Passing under Shadow

Aug. 21st, 2017 09:13 pm
aris_tgd: Daenerys "Come not between the dragon and her wrath" (Daenerys dragon)
[personal profile] aris_tgd
Okay, so ECLIPSE. Wow. Let me just say: what everyone said is true, totality is not the same as 90% or even 99%. My friends and I were hanging out in the backyard watching the light dim and taking peeks at the disappearing crescent of the sun through filters, and watching the sliver vanish, and when that black disc totally covered the sun all of us kind of lost our shit.

It was super cool and in seven years when another eclipse hits this continent I encourage everyone on this continent to go check it out. It's worth it.

Of course, it's easy for me to say it's worth it, I only had to drive an hour north and then two hours back home again to see it. Ha! (I kid, it was only about an hour and a half on the way back, but damn was traffic awful on the way out of Salem for most of the day. The only reason my drive back was so reasonable is that I waited eight hours after the eclipse ended to start moving.)

I did not take any photos. I was busy staring at where the sun used to be and would be again and mildly freaking out.

Brian Aldiss (1925 - 2017)

Aug. 21st, 2017 11:14 am
james_davis_nicoll: (Default)
[personal profile] james_davis_nicoll
David Langford reports that Aldiss died in his sleep.

Books

Aug. 20th, 2017 02:12 pm
aris_tgd: Sarah Chambers, Cleric (Sarah Chambers cleric)
[personal profile] aris_tgd
The problem with Goodreads is that now I have two places to talk about books and I'm never sure if I posted here about finishing something. I really enjoyed the rest of The Inheritance Trilogy, the second book hit my buttons more than the third did but I liked both of them. I guess I found the relationships in the third one didn't quite hit my kinks the way I wanted them to, while the first and second ones did.

[Insert current gripe about superpowered woman/unpowered dude shipping and lack thereof. This series just had an absence rather than having it and "fixing" it, but I'm now on the lookout.]

Did I mention I read Roses in Amber and it was lovely? It was lovely. Queer and magical and full of awesome women and "I have to do this awkward thing because magic so we're both going to agree to live with it" which I love love love as a trope.

I also just finished The Dream Quest of Vellitt Boe which was terrific. I would normally like more dialogue but the author is doing a Lovecraft pastiche, so I'm grateful for the dialogue we did get! Sharp in all the right ways. I liked the ending but now I want more! (Not literally, but I'd like to see something set in this dreamworld fifty years out or so.)

I'm still in the middle of The Goblin Emperor, and maybe when I have a little more brain space I'll pick it up again.

40 Years Ago Today

Aug. 20th, 2017 04:56 pm
james_davis_nicoll: (Default)
[personal profile] james_davis_nicoll
The United States of America, then an independent nation, launched Voyager 2

I wonder if any of the people involved realized it would still be going two generations later?

Read more... )

Cookies successfully made

Aug. 20th, 2017 02:02 am
aris_tgd: Shadow ships, "We could tangle spiders in the webs you weave." (Tangle Spiders Shadows)
[personal profile] aris_tgd
I also successfully made from-scratch caramel and tempered chocolate.

So I feel pretty good about myself, even though I burned the first batch of cookies.

I don't have any pictures, but I plan on getting a few pics before they all get eaten.

trig approximations

Aug. 18th, 2017 07:33 am
mindstalk: (thoughtful)
[personal profile] mindstalk
One virtue of my math education was that it was fairly proof heavy; I feel I can demonstrate or prove most of what I know. I may have mentioned this not extending to sin(A+B), which I had to figure out later as an adult. It also didn't include detailed "how do we calculate this shit?" for stuff like trig, log, fractional exponents. Once you hit calculus the answer becomes "Taylor series or something better", but before then?

Feynman talks about it somewhat in Chapter 22 of his Lectures, which is a cool read; he goes from defining multiplication in terms of addition, to numerically suggesting Euler's law, and showing how to build up log tables along the way. It's a heady ride. But he doesn't talk about trig tables.

I've long had my own thoughts about those, and finally wrote some code to try out the calculations.

Basic idea is that given sin(a) = y/r, cos(a) = x/r, and the Pythagorean theorem, there are two right triangles for which we know the values precisely. The 45-45 is trivial, while the 30-60 one can be gotten from sin(60) = cos(30) = sin(30+30) = 2*sin(30)*cos(30). From there, you can apply the half-angle formula as often as you please, to get very small angles, at which point you'll notice that sin(x) ~= (approximately equal to) x for small x. Thus you can approximate an angle like 1 degree which you can't otherwise[1] get to, then use double and addition formulas to build back up to say 10 degrees or anything else.

The question in my mind always was, how good is that? And the code finally answers the question. Sticking to half-angle stuff is *very* accurate, matching the built-in function to 15 decimal places. Using a sin(1 degree) approximation and building up to sin(15 degrees) is accurate to 4 places; starting from 0.125 degrees instead is accurate to 6 places. I don't know how practically good that is; one part in a million sounds pretty good for pre-modern needs -- like, at that point can you make or measure anything that precisely? -- but Feynman says that Briggs in 1620 calculated log tables to 16 decimal places.

[ETA: hmm, I'd been assuming the built-in function, presumably based on power series, was the most accurate version, but maybe I should view it as deviating from the exact roots of the half-angle approach. Or both as having small errors from the 'true' value. Especially as Python's sin(30) returns 0.49999999999999994, not 0.5. Of course, both approaches are using floating point. sin(60) = sqrt(3)/2 to the last digit, but cos(30) is slightly different.]

[1] The two exact triangles basically give you pi/2 and pi/3, and those divided by 2 as much as you want. But you can't get to pi/5 exactly.
a/2 + b/3 = 1/5 #a and b integers
15a + 10b = 6
5(3a+2b) = 6
(note that 2a+3b=5 is totally solvable.)

