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Author Topic: Random Stuff Part IV  (Read 139531 times)

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GendoIkari

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Re: Random Stuff Part IV
« Reply #475 on: June 24, 2019, 02:41:21 pm »
0

Try calculating sqrt(4)-2 in Windows calculator.
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silverspawn

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Re: Random Stuff Part IV
« Reply #476 on: June 24, 2019, 02:58:30 pm »
0

Java probably can do that, you're just using the wrong datatype if you need such precision.
well yeah, I didn't expect it to be impossible. But using a non-primitive datatype is way too much effort for this case

Try calculating sqrt(4)-2 in Windows calculator.

-8,1648465955514287168521180122928e-39

I've actually started to use python instead of the windows calculator, since it's about as easy to start and shows me past calculations. And python gives sqrt(4) - 2 = 0.0

Watno

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Re: Random Stuff Part IV
« Reply #477 on: June 24, 2019, 03:01:19 pm »
0

 I usually use the adress bar of my browser for calculations. I aleady have that open.

Also, are there different Windows calculators? because mine gives me 0.
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silverspawn

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Re: Random Stuff Part IV
« Reply #478 on: June 24, 2019, 03:01:52 pm »
0



Man, I'd have found it fairly disturbing if e^pi - pi = 20 would actually be true.

I usually use the adress bar of my browser for calculations. I aleady have that open.

I always feel bad about wasting power when I do that.

Titandrake

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Re: Random Stuff Part IV
« Reply #479 on: June 24, 2019, 03:06:04 pm »
+1

Turns out the Windows calculator issue wasn't because of floating point error, it was because the calculator internally represents all numbers as the quotient of really big integers.

http://daviddeley.com/profdeley/math/windows_calculator/index.htm

Newer versions likely did it in a different way. Standard floating point numbers are accurate enough that sqrt(4) just works out to 2.0 which can be represented exactly.
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Re: Random Stuff Part IV
« Reply #480 on: June 24, 2019, 04:54:22 pm »
+1

Man, I'd have found it fairly disturbing if e^pi - pi = 20 would actually be true.

I don't think it would be any more disturbing than e ^ (pi * i) = -1 .
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silverspawn

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Re: Random Stuff Part IV
« Reply #481 on: June 24, 2019, 05:05:32 pm »
0

Man, I'd have found it fairly disturbing if e^pi - pi = 20 would actually be true.

I don't think it would be any more disturbing than e ^ (pi * i) = -1 .

It might be hindsight bias, but I think that's a lot less disturbing. These are all very special pieces and the result has norm 1.

ConMan

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Re: Random Stuff Part IV
« Reply #482 on: June 24, 2019, 07:27:02 pm »
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Ugh, why must precision errors follow me even here? I just had some fun dealing with the fact that the same equation, written in two different languages, operating only on integers, was getting results that differed by 1. I had to implement a clunky version of big integer arithmetic in a language not designed to handle it, to deal with the issue.
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blueblimp

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Re: Random Stuff Part IV
« Reply #483 on: June 25, 2019, 08:23:44 am »
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Turns out the Windows calculator issue wasn't because of floating point error, it was because the calculator internally represents all numbers as the quotient of really big integers.

http://daviddeley.com/profdeley/math/windows_calculator/index.htm

That's an interesting page, although my takeaway is different: the problem is that the calculator computes square root using multiple operations and the intermediate values can't be exactly represented. The reason they can't be exactly represented is that they're irrational (actually maybe even transcendental), so floating-point should have the same problem if you calculate sqrt that way. I went to try it in Python, and, funnily enough, math.exp(0.5 * math.log(4)) produces exactly 2. I think this is just luck though, because math.exp(0.5 * math.log(9)) does not produce exactly 3. (The "luck" being that the inexactness in the log and exp happen to cancel each other out.)

