continuously continuing review
Yesterday I crammed a chapter on continuous probability distributions. Let's see what I can remember before I open the book again.
the long and the shortcodes of it
I've just spent a little time trying to learn how to use Nikola's "shortcodes", and I've learned enough delicate things that I want to write them down for later. Not least, there are descriptions of the shortcode syntax on two different very long and identically-formatted pages, the Nikola handbook and the guide to extending Nikola.
improbable units
When you compute the Poisson-distributed probability of observing $k$ events in some time interval, you find
$$\begin{aligned} P(k) &= \frac{e^{-λ} λ^k}{k!} \end{aligned}$$
where $λ$ is the mean number of observed events. Here $λ$ needs to be dimensionless, because it's in the argument to the exponent and it's being raise to some power. But if you graduate to the exponential distribution, which describes the waiting time between successive events, then $λ$ acquires units of inverse time:
$$\begin{aligned} \mathrm dP(t) &= λ e^{-λ t} \mathrm dt \end{aligned}$$
Things that magically change units bother me. What's happening here?
on the phone again
What I'd like to be able to do here is to edit the blog on the phone. But that's going to take a fair amount of automation, because doing anything on the phone is hard.
However, I think I've gotten it.
everything looks like a π
Here's a cute little computation. Suppose you pick two uniform random numbers. What's the probability that their ratio rounds to an even number? It's straightforward enough to get "this is a sum that looks like it's probably famous." But it turns out that different definitions of rounding pull in different transcendental constants.
death is failure
In the probability of discrete events like coin tosses, you usually write $p$ to represent the probability of a success and $q=1-p$ to represent the probability of failure.
i'm on the phone
I've been trying to get to a point where I can edit my nikola blog stuff on my phone, and I am slowly figuring out how. Android does lots of careful sandboxing, and I have to work to undo it — especially since my preferred Android text editor, Markor, is intentionally unaware of any kind of sharing. I'm going to end up doing stuff in make, I'm afraid.
discretely distributed
Made it through chapter 5 of Hassett and Stewart, which details six discrete probability distributions whose properties I would like to be able to commit to memory. For each, where $X=k$ is the random variable where $k$ events are drawn from the distribution, the probability mass function, expectation value, and variance are as below.
markdown made easy
The installation for Jason Blevins'
markdown-mode is so
easy that I thought I wouldn't bother to write it down … but then I
looked in my note-taking place and I couldn't find it.
It's as simple as M-x package-install RET markdown-mode RET.
Everybody is using a package manager these days, and it's great.
staying uncovered
I went to search for a way to keep a window "always on top" of other windows, and I discovered Microsoft PowerToys. There's a bunch of things in there that I haven't explored completely yet.
long lines at the table
Working in an emacs buffer where I don't want to give up
whitespace-mode but I have a line that has to be long. The magic is
(setq-local whitespace-line-column 100)
who is that character?
If I want to type $a \times b$ without spelling out \times, here in
this lovely magical future, I should just be able to type ×. There
are different ways to do such things. What are they? Of course there
are websites. But I want command-line tools.
sharing ssh agency
For whatever reason, lots of default shell setups make it hard to share SSH agents and their list of authenticated keys. Here's my fix:
python from scratch
I seem to be setting up new computing environments frequently. Here's a recipe for making Python nice.
relative blind spots
Twenty-five years I've been using the Unix command-line for nearly all
of my computing, and it's only today that I learn about ln -r.
strange independence
The definition of independence of two events in a sample space is that the probability of the one doesn't depend on the other: $$ P(A|B) = P(A) $$ This definition feels necessary, but not sufficient. I can imagine at least two complicating cases:
tikz and latex for web illustrations
Today I wanted to make an illustration for which the correct tool was
tikz. I was writing for the web. Can I use tikz to put
stuff on the web?
HELL YES. There's a pdf2svg which gives vector graphics output.
watching for changes
One of the differences between the kind of text-mode/compile interface that I like to use, versus the WYSIWYG-style editors that the rest of the world has been using since forever, is that you generally have to do something or other in order to see whether your changes are having any effect. I've spent some time yesterday and today trying to come up with a mechanism to ease that transition, and I think I like what I have.
the clipboard
Reminded today of Windows's clip.exe, which reads its standard input
into the Windows paste buffer. That's the way to copy Linux/WSL stuff
to Windows. Mousing in the terminal window works ... sometimes. But
Emacs takes over the mouse, and the terminal copies my
whitespace-identifying characters.
The magic is M-| clip.exe, which runs shell-command-on-region.
the outlining continues
Yesterday I made good progress: chose two books that I have access to, outlined the curriculum from one of them (Ross), and did a problem. Yesterday it turned out that the Internet Archive's copy of Hassett and Stewart can only be used concurrently by a finite number of people, and it was unavailable by the time I got to it. But I have it this morning. So that's today's plan.
gathering reference material
Let's pull the list of probability textbooks from yesterday's post and see where they're available.
cow helps goat
bringing google drive to wsl
I wanted my Google Drive repository to be available as a filesystem under the Windows Subsystem for Linux. After a couple of false starts, here's how I've done it.
tornados, how do they work?
Having a look at this imgur video fragment1 and was reminded of an old question: what is it exactly that makes the funnel cloud visible? I had decided that there were at least two reasons, but this suggests a third one.
asymptotically approaching the starting line
The liveblogging felt very useful yesterday, so I'm going to try that again.
manic monday
A busy day today. Quick lists --- but on my phone, in Markor, a delightful Android text editor.
in which i develop courage
After some consideration, I think that I can keep this in public. It's going to take me a few days before I can post it, anyway, and I'll have some amount of time to build up the posting habit. Making a low-effort tool for writing from the phone will still be a challenge. But I want to move my goal from "write every day" to "write every day in public," even if I'm not expecting to have an audience.
It occurs to me that lots of this musing might have gone into my perhaps-someday-a-reference about nikola. But right now I'm figuring things out, and I suppose that should be more declarative than interrogative.
every new diary starts with metadiarying
Part of the reason that I started to convert to this web-output-friendly system is that I'd like to be able to write more frequently in a public-facing kind of a way. I think I have this sewn up (though I'm going to be tweaking things for a while). But I do have a little bit of a decision to make: do I want to use this as a personal journal as well? I feel super-squicky about that. While I would like to write in public more, I need to have a space that is safe for me to be dumb and annoying. Clearly the most probable outcome of me starting to post in public regularly is that no one ever reads anything that I write, unless I happen to direct them at it. But it's also the case that a desired outcome is for other people to discover that I write things. In that case, I need to stick to my old rule that I shouldn't write things on the Internet if I don't want them to appear on the front page of a newspaper.
that plant is half the man you are
I'm watching "Mugsy Explains" on "How flowering plants conquered the Earth".
One of the things this presenter does is to blur the distinction between "haploid organism" versus "diploid organism," instead of talking about whether more of the organism's life cycle is spent in a haploid phase versus a diploid phase.
a new blog engine
When I started this calendar year, I was pretty optimistic about how much teaching and creativity I would have, and I started trying to collect some doodads at a blog. I was being a university person, and I started at a university-supported blog. But it turns out that I'm not continuing as a university person, so now I have to do those things differently.