## Search found 29 matches

Sat May 18, 2013 2:28 pm UTC
Topic: 1213: "Combination Vision Test"
Replies: 159
Views: 65871

### Re: 1213: "Combination Vision"

That's obviously the Death Star.
Tue Jan 01, 2013 4:13 pm UTC
Forum: Mathematics
Topic: Powers of 2 and 3
Replies: 7
Views: 1919

### Re: Powers of 2 and 3

If you write 3 n in binary, the next highest power of two is pretty easy to find (it's a one followed by a bunch of zeroes that's one bit longer than what you're subtracting from it). Subtracting will essentially give you the twos complement representation of -3 n : -3 0 = 1111111111111111 (0) -3 1 ...
Tue Jan 01, 2013 4:40 am UTC
Forum: Mathematics
Topic: Powers of 2 and 3
Replies: 7
Views: 1919

### Re: Powers of 2 and 3

It is pretty easy to show that a^n-b^n increases monotonically with n which implies this is true for a=3 and b=2. The original post is about 2 n and 3 p . The powers (n and p) don't have to be the same. For instance 2 2 is right next to 3 1 even though the powers are different. Perhaps at some rand...
Tue Jan 01, 2013 4:31 am UTC
Forum: Mathematics
Topic: Boy Girl Problem
Replies: 25
Views: 3658

### Re: Boy Girl Problem

...let's call the boy we know about 'B'... Alternatively, let's arbitrarily label the boy we know... We know that the two children contain one boy or two boys. If there are two boys, the information we're given sure isn't pointing out "the boy we know" at all. You haven't eliminated the p...
Tue Dec 11, 2012 5:45 am UTC
Forum: Mathematics
Topic: Transliterating numbers into other bases
Replies: 13
Views: 2222

### Re: Transliterating numbers into other bases

One problem is, if you're transliterating into a smaller base, what are digits that don't appear in the smaller base supposed to mean? Ignoring that, an easy algorithm to transliterate without fully encoding or decoding is the following: def transliterate(starting, ending, n) ending_power = 1 result...
Sun Dec 02, 2012 11:43 pm UTC
Forum: Mathematics
Topic: "Fuzzy" arithmetic?
Replies: 3
Views: 1372

### Re: "Fuzzy" arithmetic?

If you really want to get into it, you can combine the probability distributions of the original values properly to get the probability distribution for the result.
Sun Dec 02, 2012 11:26 pm UTC
Forum: Mathematics
Topic: Transforming to positive
Replies: 8
Views: 2087

### Re: Transforming to positive

dudiobugtron wrote:
Sizik wrote:x1/2 is multivalued.

Unless x = 0.

You obviously haven't encountered negative zero!
Sun Dec 02, 2012 10:40 pm UTC
Forum: Mathematics
Topic: problems for fun! Volume of a cone as a function of height
Replies: 33
Views: 4255

### Re: problems for fun! Volume of a cone as a function of heig

It's much easier to do it without half a dozen variables. Forget about all the r 1 , r 2 , h 1 , h 2 , etc. stuff. Since the radius increases linearly as you go down the height axis from the pointy end, you can just use some coefficients, like so: V fullcone = 1/3 π r 2 h V frustum = 1/3 π r 2 h - 1...
Sat Nov 24, 2012 5:14 pm UTC
Forum: Hardware
Topic: WiFi with antisnooping but without passwords?
Replies: 4
Views: 3296

### Re: WiFi with antisnooping but without passwords?

KnightExemplar wrote:Https

Yeah, that's true (and I use that), but I mean for the entire link. Even with HTTPS, people can still easily guess which server you're connecting to. And of course there are lots of sites (particularly those where you don't log in) that don't support HTTPS.
Sat Nov 24, 2012 12:05 am UTC
Forum: Religious Wars
Topic: QWERTY versus Dvorak
Replies: 166
Views: 88603

### Re: QWERTY versus Dvorak

I personally prefer Dvorak because it seems more comfortable for my hands somehow, though I wonder if any of the other popular alternatives have this as well. I think it has something to do with the fact that, as a raptor, moving my ring finger or middle finger down below the rest of my fingers is q...
Fri Nov 23, 2012 10:06 pm UTC
Forum: Logic Puzzles
Topic: Can anyone decode this?
Replies: 4
Views: 3269

