one feature of gnome-shell and that’s the window stacking if you press it against the sides, so I can have two side by side windows easily.  On the other hand, I have multiple desktops on my second monitor now.  Yay!  It feels good to be back in saner and less-flashy times.

September 26, 2013

More GNOME gripes

Filed under: Linux — jlebl @ 3:45 pm

Since I could install new enough Ubuntu to easily install GNOME 3.8 and hence use Classic mode, I am now for the last month or so using GNOME shell at work.  Now I just got a wonderful new computer with two screens that I just installed the same setup on.  And I have to say that there were several things that drove me absolutely crazy yesterday.

  1. I can’t tell a difference between focused window and unfocused window in the default theme.  I kept typing into the wrong window leading to all sorts of bad things happening (sucks having what should go in a terminal being typed into your grant proposal, and then having to hunt it down, or perhaps typing something into your grant proposal and instead typing it into gmail with keybindings turned on and hence archiving a few unread emails that you have to hunt down without actually knowing what they are.)  I found a different theme that does the only sane thing of making the title bar really blue when focused and really gray when unfocused, bad thing is, that such a usability issue is only in the tweaks, and that the theme is ugly.  Good thing I value actually working over how nice the thing is.
  2. Printers!  I can’t add the printer.  Instead of easily adding a printer I get presented with a dialog where I can’t do anything, it lists some random printers usually in other people’s offices.  The “community printer” on this floor is not listed.  Hmmm … what is the address … I go to the old computer (also with GNOME 3.8) look into printers and I can’t find detailed info about the printer.  After about 5 minutes of fussing around I remember to look into the cups text config file.  Ahhh …  now I have the address of the printer.  OK, so how to add it.  On the new computer, click “Add printer” and then where do I put in that address.  Putting it into the search bar yields nothing useful, pressing enter adds someone’s personal printer.  OK fail … After further number of minutes I give up on the gnome printer thingie as totally and utterly useless.  OK, but where is the good old (or bad old, but at least somewhat usable) printer setting application.  Now my memory is still what it used to be: bad.  So I can’t remember it.   It doesn’t appear in the gnome-shell, typing “printers” into overview mode only brings up the totally useless gnome version.  OK, have to google, after a few minutes I find it.  I have to start “system-config-printer” from the command line.  There although the interface is also bad, I can actually add the printer.  Damnit, about a decade ago in GNOME I could do all this with just mouse clicking.  With this new really simple-to-use GNOME I can’t, I have to use command line.  To add a printer!  This went from bad UI to unusable UI.  Not only that, I can’t get to the usable UI from the UI even though it is installed.
  3. Multiple monitors:  GNOME shell does something weird with multiple monitors.  It treats the second monitor as sort of “scrap space” that you don’t really use, so there are no multiple desktops, there is no bar on top …  I know there is a setting in tweak (the fact that tweak exists is a failure of design to begin with), but the setting doesn’t seem to work.  All it does is to make the extra monitor slide around, but there is still just one desktop on the extra monitor.  It feels like this was designed by somebody using the second monitor as a presentation display for a laptop or some such.  It doesn’t really make sense for a two display workstation.
  4. The status menu is now easy to miss and skip by mistake into the second monitor.
  5. The overview mode active corner is really damn annoying.  I keep going into it when wanting to press the back button on the browser.  Fitts law fail!
  6. No more categories in the shell overview.  Good thing there is the menu on top in classic mode.  I don’t search!  I click!  Mostly because I can’t remember what to search for.  Looking through a list of ALL application sorted by alphabet is rediculous.
  7. evince keeps crashing, and the dbus interface seems to have changed again so my synctex script no longer works.  This is really annoying when you have to get something done.

All in all, I am very unhappy so far, and getting unhappier and grumpier by the minute.  I think XFCE, for all its suckiness will end up being my work desktop too.

July 18, 2013

Kansas?

Filed under: Uncategorized — jlebl @ 2:21 pm

 

See anything wrong here?

 

kansas-state

July 12, 2013

MAA reviews, HTML versions, new sections in RA book …

Filed under: LaTeX,Mathematics,Teaching — jlebl @ 7:54 pm

Reviews

MAA has done reviews of both of my books: see here and here.  By the way, now they have been downloaded (at least the PDF) each from over 40k distinct addresses (approximately 83k together now).  Since it seems the web version of the diffyqs book is probably more popular than the PDF, there is probably another as many people who’ve used that.

HTML version of the DiffyQs book

Speaking of the HTML version.  After last release of the diffyqs book, I’ve worked a bit on the HTML conversion.  The result is using tex4ht for conversion and then a Perl script to clean up the HTML.  This is very very hacky, but of course the main point is to make it work rather than do it cleanly.  One of the things I’ve done was to render all math at double the resolution and let the browser scale it down.  Then to make things go a bit faster I’ve made the code detect duplicate images of which there are quite a few.  I’ve also been testing with data URIs for very small images, but they don’t quite work right everywhere yet.  They would cut down on the number of requests needed per page and surely eventually I’ll do that.

The supersampling has both positive and negative effects.  Printed version of the HTML now looks a lot better.  Not totally great since I currently have things render at around 200dpi rather than perhaps 300dpi, but it’s a reasonable compromise.  Also high resolution displays give nicer rendering.  The downside is that on a regular display the equations are fuzzier due to lack of hinting.

