Search found 213 matches

by Demki
Wed Sep 28, 2016 7:11 am UTC
Forum: Mathematics
Topic: Vectors and Matrix Determinants
Replies: 3
Views: 2461

Re: Vectors and Matrix Determinants

In addition to cyanoshi's post, I think these 2 videos might help you, at least for the case of 3d vectors:
https://youtu.be/eu6i7WJeinw
https://youtu.be/BaM7OCEm3G0

These 2 videos are part of a series about linear algebra.
by Demki
Mon Sep 26, 2016 7:42 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1738:"Moon Shapes"
Replies: 66
Views: 15817

Re: 1738:"Moon Shapes"

In the same conversation, I also learned how to know whether the moon is waxing or waning: " La lune est menteuse ". The moon is a liar: when she looks like a "D", she's waxing ( c roissante); when she looks like a "C", she's waning ( d écroissante). I always went with...
by Demki
Mon Sep 26, 2016 8:05 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1738:"Moon Shapes"
Replies: 66
Views: 15817

1738:"Moon Shapes"

http://imgs.xkcd.com/comics/moon_shapes.png Title Text: "Whenever I see a picture of the moon where the points go more than halfway around, I assume it's being eclipsed by one of those Independence Day ships and interpret the rest of the image in light of that." What about moons with face...
by Demki
Sat Sep 24, 2016 10:00 am UTC
Forum: Mathematics
Topic: Dataset of linear systems
Replies: 21
Views: 4888

Re: Dataset of linear systems

kolobisbiko wrote:I want to find the properties of a matrix is there a "tool",software for that?
I don't think matlab can provide such information.....I want 10+ properties

What properties are you talking about?
by Demki
Mon Sep 12, 2016 5:13 am UTC
Forum: Mathematics
Topic: Goahead52's Math Posts
Replies: 148
Views: 18648

Re: Goahead52's Math Posts

Goahead, the thing is that all your posts are about number theory, so there's no real "searching for subject"
And we can search post text too.
by Demki
Fri Sep 09, 2016 9:14 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1731: "Wrong"
Replies: 42
Views: 11189

Re: 1731: "Wrong"

Also when black hat guy is wrong, it's because he wants to be wrong.
by Demki
Fri Sep 09, 2016 6:46 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1731: "Wrong"
Replies: 42
Views: 11189

Re: 1731: "Wrong"

Randall get out of my head. I meet too many people like him
by Demki
Wed Sep 07, 2016 3:13 am UTC
Forum: Mathematics
Topic: Pay to Win - a game theory problem
Replies: 21
Views: 6206

Re: Pay to Win - a game theory problem

Should they produce a binding contract such that they collect all the money [---] But that only works if they are allowed to do that, which I mistakenly assumed, as it wasn't written in the OP. Right, they can't do that, because neither knows how much "all the money" is. It could have bee...
by Demki
Tue Sep 06, 2016 4:03 pm UTC
Forum: Mathematics
Topic: Pay to Win - a game theory problem
Replies: 21
Views: 6206

Re: Pay to Win - a game theory problem

He could, but why would he? He doesn't know that A got more, so it's in his interest to defect. Say A got a money and B got b money. Should they produce a binding contract such that they collect all the money into one player's "bank", then they "cash out" a+b money and return ea...
by Demki
Tue Sep 06, 2016 12:33 pm UTC
Forum: Mathematics
Topic: Pay to Win - a game theory problem
Replies: 21
Views: 6206

Re: Pay to Win - a game theory problem

Well, if they can transfer before, then B could give A all the money he "got", then cooperate while A defects, giving A a+b while b still gets 0(and doesn't lose any because he only transfered the money that was allocated to him)
by Demki
Tue Sep 06, 2016 9:16 am UTC
Forum: Mathematics
Topic: Pay to Win - a game theory problem
Replies: 21
Views: 6206

Re: Pay to Win - a game theory problem

Ah, I think I have been assuming something not given, that they can transfer the money they were given BEFORE they choose to defect/cooperate. I guess I though too much about Liar Game(a psychological manga that has plenty of interesting games)
by Demki
Tue Sep 06, 2016 7:25 am UTC
Forum: Mathematics
Topic: Pay to Win - a game theory problem
Replies: 21
Views: 6206