### Re: Can anyone decode this?

I could be wrong, but I think there's not really enough ciphertext to work with.
Fri Nov 23, 2012 8:29 pm UTC
Forum: General
Topic: REALLY Annoying Misconceptions
Replies: 4059
Views: 379333

### Re: REALLY Annoying Misconceptions

I'm fine with people believing that because they did a study to see whether raptors do in fact hate goto statements. There were no survivors. But the raptors survived quite well! :mrgreen: Thus, I think your methodology is flawed. It was a double-blind study, in that both of the lead researcher's e...
Fri Nov 23, 2012 8:21 pm UTC
Forum: Computer Science
Topic: Ambiguous cases and Asimov's Three Laws of Robotics
Replies: 50
Views: 41707

### Re: Ambiguous cases and Asimov's Three Laws of Robotics

So the question is "why would we want robots who can't murder people who force them to work without pay?" :wink: No, I mean enslaved humans or other kinds of victims. Self defense is widely considered very useful, yet if those people had such robots, the robots would essentially be like b...
Fri Nov 23, 2012 8:12 pm UTC
Forum: Hardware
Topic: WiFi with antisnooping but without passwords?
Replies: 4
Views: 3296

### WiFi with antisnooping but without passwords?

It seems like you can only get antisnooping features (one user can't snoop on another's connection) with WPA2 and a password. Even though they both know the network password, they supposedly still can't read each others' transmissions. Is there something like this for passwordless access points? I m...
Fri Nov 23, 2012 1:23 am UTC
Forum: Logic Puzzles
Topic: Another Cipher
Replies: 1
Views: 2022

### Re: Another Cipher

I haven't solved it, but I found an interesting thing about most of the numbers. The numbers seem to mostly be clustered around numbers with lots of repeated factors. I think this is why they have a few that are close, but then they're separated from the next by huge jumps. 3 2 - 2 4 2 + 4 6 2 -...
Thu Nov 22, 2012 7:50 pm UTC
Forum: Logic Puzzles
Topic: What w/could you do with a P algorithm for factorisation?
Replies: 6
Views: 2289

### Re: What w/could you do with a P algorithm for factorisation

As has been pointed out before, P doesn't mean feasible. For instance, an algorithm with time in Θ(n 19849839482824 ) would not be very fast, though it would be a polynomial-time one for sure. You should probably replace 'P algorithm' in the question with 'feasible algorithm' or 'quick algorithm' or...
Thu Nov 22, 2012 7:15 pm UTC
Forum: Logic Puzzles
Topic: Troll Science: Pi
Replies: 45
Views: 26550

### Re: Troll Science: Pi

On the other hand, how did ancient mathematicians estimate the value of pi? By constructing inscribed and circumscribed polygons and computing their perimeters. How come this limit works, but the original one doesn't? Because they were geometry experts who knew that angles matter quite a lot with r...
Thu Nov 22, 2012 5:27 pm UTC
Forum: General
Topic: Kill Hitler
Replies: 15
Views: 6292

### Re: Kill Hitler

Genghis Khan, people. Genghis Khan. As far as Hitler stuff, One intriguing consequence of preventing WW2 I've seen played with is that, without the massive efforts to break Axis codes during the war, computer technology might not advance much beyond basic analog computers. This would cripple most sc...
Wed Nov 21, 2012 7:20 pm UTC
Forum: General
Topic: REALLY Annoying Misconceptions
Replies: 4059
Views: 379333

### Re: REALLY Annoying Misconceptions

I hate when a technical term specific to a technology that will probably be obsolete soon enough is used for something general. I can understand xerox for a specific kind of copying, but In just about all cases, there's already a perfectly exact term...that no one uses. Bandwidth is not throughput, ...
Wed Nov 21, 2012 6:33 pm UTC
Forum: Computer Science
Topic: Paying with Google Wallet or facial recognition
Replies: 18
Views: 21386

### Re: Paying with Google Wallet or facial recognition

You're saying identical twins would be the reason this wouldn't work? Seriously? Because it's so hard to use someone else's credit card It's not identical twins trying to fool the system, it's identical twins being unable to not fool the system. It would be unusable for them as a simple system and ...
Wed Nov 21, 2012 6:22 pm UTC
Forum: Computer Science
Topic: Ambiguous cases and Asimov's Three Laws of Robotics
Replies: 50
Views: 41707

