Search found 2077 matches

by jaap
Thu Apr 10, 2008 2:29 pm UTC
Forum: Coding
Topic: BigInt class
Replies: 14
Views: 2625

Re: BigInt class

which appears quite erroneous seeming as eg prime 99 is lower than prime 98 - the bigint class is wrapping I imagine, or just fails. It is indeed obviously wrapping. Your program's logic still fails though, even with the +1. If you multiply primes, and add 1, then the result is not guaranteed to be...
by jaap
Wed Apr 09, 2008 11:50 am UTC
Forum: Language/Linguistics
Topic: Spreek Nederlands en Praat Afrikaans (Dutch & Afrikaans)
Replies: 418
Views: 130750

Re: Spreek Nederlands en Praat Afrikaans (Dutch & Afrikaans)

Why is it hier kan je and not hier je kan ? I thought the subject preceedes the verb except for questions. That's a good question. I never realised before that this is a construct where Dutch and German differ from English. It most often happens when a sentence starts with a place ('Hier', 'Daar', ...
by jaap
Wed Apr 09, 2008 6:53 am UTC
Forum: Language/Linguistics
Topic: Spreek Nederlands en Praat Afrikaans (Dutch & Afrikaans)
Replies: 418
Views: 130750

Re: Spreek Nederlands en Praat Afrikaans (Dutch & Afrikaans)

Hier jij kan spreek Nederlands (of Engels als jij wilt) en leer de Nederlands taal. The Dutch version should be: Hier kan je Nederlands spreken (of Engels als je wilt) en de Nederlandse taal leren. I think most verb forms in Afrikaans have been somewhat simplified compared to Dutch. Ik denk dat de ...
by jaap
Wed Apr 09, 2008 6:41 am UTC
Forum: Language/Linguistics
Topic: Proverb becoming obsolete
Replies: 12
Views: 3163

Re: Proverb becoming obsolete

"Out of sight, out of mind" What about absence makes the heart grow fonder ? Minor derail: I once heard of a self-help book where every piece of advice was (deliberately) directly contradicted elsewhere in the book, with everything completely plausible, often backed up by cliché proverbs ...
by jaap
Fri Apr 04, 2008 9:56 am UTC
Forum: Coding
Topic: The "IT DOESN'T WORK!" thread
Replies: 1958
Views: 524875

Re: The "IT DOESN'T WORK!" thread

What this code is supposed to be doing is, given a set of input ranges of the form "lower higher", consolidates all overlapping range into one range, and stores all non-overlapping ranges in a list. I think your code's logic needs a rethink. You are using a nested loop in a confusing way,...
by jaap
Mon Mar 24, 2008 6:09 pm UTC
Forum: Coding
Topic: The "IT DOESN'T WORK!" thread
Replies: 1958
Views: 524875

Re: The "IT DOESN'T WORK!" thread

Anyway, the code works - I mean it reads info from the file, it just doesn't work how it should - I get the wrong info in the wrong fields or something. That's because you create/add a new student after every line that's read instead of after every four lines. You are doing it all in a very roundab...
by jaap
Tue Mar 11, 2008 5:33 pm UTC
Forum: Coding
Topic: Simple sorting pogram in TASM
Replies: 1
Views: 1612

Re: Simple sorting pogram in TASM

I'm making a simple sort program in tasm but I'm not very good, I've got it to work with numbers (as seen below) but i have no idea how to get it to sort a list of strings in assembly. When working with larger data structures, such as strings, you don't really want to move them about in memory if y...
by jaap
Sat Mar 08, 2008 1:01 am UTC
Forum: Coding
Topic: Help me read a post about 3d arrays? (C++)
Replies: 5
Views: 1648

Re: Help me read a post about 3d arrays? (C++)

First method: // Allocate it: float *tmp = new float[dim1*dim2*dim3]; // Access element x,y,z: (where x<dim1, y<dim2, z<dim3 ) tmp[ ( x * dim2 + y ) * dim3 + z ] = 0; // Free it: delete[] tmp; Note the brackets in the expression to access an element. The code you have may be incorrect, depending on ...
by jaap
Sun Mar 02, 2008 7:54 am UTC
Forum: Mathematics
Topic: Summing of digits in numbers
Replies: 19
Views: 3379

Re: Summing of digits in numbers

Wow, I hadn't thought of it that way before. I tried to brute force the problem by counting the number of cases you can get without the restriction 0 <= x i <= 9 and then count the number of violations of the restrictions (the calculations got to be very cumbersome past sum = 20). The method of dis...
by jaap
Fri Feb 29, 2008 7:16 pm UTC
Forum: Mathematics
Topic: Imaginary negative
Replies: 17
Views: 3532

