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Make Truncation be Rounding

When I see a number like "183" the first thing I see is a "1". If I'm looking very quickly, perhaps scanning a column of numbers, that might be all I see, and I'll approximate this number as "100" when "200" would be closer. Yes, truncation isn't the same thing as rounding, but wouldn't things be a lot easier if it were? Let's make it be that way.

To interpret a number today, you multiply each column by the size it represents and add them up:
number100s10s1ssum
1001001*100 + 0*10 + 0*1
1201201*100 + 2*10 + 0*1
1211211*100 + 2*10 + 1*1
1291291*100 + 2*10 + 9*1
1251251*100 + 2*10 + 5*1

With this new system, we still do this, but in each column our available options range from -5 to 4 instead of 0 to 9.

number100s10s1ssum
1001001*100 + 0*10 + 0*1
1201201*100 + 2*10 + 0*1
1211211*100 + 2*10 + 1*1
12913-11*100 + 3*10 + -1*1
12513-51*100 + 3*10 + -5*1

Here are a few more examples:

old notationnew notation
00
44
71-3
5791-4-2-1
432432
1999200-1

And here's a program to calculate these:

def to_new_notation(x):
  digits = []
  carry = False
  for digit in reversed([
        int(x) for x in str(x)]):
    if carry:
      digit += 1
      carry = False

    if digit >= 5:
      digit -= 10
      carry = True

    digits.append(digit)

  if carry:
    digits.append(1)

  digits.reverse()
  return digits

Update 2016-05-25: Truncation isn't actually rounding in this system unless you allow both 5 and -5 as digits. Thanks to Marius for pointing this out.

full post...

Velcro Blackout Curtains

When Lily was about six months old I posted about blocking out the light in our room so that she would keep a later schedule. In that post I talked about taping up tinfoil, but the problem with this is that there's no way to let in natural light if you want to. This isn't a problem for me: I like to have the bedroom just be a sleeping space, but Julia likes to use the bedroom to work, read, and hang out, and having only artificial light isn't very nice. So we needed to switch to a removable system.

The tricky part with this is that if you really want it to work you need the kid not to be able to tell that it's getting light outside at all, with day and night being equally dark. So it's not enough to just hang regular blackout curtains, because they'll still get their day/night visual cues and wake up earlier and earlier as the sun comes up earlier. What we found worked well was to have one blackout curtain attached to the inside of the window frame with velcro, and then another one hanging over the front.

For the first curtain, run hook-side velcro around the inside of the frame, attaching it with small screws:

more...

Two Distribution Graphs

At last year's big EA conference, Tyler Alterman gave a talk on "succeeding at EA Global" (video). He opened with an argument that people should be open to changing their minds about what they should be doing. He described two worlds, a "Gaussiana" where outcomes are approximately Gaussian, and a "Paretonia" where they follow a Pareto distribution. Citing Toby Ord's arguments in The Moral Imperative Towards Cost-Effectiveness (pdf) that a Pareto distribution is closer to what we see [1], and noting that in a Pareto distribution the top outcomes are much much greater than average outcomes, he argued people should be giving a lot of thought to whether they could be working on something higher impact.

He showed two graphs to illustrate this:

These two graphs are how people commonly visualize these two distributions, but they're not equivalent graphs. more...

When Are Dance Weekends?

It feels like some weekends there's a lot going on in terms of dance weekends and festivals, while other weekends there's not so much. Since I maintain a list of these events, though, I could check:

more...

HTTPS Support

This site is now available over HTTPS, with certificates from Let's Encrypt: https://www.jefftk.com.

The certificates only last for three months, and I don't have automated renewal set up, so the https site might go down briefly every so often for the cert being out-of-date if I forget to renew. Once I sort this out I can redirect the http site to https, but I'm wary of doing it before then.

The letsencrypt-auto command I'm using is: more...

Adding a Bathroom

Shortly after buying our house, we decided to split an awkwardly shaped 3rd-floor bedroom into a smaller bedroom and a bathroom:

current proposed

It took a little longer than we expected, and there were some surprises along the way, but it's done now!


(This image is rotated from the previous ones, sorry!)


(interactive 3D version)

In general, the plan was that I would do as much of the work as possible, by myself or with friends. In Massachusetts I can't do electrical or plumbing work, so I was going to hire people to do these, but there's a lot of other work that goes into making a bathroom! That division is mostly what we ended up with, but with the working time being my free weekends it ended up taking a lot longer than we initially expected.

Here's a rough timeline: more...

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