
Cosines and correlation (2010) - ColinWright
http://www.johndcook.com/blog/2010/06/17/covariance-and-law-of-cosines/
======
nabla9
In the same fashion, look up the formula for the standard deviation for
discrete random variable. Then look at the formula for euclidean distance.

~~~
ColinWright
I'm not sure what you're saying here, because that seems to me to be _exactly_
what the article is saying in the first page or so.

~~~
nabla9
I was trying to be more explicit and look inside sd.

I think it's helpful if you can make the random variable/signal/data ~ vector,
values/dadatpoints ~ coordinates connection as explicit as possible.

~~~
ColinWright
It's not too late - there might be value in going back and editing your
original comment to flesh out your points. As it stands it's not clear what
you're adding. If you do that, then we can delete these discussion comments
and leave something useful, with less noise.

 _Edit: now it is too late._

~~~
nabla9
[https://news.ycombinator.com/user?id=ColinWright](https://news.ycombinator.com/user?id=ColinWright)

>trying real hard to stop finding and marking duplicates.

I sympathize with the crusade, but maybe repetition and saying same thing
differently is not entirely without value.

I'm not saying you are wrong, but sometimes different angle to the same thing
helps people to learn.

~~~
ColinWright
When exactly the same item is on the "Newest" page twice and the front page as
well, there's something wrong. But I've stopped, it's not going to get better,
it's not going to be fixed, and basically, I've stopped trying to help.

That's one of the larger scale things about the internet that bothers me - it
rewards not caring, and trains you not to care. With the various communities
I've engaged with, when people care they are useful and constructive. When
people stop caring, they go downhill and become cesspools. It bothers me when
there's a negative comment and people say "You shouldn't care so much."

Well, largely now I've stopped caring about HN. I occasionally submit
something, but now when I do so, I just leave. I sometimes read comments and
will sometimes interact - like now - but mostly I start typing a reply or
response, stop and think "why should I care", and then delete it and leave.

I've been trained not to care.

====================================

Edit:

Example of the duplications:

* [https://news.ycombinator.com/item?id=10499256](https://news.ycombinator.com/item?id=10499256)

* [https://news.ycombinator.com/item?id=10499250](https://news.ycombinator.com/item?id=10499250)

* [https://news.ycombinator.com/item?id=10499273](https://news.ycombinator.com/item?id=10499273)

It used to be that when I noticed these I'd put a pointer in one to the other
so discussions didn't get split. Now I just don't care.

~~~
dang
Those aren't dupes by HN's definition because none of them has had significant
attention yet. Please see the FAQ:
[https://news.ycombinator.com/newsfaq.html](https://news.ycombinator.com/newsfaq.html).

Why do we do it this way? Because good stories frequently get overlooked, and
not allowing any reposts at all would doom those to obscurity, which would be
bad for HN. Just as in startup investing the most important thing is not to
miss a good company, on HN the most important thing is not to miss a good
story.

Btw, posts that use identical URLs are rejected for 8 hours, to avoid
stampedes. But not all of those posts used identical URLs.

~~~
ColinWright
Yes, I've been following with interest the evolution of the treatment of items
that some might regard as duplicates. I agree that there are items that
deserve a second chance, because the HN firehose pretty much guarantees that
good items (by some definition) will be missed, and sink without trace.
Leniency in the definition of "duplicate" is one way to go, as is the
encouragement of reposts of items you think are good for HN and deserve a
second chance.

But having multiple copies of the same story - HN defined duplicate or not -
means that there is less space for other new stories. I realise I'm not saying
anything you don't already know, and I'm not offering a different strategy,
I'm just saying that I see you're doing things (whether I agree with them is
irrelevant) and so my previous strategy of cross-linking duplicates (by my
definition) has been discontinued.

You'll notice, by the way, that those specific three were submitted within
minutes of each other. It all adds up to my conclusion that, in effect, I've
stopped bothering. I recognise that you are working on this, and I appreciate
your efforts.

~~~
nkurz
You've obviously thought about this lots. Is there a better way that you
envision? My instinct is that it's best solved with more explicit curation of
submissions, but I can't yet picture a full working system.

~~~
ColinWright
I think the primary unit should be "the story". I think that submissions of
the same story should come under an umbrella meta-submission. This will allow
different points of view, without splitting the discussion.

New submissions of the same story can be identified as "identical" or
"related", and either dropped or merged. All this can be curated by people who
simply happen to notice the duplication, and most users need not do anything.

The addition of a "meta-submission" might be too much of a step for the
software, though. With some thought it should be possible to integrate the
idea into the existing structure, but I know nothing about the internals, so I
can't say for sure.

~~~
dang
That's actually pretty close to something we've been working on. I don't know
when it will be ready though.

Catching not only identical stories but also related ones is important,
because often the same story appears in a dozen or even several dozen guises.

------
gaius
Now I wish there was a cos button on my HP-12C!

~~~
nkurz
In the unlikely case that your life really would be improved by having trig
functions available on your HP-12C:
[http://www.hpcc.org/datafile/hp12/12c_TrigonometryFunctions....](http://www.hpcc.org/datafile/hp12/12c_TrigonometryFunctions.pdf)

~~~
gaius
Amazing!

But for trig (and matrices, root finding and numerical integration) I now have
a beautiful DM-15L from swissmicros.com :-)