Re: Imaginary negative

Any moment now a moderator will come in and lock this thread because it's been discussed before: http://forums.xkcd.com/viewtopic.php?f=17&t=15496 ... hmmm... URL for this thread: http://forums.xkcd.com/viewtopic.php?f=17&t=15496 URL for that thread: http://forums.xkcd.com/viewtopic.php?f=1...
by jaap
Fri Feb 29, 2008 10:33 am UTC
Forum: Mathematics
Topic: Imaginary negative
Replies: 17
Views: 3532

Re: Imaginary negative

Any moment now a moderator will come in and lock this thread because it's been discussed before:
viewtopic.php?f=17&t=15496
by jaap
Thu Feb 28, 2008 8:23 pm UTC
Forum: Science
Topic: argon fish tank
Replies: 28
Views: 5564

Re: argon fish tank

I think the following video is appropriate: Ship floating on heavy gas (Hexafluoride) with the amount of heavy air it displaces, its drastically different than water being the floating mechanism. Gas can be heavier than Gas, but Gas will not be heavier than most liquids and solids. I'm sure someone...
by jaap
Thu Feb 28, 2008 5:58 pm UTC
Forum: Science
Topic: argon fish tank
Replies: 28
Views: 5564

Re: argon fish tank

I think the following video is appropriate:
Ship floating on heavy gas (Hexafluoride)
by jaap
Sun Feb 24, 2008 5:39 pm UTC
Forum: Mathematics
Topic: Algorithm for Factoring Large Numbers
Replies: 8
Views: 1556

Re: Algorithm for Factoring Large Numbers

The only consecutive powers (prime powers or not) are 8=2^3 and 9=3^2.

http://en.wikipedia.org/wiki/Catalan%27s_conjecture
by jaap
Sat Feb 23, 2008 9:55 pm UTC
Forum: Mathematics
Topic: Differental calculus.
Replies: 5
Views: 1093

Re: Differental calculus.

Parallel lines have the same slope.
What is the slope of the line 14x - 2y + 7 = 0 ?
If you have a tangent line to the curve y = x³ + 3x² - 3x + 2, what do you know about its slope?
When are the two equal?
by jaap
Sat Feb 23, 2008 4:06 pm UTC
Forum: Coding
Topic: Rubiks Cube Solver
Replies: 20
Views: 3022

Re: Rubiks Cube Solver

A summary of the current state of knowledge is as follows: There are more than 30,000 positions known that need 20 face turns[1] (for example superflip) but no position which needs 21 or more face turns. There exists a fast algorithm that can always solve in 26 face turns. There exists a position t...
by jaap
Sat Feb 23, 2008 10:51 am UTC
Forum: Mathematics
Topic: Question I've Got
Replies: 11
Views: 1457

Re: Question I've Got

As MrBaggins said, there isn't much that can be said for the probability at any particular distance from the exploding ship. It really depends on the number and size of the pieces. There are two ways of looking at this. First, the question you asked: "What is the probability of any piece of the...
by jaap
Mon Feb 18, 2008 3:59 pm UTC
Forum: School
Topic: I have an awesome textbook
Replies: 90
Views: 9817

Re: I have an awesome textbook

My schoolbooks didn't have any funnies, though my physics teacher did set a neat test once about James Bond, that had questions like "Blofeld has caused a toxic rainstorm to erupt above Bond's head. Luckily, Q has equipped Bond with an umbrella. Given a rain speed of ...kph, at what angle must ...
by jaap
Fri Feb 08, 2008 12:59 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0381: "Mobius Battle"
Replies: 122
Views: 32844

Re: "Mobius Battle" Discussion

Mulch wrote:For some reason, this strip just doesn't seem as edgy as xkcd normally is.


Hahaha! Very good.

Spoiler:
A Moebius strip only has one edge...
by jaap
Tue Feb 05, 2008 10:35 pm UTC
Forum: Mathematics
Topic: Set "Relations" question...is work safe
Replies: 4
Views: 1111

Re: Set "Relations" question...is work safe

In an example we are told to find the smallest reflexive symmetric relation. A={a,b,c,d,e} S={(a,a), (a,b), (b,c), (b,d), (c,e), (e,d), (c,b)} You then mention "sets within that set". That is not right. It is a set of ordered pairs. Each pair in S shows two elements that satisfy the relat...
by jaap
Tue Jan 22, 2008 7:43 am UTC
Forum: Mathematics
Topic: Topology and Sets
Replies: 1
Views: 881

Re: Topology and Sets

I am stuck on a problem with my topo homework. Let S and T be sets,and f: S-->T be bijective, and let B be a proper subset of T. Show that the image of B under f -1 is the inverse image of B under f. I figure that this is pretty obvious but I am not sure how to show this. There are two sets here th...
by jaap
Mon Jan 21, 2008 6:13 pm UTC
Forum: Mathematics
Topic: Work and Fluid Force -- Calculus Problem (Please help.)
Replies: 7
Views: 2991

Re: Work and Fluid Force -- Calculus Problem (Please help.)