Re: Pay to Win - a game theory problem

I'd say that in that case, the contract will be such that whatever money B gives to A, A returns that amount after A defects and B cooperates, since neither side can know the other's amount. Without a contract, A could always run off with the money. This way each side gains the money that was told t...
by Demki
Mon Sep 05, 2016 4:21 am UTC
Forum: Mathematics
Topic: Pay to Win - a game theory problem
Replies: 21
Views: 6206

Re: Pay to Win - a game theory problem

If they can talk freely, won't they just produce a contract so that one player, say A, would give all his money to B, then A cooperates and B defects, and they would share the money 50-50?
Sure B could lie about the money, but in the contract A can demand to see the piece of paper of B
by Demki
Fri Sep 02, 2016 9:02 pm UTC
Forum: Mathematics
Topic: How to Calculate Pi without a Calculator?
Replies: 66
Views: 14191

Re: How to Calculate Pi without a Calculator?

In the 50?*?<=2000, and such, you can use division and 1 or 2 multiplications. It's just (a+x)*x<=b, with x a digit. I am pretty sure that x=floor(b/a)-1 (with -1 mapped to 0) will always work, but I think that x=floor(b/a) might work sometimes, so unless someone can prove otherwise, that's 2 digit...
by Demki
Fri Sep 02, 2016 2:23 pm UTC
Forum: Mathematics
Topic: How to Calculate Pi without a Calculator?
Replies: 66
Views: 14191

Re: How to Calculate Pi without a Calculator?

In the 50?*?<=2000, and such, you can use division and 1 or 2 multiplications. It's just (a+x)*x<=b, with x a digit. I am pretty sure that x=floor(b/a)-1 (with -1 mapped to 0) will always work, but I think that x=floor(b/a) might work sometimes, so unless someone can prove otherwise, that's 2 digit...
by Demki
Thu Sep 01, 2016 5:03 pm UTC
Forum: Mathematics
Topic: How to Calculate Pi without a Calculator?
Replies: 66
Views: 14191

Re: How to Calculate Pi without a Calculator?

In the 50?*?<=2000, and such, you can use division and 1 or 2 multiplications. It's just (a+x)*x<=b, with x a digit. I am pretty sure that x=floor(b/a)-1 (with -1 mapped to 0) will always work, but I think that x=floor(b/a) might work sometimes, so unless someone can prove otherwise, that's 2 digits...
by Demki
Tue Aug 30, 2016 11:32 am UTC
Forum: Mathematics
Topic: Goahead52's Math Posts
Replies: 148
Views: 18648

Re: Goahead52's Math Posts

None that I know.
by Demki
Tue Aug 30, 2016 11:14 am UTC
Forum: Mathematics
Topic: Goahead52's Math Posts
Replies: 148
Views: 18648

Re: Goahead52's Math Posts

There are infinitely many multiples of 29 not divisible by primes less than 29. A subset of these multiples is {29^k | k∈N\{0} } and that subset is countably infinite.
by Demki
Wed Aug 24, 2016 9:51 pm UTC
Forum: Mathematics
Topic: Goahead52's Math Posts
Replies: 148
Views: 18648

Re: Goahead52's Math Posts

1+9+9^2+9^3+....+9^k= 1/2* ((3^k)-1)/2)((3^k+1)+1)/2) is true for all the k`s n=((3^k)-1))/2 Sum geometric sequence is easy. I skipped that part. I had just replaced n by its value so the equation become a pure identity. It that correct? No. It is actually 1+9+9^(2)+...+9^(k)=(1/2)((3^(k+1)-1)/2)((...
by Demki
Wed Aug 24, 2016 9:44 am UTC
Forum: Forum Games
Topic: Random bitstream! (000zerozero000000zero)
Replies: 1947
Views: 237077

Re: Random bitstream! (000zerozero000000zero)

Left nostril, I am left handed... 1
by Demki
Mon Aug 22, 2016 8:24 pm UTC
Forum: Mathematics
Topic: Goahead52's Math Posts
Replies: 148
Views: 18648

Re: Goahead52's Math Posts

Please stop triple-posting. You can edit your last post if it's still the most recent post in a thread. If an identity tells you nothing about a variable, then it doesn't tell you anything useful about that variable. How do you know that the same variable could be written differently using even ext...
by Demki
Mon Aug 22, 2016 1:32 pm UTC
Forum: Mathematics
Topic: Goahead52's Math Posts
Replies: 148
Views: 18648

Re: Factorization of odd semi prime is over!

