Technology on Peter V. Mørch's Blog

How to use Mathjax in Hugo

Sat, 24 Jul 2021 04:30:00 +0000

Hugo is the static site generator that this site is built with. This is how to enable Mathjax in Hugo so you can write LaTeX in your pages, as I’ve used e.g. in On the Economics of Streaming: Show me the money

Put this in the page source somewhere. I put it in layouts/partials/head-additions.html, but perhaps that is specific to the ananke theme:

<script src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script>
<script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script>

Now you can put this on your page and have it rendered like you’d expect:

On the Economics of Streaming: Show me the money

Fri, 23 Jul 2021 10:08:00 +0000

I’ve never spent as much money on music or TV and movies as I do now by paying my Spotify and Netflix subscriptions. But still artists apparently aren’t getting any money for their art. How can this be? Where is the money going?

Below I’ve done a back-of-the-napkin calculation. If all the premium money went to artists we should be listening 45.5 hours/month, but on average, we actually listen 25 hours/month. Which means that Spotify is keeping 45% of my subscription, and only paying 55% to artists.

Data Visualization: It Matters How we Show Graphs

Sat, 12 Jan 2019 12:19:47 +0000

Should we show graphs using horizontal lines like this:

Or using “slanted” lines like this? :

Perl: Schema for APIs with code generation?

Tue, 09 Jun 2015 23:09:33 +0000

Two things have occurred lately for me in Perl:

I’ve been bitten enough times by un(der)specified RPC and API documentation to make it worth my while to begin documenting the interfaces in schemas.
I’ve been bitten by Moose. Using real objects instead of raw hashes.

MSDN Blogs: Looking Forward: Microsoft Support for Secure Shell (SSH)

Wed, 03 Jun 2015 21:30:06 +0000

Fantastic news! MS Windows will support SSH both as client and server. This is superb! “… and there’re not exact days yet. However the PowerShell team will provide details in the near future on availability dates.” Source: MSDN Blogs

Metadata for beginners

Sat, 04 Jan 2014 15:39:54 +0000

Many people I’ve spoken to seem to think that they don’t have anything to hide, and as long as the government isn’t listening in on the actual phone conversations, then they’re fine with it. As you might guess, I’m not. This slide from 30th Chaos Communication Congress (30C3) hits the head on the nail.

UN votes to protect privacy in digital age - Hurray!

Sat, 04 Jan 2014 15:33:30 +0000

I honestly don’t understand why this wasn’t more publicized. It is great news! UN votes to protect privacy in digital age (from Associated Press)

Fantastic! Only real good news about this whole NSA scandal I’ve heard in a long time.

Director of national Intelligence James Clapper lies to US Congress - without consequences?

Sat, 04 Jan 2014 15:28:22 +0000

So, James Clapper, US Director of national Intelligence, lies to Congress. First he calls the lie the “least untruthful” answer he could publicly provide, and then cites a momentary memory failure. Seven congressmen take issue with James Clapper’s testimony, but Obama administration unlikely to turn against director.

See: Republicans demand consequences for ‘willful lie’ by intelligence chief | World news | theguardian.com

Let me recap: James Clapper, a retired lieutenant general in the United States Air Force (you’d think he knows right from wrong, truth from lie), lies under oath to US Congress and it is not likely to have any consequences for him.

Big Brother sees all but can't keep a secret?

Fri, 07 Jun 2013 19:03:15 +0000

Two news items from this week have me quite uneasy.

The NSA is basically listening in on every US citizen. For the sake of argument, let me assume that they get everything. So far I don’t think we’re quite there yet here in Denmark.

Data held by the Danish police has been hacked. We’re not sure exactly what the hackers have had access to, but we do know they’ve had at least read+write access to all driver’s license data and read access to the Schengen Information System, a large European database on police and judicial co-operation. They’ve been lurking around in there undetected for 6 months. Do you believe that is all they’ve had access to? In 2011 Pentagon Admitted 24,000 Files Were Hacked too.

Getting older?

Thu, 14 Jun 2012 20:39:12 +0000

The other day, I was cooking, and it was time to set the table.

Suddenly I found myself standing in the storage/utility room. And I had no idea why I was there. “Peter, you need to set the table! Get back on track!” - I told myself.

