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Dennis Gorelik
13 April 2019 @ 01:35 pm
It gets better:
What you can do is to use methods where you [have] do not need any calibration whatsoever and you can still can get pretty good results.
So here on the bottom at the top is the truth image, and this is simulated data, as we are increasing the amount of amplitude error and you can see here ... it's hard to see ... but it breaks down once you add too much gain here. But if we use just closure quantities - we are invariant to that.
So that really, actually, been a really huge step for the project, because we had such bad gains.

"Вот тут мне карта и поперла".

And you can notice like at the bottom we get really terrible reconstruction, just cause if it fits the data very well, because you know it maybe wants to smooth out the flux as much as possible and we don't select things like that in the true data.

I posted a comment below that video:
19:39 "Calibration Free Imaging"
Does it mean that you were using measurements tools (telescopes) without prior calibration?
but it got deleted... twice.

Originally posted at: https://dennisgorelik.dreamwidth.org/170455.html
Dennis Gorelik
13 April 2019 @ 12:57 pm
"So we do calibration at the same time as imaging"

Calibration in measurement technology and metrology is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy.

The only image of "known accuracy" that these scientists had during black hole imaging -- was a theoretical image of how that black hole should look like.
But it is invalid to use that theoretical image as a self-proof that this theoretical image is correct.

So this team of "black hole photographers":
1) Took an extremely sparse signals from their several telescopes.
2) "Calibrated" their "signal interpretation" algorithm based on the theoretical black hole image (that they wanted to see).
3) Made "calibrated" "signal interpretation" algorithm to interpret sparse signals.
4) Not surprisingly, their "signal interpretation" algorithm produced theoretical black hole image that these "photographers" wanted to see.

What these "black hole photographers" did is NOT science, but scientific scam.

That explains why these "photographers" instead of photographing Sagittarius A (that is 26 thousand light years away) chose to photograph Messier 87 (that is 53 million light years away -- 2000 times further!)

At shorter distances there is not enough room for creative "calibration" of sparse signals.

See also:
Extracting a black hole image from "sparse telescope matrix"

Originally posted at: https://dennisgorelik.dreamwidth.org/170075.html
Dennis Gorelik
10 April 2019 @ 11:16 pm
Tel Aviv's liberal journalist Iris Zaki interviews conservative settlers in West Bank:

Originally posted at: https://dennisgorelik.dreamwidth.org/169817.html
Dennis Gorelik
Katie Bouman is a human face of the team that produced a black hole image that hit the news today:

2 years ago Katie delivered a TED talk about that image extraction efforts:

It is an interesting presentation, but I do NOT understand Katie's explanation about how they were going to minimize the bias [to "see" already predicted black hole visualization] while creatively interpreting inputs from sparsely placed telescopes around the earth.

Do you understand Katie's explanation?

Katie Bouman resume

How to Understand the Image of a Black Hole

Originally posted at: https://dennisgorelik.dreamwidth.org/169701.html
Dennis Gorelik
28 years old actress thinks that she knows better than billionaires how to manage the country:

Jennifer is a smart, energetic and successful young woman, so in this video she correctly describes how political system works (in particular, that big money have huge influence on the political decisions in the US).

But due to her youth and inexperience Jennifer failed to understand the root cause of why billionaires have such strong influence on the politics. It is not just because billionaires can use their money to influence politics. The political system is, actually, working much better when people who are able to earn and accumulate wealth have stronger influence over the politics.
Both billionaires and [relatively] poor people majority benefit from billionaires having stronger influence over the US politics.

Consider Venezuela where billionaires failed to control the government power and allowed socialism to take over. The whole Venezuelan population is suffering now as a result.

I will take "average billionaire" opinion over "average voter" opinion any day.

Originally posted at: https://dennisgorelik.dreamwidth.org/169319.html
Dennis Gorelik
31 March 2019 @ 02:52 pm
HN discusses how hard it is to deal with negative feedback as a Free Software Maintainer

These maintainers' complaints seem strange to me.

I am running a free job posting website.
Every day I receive about a hundred emails with various requests, questions and complaints (from recruiters, job seekers and operators of other job boards).

Some of these emails are negative or even outright rude.
But that negativity does not really bother me. I evaluate level of "Negativity" in the email to understand the nature of the request better (Is the request realistic? Is the request fair? Could our team realistically prevent that negativity in the first place?)

Requests like: “How dare you not (use your free time to) fix this ultra high priority bug that is affecting me?” -- I do not even consider negative. In fact, that is a positive comment to me, because it may indicate an opportunity (to make our job board better or to even add another revenue stream).

The complainer in such case already did some of the work for our job board: identified potential problem, described how to reproduce it, defined the use case explaining why fixing that problem is important.

If that is not helpful feedback, then what kind of feedback is more useful?

Originally posted at: https://dennisgorelik.dreamwidth.org/169154.html
Dennis Gorelik
25 March 2019 @ 02:32 am
From 11 years of maintaining my own codebase I learned that reusing fields is a bad idea that leads to poor code maintainability.
If unrelated methods use the same fields, then graph of field references start looking like a maze that is very hard to understand.
If "UserId" field is called by 19 methods from at least 2 distinct logical groups, then it takes long time to find out if we still need to load UserId from database record in JobAlertRequest().
If count of UserId references was much lower, then such review would take much less time.

Reusing fields (and local variables) is, generally, bad for maintenance.
But reusing methods is, generally, good for maintenance: if we fix bugs in a reused method - all places that use functionality are getting fixed.

Originally posted at: https://dennisgorelik.dreamwidth.org/168845.html
Dennis Gorelik
08 March 2019 @ 07:53 pm
Birth date: 2019-03-06 (2 days old).
Weight: 2590 grams.
Height: 49.5 cm.

Baby boy (choosing name)

Originally posted at: https://dennisgorelik.dreamwidth.org/168373.html
Tags: , ,
Dennis Gorelik
06 March 2019 @ 12:11 pm
This photo was made 3:40 am EST today (2019-03-06) -- 1 hour 35 minutes before baby delivery.


Originally posted at: https://dennisgorelik.dreamwidth.org/167962.html