A more typical sqrt implementation is guaranteed to produce the exact result if it can be represented: https://stackoverflow.com/a/22260439.
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silverspawn

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Re: Random Stuff Part IV
« Reply #484 on: July 06, 2019, 11:02:04 am »
+4

only in dominion do you buy potions that produce potion that buys alchemists

Kuildeous

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Re: Random Stuff Part IV
« Reply #485 on: July 22, 2019, 12:01:41 am »
+8

So I was at a convention this weekend, and my wife and I checked out Alien Artifacts because I confused it with Alien Frontiers. As I stared dejectedly at the rulebook and my wife glanced disinterestedly at the many decks of cards, we weren't really much in the mood to crack this game. My wife looked over at the next table and saw a couple of guys fussing with the instruction sheet for Dice Forge in a similar manner. She suggested that I go teach them Dice Forge. So I invited myself and my wife to join these guys so I could teach them how to play.

We chatted a bit, and Dominion came up. Talked some more, including Isotropic. I asked if he was on the forums, and he said his name was DSell. So I told him my name, and we had a lovely bonding moment at our first in-person meet. We played a few more games together, and I also got to teach him Sagrada since his SO is colorblind and will never play it with DSell. Good times. Such a nice guy.
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Dsell

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Re: Random Stuff Part IV
« Reply #486 on: July 22, 2019, 12:59:07 am »
+6

I asked if he was on the forums, and he said his name was DSell.

I had so so so so so much fun this weekend. This was one of my first few cons, and meeting/playing games with Kuildeous and his wife was one of the very best highlights!!
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Re: Random Stuff Part IV
« Reply #487 on: July 26, 2019, 10:35:11 am »
0

Were you guys at WBC?  I just came back from there.  Won the Dominion tournament for the second time.  151 players!
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Kuildeous

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Re: Random Stuff Part IV
« Reply #488 on: July 26, 2019, 06:50:14 pm »
+1

Were you guys at WBC?  I just came back from there.  Won the Dominion tournament for the second time.  151 players!
No, we crossed our paths at KantCon, which was originally named such by the organizers as they can't go to Gen Con. It's grown considerably since then and obviously doesn't base its schedule on Gen Con's weekend.

Might see each other again at the Midwest Game Fest in November.
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silverspawn

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Re: Random Stuff Part IV
« Reply #489 on: August 05, 2019, 09:25:39 am »
0

I just looked at Qvist's card lists of 2018.

Damn people are wrong about so many things.

But how come I'm not beating everyone if they're all so wrong? :(

Awaclus

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Re: Random Stuff Part IV
« Reply #490 on: August 05, 2019, 09:53:26 am »
+2

I just looked at Qvist's card lists of 2018.

Damn people are wrong about so many things.

But how come I'm not beating everyone if they're all so wrong? :(

You should go to the threads and post the things that people are wrong about so that we can laugh at your opinions.
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silverspawn

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Re: Random Stuff Part IV
« Reply #491 on: August 05, 2019, 10:50:25 am »
+1

Next time. I don't want to necro them.

But I was right about lookout, i.e. right in 100% of all cases where I expressed controversial opinions. Extrapolating that, I'm probably right about 100% today.

popsofctown

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Re: Random Stuff Part IV
« Reply #492 on: August 05, 2019, 04:10:57 pm »
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My profile says I have 2,728 respect.

That can't be right, can it? Is the forum bugged?  It'd be like 2 respect per post I think and I posted a bunch before respect was added.
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Awaclus

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Re: Random Stuff Part IV
« Reply #493 on: August 05, 2019, 04:38:32 pm »
0

My profile says I have 2,728 respect.

That can't be right, can it? Is the forum bugged?  It'd be like 2 respect per post I think and I posted a bunch before respect was added.

You have 5308 posts.
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popsofctown

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Re: Random Stuff Part IV
« Reply #494 on: August 06, 2019, 12:08:50 pm »
+1

That's 0.5 respect per post, not 2 respect per post.