Though I guess a more valid approach would be
c(1/2)^a + d/3*(1/2)^b = 1/5 #all variables integers
c*5*3*2^b + d*5*2^a = 3*2^(a+b)
5(c*3*2^b + d*2^a) = 3*2^(a+b)
which still isn't soluble.

Likewise for getting to pi/9 (20 degrees):
c(1/2)^a + d/3*(1/2)^b = 1/9
c*9*2^b + d*3*2^a = 2^(a+b)
3(c*3*2^b + d*2^a) = 2^(a+b)

Fig

Aug. 17th, 2017 05:48 pm
james_davis_nicoll: (Default)
[personal profile] james_davis_nicoll
Can maintain disdainful detachment even as another, unfamiliar, cat thoughtfully grooms Fig's hind paw.

Apropos of nothing

Aug. 16th, 2017 06:35 pm
aris_tgd: (shell beach)
[personal profile] aris_tgd
The random mer-people tail generator on springhole.net may be my favorite sketch prompt generator all day.

Woe is me

Aug. 15th, 2017 05:14 pm
james_davis_nicoll: (Default)
[personal profile] james_davis_nicoll
Just noticed the book I was going to read tonight won't be out until November, so I shouldn't review it any time soon.

A note for next year

Aug. 13th, 2017 10:16 pm
james_davis_nicoll: (Default)
[personal profile] james_davis_nicoll
As near as I can tell from these rules James Nicoll Reviews does not qualify as a fanzine (it provides too much of my income). It might be a semi-prozine (bad for me, because my numbers would not get me onto the long list) or Related (where I also don't think I would made it onto the long list).
james_davis_nicoll: (Default)
[personal profile] james_davis_nicoll
There was talk of having a bonfire in October. Was trying to come up with theme/justification because I am incapable of spontaneity. Thought it might be nice to tie it in somehow to the Year of Waterloo Region SF. Wondered "what SF book features bonfires as a central image?"

Perseids Watch 2017: Success!

Aug. 13th, 2017 02:15 pm
james_davis_nicoll: (Default)
[personal profile] james_davis_nicoll
Many meteors seen, among other things.

Read more... )

More stuff I've seen

Aug. 12th, 2017 11:38 pm
aris_tgd: A black and white spiral on a Go board (Pi spiral)
[personal profile] aris_tgd
Well, I finally watched the first season of American Gods. I generally enjoyed it! I wasn't looking for a lot, honestly--I didn't love the book, it was fine. The whole thing is so blisteringly ignorant of Native American existence much less traditions that it's infuriating if I think about it too much. (But I guess that's par for the course for Gaiman, not to mention other UK authors writing about American subjects, hem, Rowling.) So aside from that major glaring issue, it was fun. The characters are great. Orlando Jones as Anansi was fan-fucking-tastic, I loved Shadow, and Salim, and I love the dynamic between Laura and Mad Sweeney even though I don't much care for either of them individually. And of course watching Ian McShane have fun is always great.

I didn't realize until I got closer to the ending that the show only covers the first part of the book, but I suppose that's par for the course.

I've also watched the first couple episodes of Brooklyn Nine-Nine, which I am also enjoying. It's still got more awkward/embarrassment based humor than I like what with that dude who's interested in Rosa, but everything else is terrific. I knew I was going to love Captain Holt and I do, I love him so much, I will put up with just about anything in a show if it means getting to watch him for seasons and seasons on end.

Also, the new DuckTales is awesome. That is all.
james_davis_nicoll: (Default)
[personal profile] james_davis_nicoll
(I think?), and since the year is half over, what YA do you expect to be nominated next year?

Lady Bloodfight

Aug. 11th, 2017 01:57 am
aris_tgd: Sinclair and Sakai, "Time for a moment." (Time for a moment)
[personal profile] aris_tgd
Seriously, what?

It's the version of Bloodsport where everyone's a lady, sure. But it's actually more than that, it's got a slightly more developed plot and some great characters.

I mean, the fight scenes aren't terrific, there are a few nice touches but they're not brilliant, and some of the line readings were just awful. But you know what? This was FUN, and the plot was fun enough that it was definitely worth my time. I think it might be worth yours.

I mean... it's Bloodsport, only there's also some backstory about two women who were in the kumite five years ago and tied and there's some kind of grudge, which we figure out about over the course of the movie. They're told they have to train their own apprentices to fight in the next kumite, and they each find out some more of that tragic backstory. It's cool, and there's neat stuff happening!

Look, it's like an hour and forty five minutes of ladies punching each other with some definite femslash feels going on there. I want everyone in the movie to make out with each other, even the scary Russian lady. It's on Netflix, check it out.

I kind of headcanon Jane as the daughter of Jean Claude Van Damme's character from Bloodsport and that reporter.

Fig and Ibid

Aug. 9th, 2017 08:33 pm
james_davis_nicoll: (Default)
[personal profile] james_davis_nicoll
Fig is content to wander around the large room he and his brother are in. Ibid is still hiding at the back of the top shelf (1) but came out for about an hour of combing. And attempted earbud eating.

Oddly, they don't seem to be eating their wet food (I did see both eat dry). I think it may be as simple as they are getting it in one bowl and don't know whose bowl it is supposed to be.

1: His host stacked bins so the cats can jump down without hurting themselves.
james_davis_nicoll: (Default)
[personal profile] james_davis_nicoll
Do reformed minions, mooks and goons have support groups?

Profile

tangaroa

August 2017

S M T W T F S
  12345
6789101112
13141516171819
20212223242526
2728293031  

Page Summary

Style Credit

Expand Cut Tags

No cut tags
Page generated Aug. 22nd, 2017 09:21 am
Powered by Dreamwidth Studios