So I went back into the kitchen. Looked at the table: What was missing? Ah, drinks. OK, glasses, plastic cup for my daughter, pitcher of water - check. “Hey, I’d like a Coke”, so I opened the fridge. No Cokes. Should probably put some in the fridge for next time I want a Coke. I went to the utility room, and suddenly it hit me: That is what I was doing in the storage room! Getting Cokes for the fridge!

Watches - Oh - Watches

Thu, 26 Apr 2012 21:27:13 +0000

I love watches.

Being a techie, I really can’t accept a watch that isn’t accurate. The accuracy of a quartz-crystal based watch is the minimum. I wish I could get a Rolex, Omega or other really nice looking watch, but I just can’t accept the accuracy I’ll get from a watch like that. So all the beautiful Swiss watches are out for me. But there are alternatives:

Great Courses at Coursera

Fri, 20 Apr 2012 06:44:20 +0000

I’m currently taking a Cryptology course at Stanford University via Coursera. It came recommended by Bruce Schneier on Security: Free Cryptography Class, and I find it a great way to expand my knowledge. I really appreciate the level. Just enough for it to be challenging and stimulating, but also not too hard or too much work, so I can still fit it in with family and work.

And in addition, the courses are free!

SSH VPN with IP Masquerading (NAT)

Tue, 15 Nov 2011 22:36:12 +0000

I’ve written before about how to access SNMP agents (or other TCP or UDP services) in a network when you only have SSH access. Running a SSH VPN and then running IP Masquerading (NAT) in the remote end is the solution for me so far. Here is how it is done.

Seeing the Sun's Path - Android and iPhone apps

Mon, 14 Nov 2011 20:27:56 +0000

I’d like to recommend an Android App for seeing the Sun’s path in Augmented Reality (AR): Sun Surveyor. There is also Sun Seeker for iPhone/iOS, which I haven’t tried since I don’t have an iPhone.

We’re out looking for a house to buy, and for me getting the afternoon and evening sun on the terrace during summer is so incredibly important. This way, I don’t have to take the real-estate agent’s word for where the sun goes down in the summer and whether the trees will create shade on the terrace. I can check it myself. Über-cool!

Oh, god I hate PDF for on-screen viewing

Thu, 13 Oct 2011 20:36:09 +0000

Honestly, I don’t understand how somebody can prefer PDF to HTML for on-screen viewing. Really? That is possible? If you’re one of them, can you help me understand?

Increased surveillance is considered a positive by many? Yikes...

Sun, 18 Sep 2011 18:24:23 +0000

Here in Denmark, we’ve just had an election, and the previous government has been replaced.

A newspaper article [lang=“da”] looks back at what people liked and disliked about what the previous government did.

I have trouble believing, much less understanding, that 68% consider increased surveillance to have had a positive effect for Denmark, 16% believe the effect to be neutral and 16% believe it to be negative.

Wow. The people who believe that our society is better off when the government monitors us more out numbers people like me 4 to 1? Yikes. Has nobody read 1984 or seen Das Leben der Anderen? Doesn’t anybody remember DDR or the Soviet Union? Perhaps China will open source the great firewall too, so we can install it here!

NSA Open Sources an internally developed project

Thu, 08 Sep 2011 07:30:29 +0000

NSA proposes Accumulo NoSQL database to Apache, writes The H.

This is a big deal (at least in my book) because it demonstrates that the NSA does not believe in security by obscurity.

34 Cleverly Designed Inventions

Fri, 02 Sep 2011 06:51:57 +0000

Really cool list of 34 Cleverly Designed Inventions. I especially liked the USB connector, the stair case drawers, and the crawling lamp on the wall.

Thanks to the Userfocus Usability Newsletter for the link. The site also has lovely 32 Pictures To Help You Appreciate The Awesomeness Of Nature but I better let you go now :-).

How much do we trust posts on website forums?

Mon, 18 Jul 2011 18:47:41 +0000

A Danish Minister approves an ad-agency to pose as real users and stuff a forum with bogus posts to kick-start it. I’m appalled, surprised at my own ignorance and worried about the lack of credibility of even government-funded sites.