Goahead52 wrote:knowing that n=pq is odd semiprime there is a solution to :
1. approximate phi(n)=2x
2. approximate y
As we know that 2x+y=a (with a known)

1. How do you approximate phi(n) without factoring n in the first place?
2. What is y and how do you approximate it?
3. What is a?
by Demki
Sun Aug 21, 2016 12:29 pm UTC
Forum: Logic Puzzles
Topic: Factorial puzzle
Replies: 6
Views: 3805

Re: Factorial puzzle

Here are your EFN on OEIS: https://oeis.org/A002618
Also n phi(n)=phi(n^(2))
by Demki
Thu Aug 18, 2016 1:09 pm UTC
Forum: Mathematics
Topic: 1 is Not Prime
Replies: 17
Views: 5900

Re: 1 is Not Prime

Note that while 1 isn't a prime, 0, i and 1/e are. Otherwise you can't factorize all numbers. 1/e prime? In what context? Non-integers of course! Otherwise, how would you factorize 1/2 or π? 1/2 is simply (1/e)^{a lot}*{a lot of primes}. Okay, so maybe something breaks if you have 1=2*(1/e)^{a lot}...
by Demki
Thu Aug 18, 2016 11:43 am UTC
Forum: Mathematics
Topic: 1 is Not Prime
Replies: 17
Views: 5900

Re: 1 is Not Prime

Flumble wrote:Note that while 1 isn't a prime, 0, i and 1/e are. Otherwise you can't factorize all numbers.

1/e prime? In what context?
by Demki
Mon Aug 15, 2016 9:03 pm UTC
Forum: Mathematics
Topic: Misunderstanding basic math concepts, help please?
Replies: 338
Views: 78786

Re: Misunderstanding basic math concepts, help please?

For Twistar's question: Agree.

Other than that, all I had to say was already pointed out, and in my previous post, and it seems that treatid decided to ignore the questions I raised in that post.
by Demki
Fri Aug 12, 2016 11:16 am UTC
Forum: Logic Puzzles
Topic: Sharing secret information publicly
Replies: 27
Views: 7037

Re: Sharing secret information publicly

If this was their solution I really think that is dumb one. A has 3 cards 1,6,7 He does not know what B has. He could write down 6 numbers : 1,2,3,5,6,7 by claiming my three cards are among those 6 cards which is true B has 3 cards : 2,3,5 He will then deduce that C holds the card 4 hence he will c...
by Demki
Tue Aug 02, 2016 7:03 pm UTC
Forum: Mathematics
Topic: Misunderstanding basic math concepts, help please?
Replies: 338
Views: 78786

Re: Misunderstanding basic math concepts, help please?

First: I have read your entire post, and most of your previous posts in this thread and the earlier threads. I am going to raise some questions and thoughts I had while reading it. Please try to answer them as clearly as you can. Also, the pertinent point is made that it really doesn't matter even i...
by Demki
Thu Jul 28, 2016 10:32 am UTC
Forum: Mathematics
Topic: Misunderstanding basic math concepts, help please?
Replies: 338
Views: 78786

Re: Misunderstanding basic math concepts, help please?

[i]{definition of 'know' here is problematic. While I don't think we can have absolute knowledge in a sense that I think axiomatic mathematics implies; I do think that we can create a complete description of the universe without needing to make any assumptions. How would you create a complete descr...
by Demki
Mon Jul 25, 2016 3:58 pm UTC
Forum: Mathematics
Topic: Goahead52's Math Posts
Replies: 148
Views: 18648

Re: Factorials

Food for thought: n!=A*B k!=B-A So n!=A(A+k!) Or A^(2)+k!A-n!=0 Solving for A: A=(-k!±sqrt(k! 2 +4n!)/2 If you want only positive A then limit it to only +. This means that k! 2 +4n! must be a perfect square, So maybe for given n you could try to find k such that k! 2 +4n! is a perfect square. This ...
by Demki
Wed Jul 20, 2016 10:46 am UTC
Forum: Mathematics
Topic: The liar paradox as a basis for kantian metaphysics
Replies: 11
Views: 3714

Re: The liar paradox as a basis for kantian metaphysics

What exactly do you mean by "x is true"? Is the empty set "true"?
by Demki
Sun Jun 05, 2016 12:07 am UTC
Forum: Mathematics
Topic: Misunderstanding basic math concepts, help please?
Replies: 338
Views: 78786

Re: Misunderstanding basic math concepts, help please?