Of course MathJax would be the ultimate answer to the math display and that’s the ultimate goal, but I can’t make it work with tex4ht reasonably nice.  I am very picky about the display being 100% correct even if uglier, over being 90% correct and pretty.  Every suggestion I’ve tried so far was very subpar on output.  I can’t make tex4ht not touch all math.  Even then MathJax does choke on a few expressions I have in the file so things would require more tweaking to make it all work.

The requirements for math display I have is 1) I want to make sure that the same font is used on all math (that’s why I render all math as images).  2) I want the output to be correct and readable (which totally disqualifies MathML since even newest versions of all browsers do terrible jobs on all but the simplest equations, and even there).  3) I want the thing to be usable on as many browsers as possible.

I think eventually the solution would be to write my own tex parser that can read the subset of latex I use for the book and output HTML pages using MathJax.  This sounds simpler than it is.  That is, getting this to work on 90% of the input is easy, then things like figures, and certain math constructions get in the way.

Another possibility is to output svg instead of png for math using dvisvgm.  This keeps the problem of fuzziness on standard displays, but is really pretty when printed or on high resolution displays .  The downside is bad support (only very new chrome and firefox support this somewhat and even they have issues, and it crashes my android phone).  I think MathJax is a better long term solution, but it will take some work and probably a move away from tex4ht.

New sections in the analysis book

Something I have not mentioned here when it happened is that the analysis book got a bunch of new sections recently (the May 29th version).  These are all extra optional sections to fill up a longer version of the course (dependencies if any are marked in the notes at the beginning of each section).  There is a section on

  • Diagonalization argument and decimal representation of real numbers (1.5)
  • More topics on series (2.5)
  • Limits at infinity and infinite limits (3.5)
  • Monotone functions and continuity (3.6)
  • Inverse function theorem in one variable (4.4)
  • The log and exp functions (5.4)
  • Improper integrals (5.5)

I am currently working on multivariable chapter(s) that would come after chapter 7.  This will take some time still, I have about half of the material in a very rough draft, having massaged bits of my Math 522 notes into something that more fits this book.  My plan is for the book to be usable for a standard one year course on real analysis.

June 25, 2013

New Genius out (1.0.17)

Filed under: Hacking,Linux,Mathematics — jlebl @ 9:18 pm

Release a new Genius version (1.0.17) today.  See the website.

Main new thing is that it is using Cairo to draw now thanks to update to new GtkExtra.  At some point I should package up and document all the fixes/changes I’ve made to GtkExtra and submit them upstream, it seems that GtkExtra is now alive again.

May 30, 2013

Windows 8.1 innovations

Filed under: Linux,Technology — jlebl @ 4:35 pm

I’ve just briefly glanced at what’s new in Windows 8.1, probably because I am procrastinating right now, not because I am actually interested, not having any plan of ever using Windows ever again in my life.  It was really amusing that new features are apparently that you can open more than two applications at once and also resize them on screen.  So maybe Windows 8.1 will finally catch up to Windows 1.0.

I feel I’m taking crazy pills here, because almost everyone is really into this trend.  First make the interface really bare (but graphically intensive) to make it look like a smartphone.  Then reintroduce very restrictive versions of these features and tout them as great achievements.  Chrome OS also at some point caught up with the 80s and added stacking windows.  I wonder when Windows will finally get into the 80s.

And while basic features like window management appear an insurmountable challenge in the new “iphone app” mentality, putting up a clock on your screen eats more CPU/GPU and memory than it would take to guide a spacecraft to Mars and back.  Not even that long ago did a calculator application not require 3D acceleration to reasonably run.

Good thing I’m using XFCE here.  Let’s see how I start a calculator: My non-accelerated desktop means that if I press Ctrl-Alt-R (which is my shortcut for terminal … R used to stand for rxvt long time ago) I immediately get a terminal.  Then I type “genius” press enter, and I’ve optimized the startup so I get a prompt immediately, there is essentially zero wait.  I type in a calculation, and out pops the answer.  Now if I attempt to do this on my phone, or in GNOME using the native calculator, there are several long waits either when some random nonsense is loading just for me to start the app and then there are these useless animations taking up time.  So for example if I have a student in my office and want to just quickly (note the word quickly) calculate something about their grade, I would definitely not do it on my phone.  Even try starting the native terminal in GNOME, it’s a few seconds wait on my machine from the time I get to start it (click a button, or whatnot).  So much for accelerated desktop. Just trying to phone someone on my phone is often a lot longer process than it used to be in the 90s when I got my first cellphone.  There is hardly a lack of power in the phone, it is just that it is so skillfully wasted.

This younger generation today must be really really patient (compared to us old fogies … you know 35 is old when it comes to technology) to put up with this.

May 28, 2013

Computation update

Filed under: Hacking,Mathematics — jlebl @ 4:45 pm

On the scale of length of computations I’ve done, this probably counts as the longest so far.  If you look down a bit in the blog you’ll find the details.  I can now report that there is no degree 21 polynomial p(x,y) with positive coefficients, with exactly 12 monomials (the least it can have), such that p(x,y) = 1 whenever x+y=1, and such that xy is one of the monomials.  Now the conjecture is that there is only one such beast (up to switching variables), dropping the condition about xy, and the computation is well on its way to prove that.  That one monomial is a bit special since it appears in these sharp polynomials for a bunch of smaller degrees.  Anyway, a few more months and we’ll have the answer.

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