Natural Sort

Wed, 13 Jul 2011 06:52:08 +0000

Why doesn’t every programming language have “Natural Sorting” built in, out of the box? Natural sorting is the way humans sort, where number substrings are sorted numerically, everything else alphabetically:

Sorted “Asciibetically” (normal computer sort)	Sorted “Naturally” (what humans prefer)
foo1bar	foo1bar
foo10bar	foo2bar
foo2bar	foo10bar

Notice how 10 comes before 2 in asciibetical “normal computer sorting” ? Haven’t we all seen user interfaces that like that? Its just plain wrong. :-(

Dave Koelle’s Alphanum Algorithm sorts naturally, but instead of analyzing each array element O(log(N)) times, I present a modified Perl version that allows for Schwartzian transforms, yielding huge performance improvements.

Refresh your browser automatically during web development

Sun, 10 Jul 2011 12:08:43 +0000

Did you ever find that while editing files for the web (e.g. HTML, Javascript, Java/Flash/Ruby, whatever) that it would be cool to have your browser reflect any changes as soon as you hit Save in your IDE without having to Alt-Tab to the browser and hit refresh (Ctrl-R)? That way, you could stay entirely in your browser and just move your eyes to the browser as it refreshes automatically showing you the results of your newest changes.

Well, now you can! I’ve developed a pair of tools for that allow this when used in concert. Both are Open Source, of course.

Forwarding SNMP ports over SSH using socat

Tue, 05 Jul 2011 04:32:34 +0000

Here is an example of the problem we need to solve: We have SSH access to a network, but want to access an SNMP agent in that network from a local client. We use SNMP here in this example, but it could be any other protocol that uses UDP, such as DNS or TFTP.

We’ll forward the SNMP traffic in a TCP port like this, with “socat” doing the UDP-in-TCP tunneling:

Subversion: Setting the repository path for svn+ssh://server/repos

Sun, 20 Feb 2011 22:09:42 +0000

For some reason, it doesn’t seem to be possible to set up a path for your repository when using subversion as: svn+ssh://server/repos out of the box. So you end up having to specify svn+ssh://server/some/path/repos.

But it really isn’t that hard to do. Here is how I do it. Beware that you’re going to be making system-wide changes to how svnserve operates. The basic idea is to replace svnserve with our own version, that calls the original one with a -r parameter.

Classical Mechanics: Why does Power depend on frame of reference?

Tue, 15 Feb 2011 07:59:56 +0000

Imagine we’re in a rocket.

We have an imaginary engine, that provides a constant amount of thrust. How much power does such an engine provide? In essence the power depends linearly on the velocity:

\[ \begin{align*} P &= \frac{dW}{dt} \wedge W = \int F \cdot ds \Leftrightarrow \\[10 pt] P &= F \cdot \frac{ds}{dt} \Leftrightarrow \\[10 pt] P &= F \cdot v \end{align*} \]

And the velocity depends (by definition) on the frame of reference.

Deep Packet Inspection? Yup, bring it on!

Wed, 08 Apr 2009 00:00:03 +0000

Deep packet inspection could be useful to ISPs who oversell limited bandwidth to (too) many customers. With Deep Packet Inspection, my ISP could inspect the contents and details of the high-bandwith traffic going to and from my neighbor:

Our ISP could then determine most of it to be peer-2-peer traffic, and then limit exactly that peer-2-peer traffic so that my neighbor ( :-) ) doesn’t hog all the bandwidth that we all have to share. On the surface, that sounds like a great idea? Why should my neighbor ruin the internet experience for the rest of us? There’s a catch…

Documentation, Git and MediaWiki

Mon, 09 Feb 2009 00:00:51 +0000

I have a dream. I want to write structured documentation and source code together in my text editor and version control both together with git, just like the source code. But have it be searchable, viewable and ideally editable within MediaWiki. Is this possible?

Xen?

Wed, 03 Dec 2008 00:00:54 +0000

Now, do I want to run Xen? Hmm… I’m using it to host morch.com itself, and I think its great.

Compared to VMware workstation, which is my other favorite, I love that it is open source, and I love that it is detachable. That is, I can start it and don’t have any GUI artifacts hanging around. What I do with VMware workstation is start it under a VNC server, so I don’t have to worry about the GUI, but this isn’t about VMware but about Xen. [I’ve since learned that this isn’t true about VMware workstation - it has become detachable]