# The Spectre of Math

## November 27, 2012

### Frobenius method and Bessel functions

Filed under: Hacking,LaTeX,Mathematics,Teaching — jlebl @ 6:57 pm

I had occasion to talk about Bessel functions and mention the Frobenius method in my PDE class and I realized that I do not have any mention of this in the book. This was the section I did not quite get to when teaching at UCSD, so it never got written. Well, worry no more. I’ve written up a draft version of the section. This will appear in the next version of the book whenever I make it, though if you do have comments, do let me know. It’s good to catch typos or make changes now.

This brings the number of pages to 307 together with new delta function section and the number of exercises to 521. Yay!

This also made me realize that Genius did not have Bessel functions implemented. They were actually easy to implement as MPFR has them done. At least for integer orders and real values anyway. Then as my current working directory of genius was such a mess with trying to include LAPACK, I decided to remove LAPACK for now from the genius git. I think what I will do is link to the fortran version at some later point. It seems like the fortran LAPACK is available almost everywhere, so it should not be a bad new dependency. Much easier than trying to make the beast compile cleanly inside genius. Anyway, so Bessel functions will be in Genius, which I think I ought to make a release of soon as there are a bunch of other small changes to set upon the world.

## November 15, 2012

### New section in differential equations book

Filed under: LaTeX,Mathematics,Teaching — jlebl @ 7:44 pm

I have recently finally finished a new section on the Dirac delta function for the differential equations textbook. Take a look at the draft version. Note that this is a draft, so it could have typos and could still change. If you have any comments, let me know. Especially if you want to teach with it and would like to mention some detail I don’t mention right now. I will make a new version of the book including this section sometime in December, after semester ends.

In other news, the differential equations textbook is now apparently the standard book for Math 3D at University of California at Irvine. It’s nice if people pick the book to teach out of for their class, but it’s even nicer if a department decides to standardize on the book. The real analysis book is for example the standard book at University of Pittsburgh, and they even made their own changes (adding some extra material), which is a really nice example of what can be done with free textbooks.

I also added Google Analytics to the pages so I can see where the traffic is coming from. If someone uses the books by printing out a copy for students or putting a PDF on their site, I can’t quite see it, but if they simply link to my site it’s fun to watch the traffic. As the differential equations book has an HTML version, a lot of students seem to use that rather than the PDF. I assume the PDF is just downloaded and I don’t see traffic afterwards, but when they are using the HTML version, then of course they keep hitting my site. So currently there are several classes at Irvine and two classes at University of British Columbia that simply link to my site and I get lots of traffic on the HTML version of the book. These students using the HTML version takes up a large proportion of hits to my site. If you look on the map of which cities hits are coming from, there are two big circles, one over Irvine and one over Vancouver, and then lots of other smaller circles mostly distributed all over, mostly over english speaking coutries.

I am thinking I should make an HTML version of the real analysis textbook, but it’s quite a bit of work to set things up for tex4ht, and always quite a bit of work when making a new version so I have not yet gotten around to do it. Also I am more worried about formulas coming out correctly. It would be nice to get something like mathjax working with tex4ht. Or some other solution, but I don’t want to maintain two versions so it would have to take the LaTeX source and produce the HTML perhaps with a different style file. Anyway, for now it is images for equations, which do look bad when printed, but look OK on screen.

## January 13, 2011

### Vim, Evince and forward and backward LaTeX synctex search

Filed under: Hacking,LaTeX — jlebl @ 11:35 pm

I was finally fed up with not having forward and backward search in vim so I hacked up the python script that was in the gedit synctex package to do what I needed. The result is evince_vim_dbus.py (GNOME 2.32 version) or evince_vim_dbus.py (GNOME 3 version old LaTeX) or evince_vim_dbus.py (GNOME 3 version that works with TexLive 2011). Copy it somewhere into your PATH (say ~/bin or /usr/local/bin). The first argument is EVINCE or GVIM. If it is EVINCE then it works just like the evince_dbus.py from the gedit synctex package. So to do forward search you add something like the following to your .vimrc file. This uses the LatexBox set of vim macros, which is pretty unobtrusive and kind of useful

function! LatexEvinceSearch() execute "!cd " . LatexBox_GetTexRoot() . '; evince_vim_dbus.py EVINCE "basename ' . LatexBox_GetOutputFile(). '" ' . line('.') . ' "%:p"' endfun command! LatexEvinceSearch call LatexEvinceSearch() au FileType tex map ls :silent LatexEvinceSearch 

Make sure to compile your latex file with pdflatex –synctex=1 thefile. Now to jump to the right place in evince just type \ls in vim at the right spot. For vim-latex I assume something like the following would work though I have not tried so this may not actually work:

## September 10, 2009

### More sketch fun and more textbook fun

Filed under: Hacking,LaTeX,Mathematics,Teaching,Technology — jlebl @ 10:33 pm

I have to brag. Here are some more fun sketch pics. These are probably very close to what we’ll actually put into the paper. Marketa said that the second one looks like bublanina.

On not really related note the rate of downloads for my diffyqs notes is rising in the last week. I think I’m detecting the start of semester for many US colleges. I bet it will increase even more once the fall semester/quarter starts everywhere.

Now on related note, I’m typing up my notes for math 444 here, which is basic real analysis. So I’m writing another textbook: really baby analysis. Take baby Rudin and make it a lot less ambitious. If I were really crazy I could also take my sort of typed notes from last semester’s basic linear algebra and make those into a textbook … some other time I think, I didn’t really like the syllabus for that course, so if I were to make a textbook there it would differ more from the course here at UIUC.

## September 9, 2009

### Playing around with sketch 3D

Filed under: Hacking,LaTeX,Technology — jlebl @ 10:36 pm

We need figures for our latest paper. And the figures have to be of 3D things. So I’ve been playing around with sketch 3D, and so far it is working pretty well. It’s a 3D modeling language that compiles into latex.

Cool huh?

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