Formal Logic Worksheet Since I started on this post, there has been further consensus for this, so I'll dive right in: 1. (~E V P) V U [prem] 2. (~E V P) ⊃ A [prem] 3. U ⊃ B [prem] 4. ~A [prem] ∴ B 5. ~(~E V P) V A [2. cond.] 6. A V ~(~E V P) [5, comm.] 7. ~A ⊃ ~(~E V P) [6, cond.] 8. ~(~E V P) ⊃ U...
by Demki
Tue May 03, 2016 4:59 pm UTC
Forum: Mathematics
Topic: Favorite math jokes
Replies: 1452
Views: 488582

Re: Favorite math jokes

Eebster the Great wrote:Surely it's a countably infinite line of mathematicians, not a line of countably infinite mathematicians. Unless each one has an unbounded number of cells or something.

They must be very dense.
by Demki
Sat Apr 02, 2016 8:41 pm UTC
Forum: Logic Puzzles
Topic: Drawing Two Bingo Balls
Replies: 3
Views: 3234

Re: Drawing Two Bingo Balls

The first solution that came to mind was this rather-inelegant one: <html><head><title>Brute Force</title> <script language="JavaScript"> function getanswer() { var a; var b; var count = 0; var sum = 0; for (a = 1; a <= 75; ++a) { for (b = 1; b <= 75; ++b) { if ...
by Demki
Wed Mar 30, 2016 5:21 pm UTC
Forum: Logic Puzzles
Topic: THIS IS A CHALLENGE FOR INTELLIGENT BRAINS
Replies: 4
Views: 4635

Re: THIS IS A CHALLENGE FOR INTELLIGENT BRAINS

Spoiler:
Harpo landed on his feet being in the Marx Brothers.
Poland
Her acting was far too "dog-in-the-manger" many people felt.
Germany
They met for a quick snog on the office landing on the first floor.
Iceland
A murder has taken place at Chaddington Grange.
Chad
by Demki
Thu Mar 17, 2016 10:56 am UTC
Forum: Mathematics
Topic: Convex problem set -- Who can solve this? I already solvedit
Replies: 5
Views: 2540

Re: Convex problem set -- Who can solve this? I already solv

Carlomario1990 wrote:Anyone can confirm what i do wrong in the diffferentiation part?
If i plot the graph, i get the right value, but with differentiatiton, i get the wrong value.

We can't check your work if you don't show it.
by Demki
Sat Jan 16, 2016 10:39 am UTC
Forum: Logic Puzzles
Topic: Escape the Frictionless Circle
Replies: 156
Views: 67060

Re: Escape the Frictionless Circle

Will this work? (assuming you're very strong, being in perfect health and all) 1. Pick up block, drop it on opposite side from where you picked it up from. 2. Climb over block. 3. Repeat 1 and 2. 4. Win. Would picking up the block and moving it through the vacuum to the other side cause your feet t...
by Demki
Sat Dec 26, 2015 5:12 pm UTC
Forum: Mathematics
Topic: difference between euler and leapfrog integrator
Replies: 5
Views: 3165

Re: difference between euler and leapfrog integrator

In euler integration you know the velocity as a function of position and time(v(t) as function of x(t) and t) What you do in euler intergration is choose some time interval, then assume at those intervals that velocity is constant. For each step the velocity is computed from the current time and cur...
by Demki
Mon Dec 21, 2015 4:07 am UTC
Forum: Language/Linguistics
Topic: Alternate Ways of Writing English
Replies: 9
Views: 6156

Re: Alternate Ways of Writing English

The biggest problem I have with CPG is the color coding. That's will lead to confusion among ~5% of the population, due to color vision deficiency. Instead you could use 3 colors distinct by hue, saturation and value, and have a pattern of them encode the information. Also ink is expensive, maybe ev...
by Demki
Thu Aug 20, 2015 3:59 pm UTC
Forum: Logic Puzzles
Topic: Who is What?
Replies: 21
Views: 4139

Re: Who is What?

I disagree that this is contradictory it is trivial David is the programmer born on the 31/01/1943 and Edward is the Engineer born on 01/08/1943 to the same mother and father Breaking down the facts individually 1. David and Edward are brothers [Irrelevant but creepy given the age gap] 2. {{J(D...

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