### Re: Ambiguous cases and Asimov's Three Laws of Robotics

I'm not sure why Asimov's fictional three laws are considered worth much. They made for some interesting stories perhaps, but they aren't that good, and it's not because of ambiguity of any kind. Loss of life is important, but who values that to the exclusion of all else? Humans trying to be moral d...
Wed Nov 21, 2012 6:04 pm UTC
Forum: Computer Science
Topic: Ambiguous cases and Asimov's Three Laws of Robotics
Replies: 50
Views: 41707

### Re: Ambiguous cases and Asimov's Three Laws of Robotics

Yeah. If you program it to intervene of its own volition, how will it respond to the situation where there's six people each with a different organ failing who'll die without a transplant - and one person with all healthy organs... The healthy person is irrelevant and included improperly for emotio...
Wed Nov 21, 2012 5:02 pm UTC
Forum: Computer Science
Topic: Algorithm to Prevent Password Re-Use
Replies: 24
Views: 25096

### Re: Algorithm to Prevent Password Re-Use

Oh I'm well aware of this. But think about the typical non-security-aware user. Oh, I see. Yeah, that's a good point. I don't think there's much to be done about it because most people in charge of things are like those users and don't care too much about thinking through things or delegating desig...
Tue Nov 20, 2012 10:51 pm UTC
Forum: Computer Science
Topic: Fastest Way to Determine if a # Belongs in a Combination
Replies: 5
Views: 11723

### Re: Fastest Way to Determine if a # Belongs in a Combination

With the standard lexicographic ordering ((1, 2, 3), (1, 2, 4), (1, 2, 5), (1, 3, 4), ...), it's not so hard to compute recursively since there are some nice recursive (fractal?) patterns to where a number shows up. module Combos where choose n k = div (product [n - k + 1..n]) (product [...
Tue Nov 20, 2012 5:02 pm UTC
Forum: Computer Science
Topic: Algorithm to Prevent Password Re-Use
Replies: 24
Views: 25096

### Re: Algorithm to Prevent Password Re-Use

Why are financial companies so bad at security? (My mother's maiden name is a matter of public record for christ's sake!) You know...you don't have to use your mother's maiden name for that. You can make up a name. That's what I usually do. If it's a form, you can put whatever you want, even if it ...
Tue Nov 20, 2012 1:09 pm UTC
Forum: Mathematics
Topic: "Simplest Conceivable"
Replies: 54
Views: 8821

### Re: "Simplest Conceivable"

Not to be flippant, but this is a bit like those related analogy questions on standardized tests... addition : complex numbers, etc. dots : all sorts of things you can draw, all of geometry, etc. ...where the analogy is what something leads to when developed further. The simplicity of something is n...
Tue Nov 20, 2012 12:59 pm UTC
Forum: Mathematics
Topic: a simple question of probability
Replies: 4
Views: 1431

### Re: a simple question of probability

There's a general way to solve this kind of problem. As you can see, there are four possible sides you could have chosen. Which of those sides match what you're looking at (a heads side)? Of the sides you might be looking at, which of them would fit the desired quality (has heads on the other side)?...
Mon Nov 19, 2012 4:45 pm UTC
Forum: Coding
Topic: Roller Coaster Tycoon in... Assembly?
Replies: 39
Views: 38651

### Re: Roller Coaster Tycoon in... Assembly?

I have no idea how one would accomplish anything beyond a basic complexity. Obviously large programs have been written in assembly. My question is How? If you're an object oriented programmer, assembly languages have procedures (like methods) that you can call. So you can design a data structure an...
Mon Nov 19, 2012 2:10 pm UTC
Forum: Mathematics
Topic: Identifying a modular base
Replies: 4
Views: 1334

### Re: Identifying a modular base

From a large chunk of simulation, it seems that almost at random, 1/4 numbers are residues for a given larger modular base. If so, then a residue should let us eliminate about 3/4 of bases of a given size. So for an N bit base, we expect N/2 residues to be the expected number of residues to lock it...