I'm literally too dumb to breath.
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Kuildeous

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Re: Random Stuff Part IV
« Reply #495 on: August 06, 2019, 02:58:33 pm »
+2

Is there a legitimate reason for elementary school to teach division using the obelus symbol (÷) rather than the fractional notation? Or even the forward slash (/) if you must type expressions on a single line?

I see some of those math puzzles on Facebook, and it bugs me because there's an obelus, and nobody who maths for a living uses the obelus. 

And many of those Facebook arguments could be quelled with a properly notated fraction, but then that doesn't generate traffic.
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Awaclus

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Re: Random Stuff Part IV
« Reply #496 on: August 06, 2019, 03:06:00 pm »
0

Is there a legitimate reason for elementary school to teach division using the obelus symbol (÷) rather than the fractional notation? Or even the forward slash (/) if you must type expressions on a single line?

I see some of those math puzzles on Facebook, and it bugs me because there's an obelus, and nobody who maths for a living uses the obelus. 

And many of those Facebook arguments could be quelled with a properly notated fraction, but then that doesn't generate traffic.

We were taught : for division, which is at least a symbol that is used IRL.
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popsofctown

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Re: Random Stuff Part IV
« Reply #497 on: August 06, 2019, 03:46:20 pm »
0

Is there a legitimate reason for elementary school to teach division using the obelus symbol (÷) rather than the fractional notation? Or even the forward slash (/) if you must type expressions on a single line?

I see some of those math puzzles on Facebook, and it bugs me because there's an obelus, and nobody who maths for a living uses the obelus. 

And many of those Facebook arguments could be quelled with a properly notated fraction, but then that doesn't generate traffic.
Children like pictures.  An obelus is a picture of a fraction, you imagine the top dot being replaced with a numerator number, and the bottom dot being replaced with a denominator number.  The "/" is a metaphor for that as well, of course, but it's not quite as clear, it has that twist of perspective to it. It's particularly tricky to imagine the left number is somehow above the right number when you're roughly 8.
It is very useful for expressing the idea that division can be treated both like a function/operand where the operator and the divisor mutate the the first term to become a different, lesser tem, but it can also be treated like a representation, where the numerator and denominator are peacefully existing on the appropriate sides of the dividing bar, each playing their role in representing some value, and both values are part of how that value is represented.  And use of the obelus emphasizes that these are both actually the same thing.  This smooths to transition to algebra.


Your question comes off like "Is there a reason why my neighbor's bratty kid gets tiny little wheels on the rear wheel of his bike so that he can never fall off, doesn't he know Lance Armstrong would NEVER use those?!!?"


I agree using fractional notation is ideal, there's not always room for it, though, and then the obelus is much better than using a slash.  Late when you become a professional and need fewer penstrokes and better use of visual space the slash becomes better.
« Last Edit: August 06, 2019, 03:51:32 pm by popsofctown »
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blueblimp

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Re: Random Stuff Part IV
« Reply #498 on: August 06, 2019, 04:25:05 pm »
+3

Your question comes off like "Is there a reason why my neighbor's bratty kid gets tiny little wheels on the rear wheel of his bike so that he can never fall off, doesn't he know Lance Armstrong would NEVER use those?!!?"
The extra hardcore way to write division is with multiplicative inverse. ab-1 instead of a/b.
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Kuildeous

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Re: Random Stuff Part IV
« Reply #499 on: August 06, 2019, 04:30:11 pm »
+2

Children like pictures.  An obelus is a picture of a fraction, you imagine the top dot being replaced with a numerator number, and the bottom dot being replaced with a denominator number.  The "/" is a metaphor for that as well, of course, but it's not quite as clear, it has that twist of perspective to it. It's particularly tricky to imagine the left number is somehow above the right number when you're roughly 8.

Surely it's even trickier to imagine the left number being above the right number when writing 12÷4. I'm not sure how that's easier than a slash at all. The obelus acts nothing like training wheels. If anything, it's something to learn while young and then unlearn when kids decide to progress beyond 5th-grade math. This seems highly inefficient to me.
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