I drew the trapezoid on the coordinate plane, with the y-axis bisecting it. It has vertices at (-3, 4), (3, 4), (-1.5, 0), (1.5, 0). In terms of y, the right side of the trapezoid is f(y) = (8y/3) + (32/3). That's not right. If x=f(y), you should have f(0)=1.5 and f(4)=3. I get: x = y * 3/8 + 3/2 I...
by jaap
Wed Jan 16, 2008 9:47 am UTC
Forum: Language/Linguistics
Topic: Words that no longer seem to be words
Replies: 99
Views: 16414

Re: Words that no longer seem to be words

Actually, silent 'e's are fairly consistently (for English anyway) used to denote the extension of a vowel sound. Some choice examples are "cap" and "cape", "not" and "note" and "tot" and "tote". I still quite vividly remember the video th...
by jaap
Wed Nov 14, 2007 10:48 am UTC
Forum: Mathematics
Topic: functions-dimensions
Replies: 6
Views: 1207

Re: functions-dimensions

when trying to solve for x, i get 24w(w^2-6)+120=0....i don't know where to go from here, what happens to the 120? without it i would get w=0 and w=2.45 (You mean "solve for w ") You want to solve 24( w^3 -6w + 5 ) = 0. First factor the left hand side (hint: w=1 is one easy to spot soluti...
by jaap
Mon Nov 05, 2007 8:46 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0338: "Future"
Replies: 140
Views: 20163

Re: "Future" Discussion

Here is another comic that goes across panels into the future:
Image
From Bob the Angry Flower.
by jaap
Tue Oct 16, 2007 8:04 am UTC
Forum: Science
Topic: Impossible Circuit
Replies: 20
Views: 3640

Re: Impossible Circuit

The only thing I can think of right now with my fatigue-riddled brain involves a complicated scheme of an AC power supply and a fistful of diodes. I would propose this solution: AC power supply. Each lightbulb is actually an LED wired parallel to a resistor. The LEDs in the bulbs are wired in oppos...
by jaap
Wed Oct 03, 2007 7:40 am UTC
Forum: Science
Topic: Electricity Consumption
Replies: 12
Views: 1554

Re: Electricity Consumption

Given the initial data, your results look correct to me too. Just a minor simplification - you said: 2.250.000.000kWh And that would be 71,3 kWh by second. Why go down to the energy usage per second? It is easier to go to energy per hour, since you already have it in units of kWh. In other words: 2....
by jaap
Wed Oct 03, 2007 6:45 am UTC
Forum: Science
Topic: Favorite home experiments
Replies: 585
Views: 449542

Re: Favorite home experiments

This one is really cool and easy to do: homopolar motor. In that version it is the wire that spins. There is also a version called the Maxwell Motor which has the magnet spinning. The only extra equipment is a nail or screw, and optionally a paperclip. It is best if the magnet is more cylindrical r...
by jaap
Thu Sep 13, 2007 7:32 am UTC
Forum: Language/Linguistics
Topic: Words you love.
Replies: 680
Views: 131570

I like the words aviary and idiocy, for the large number of syllables in such short words.
by jaap
Thu Aug 16, 2007 6:20 am UTC
Forum: Mathematics
Topic: WLOG
Replies: 7
Views: 2952

Re: WLOG

What does "without loss of generality" mean and when should it be used? "Without loss of generality assume that P" means that the restriction P placed on the objects being studied is not really a restriction - it just makes the proof less messy. Often P is a restriction that som...
by jaap
Tue Aug 14, 2007 2:09 pm UTC
Forum: Science
Topic: Synchronized wheels
Replies: 13
Views: 2960

Anyway, it is probably confirmation bias as skeptical scientist said. Note that some car brands (e.g. Rolls Royce) have wheel badges that don't turn with the wheels, so a stationary car will always have their logos exactly upright. You know, I think that just answered his question. At least it woul...
by jaap
Tue Aug 14, 2007 11:29 am UTC
Forum: Science
Topic: Synchronized wheels
Replies: 13
Views: 2960

Whatever pattern is on the wheels has the same orientation? This strikes me as coincidence+confirmation bias, since there is no reason why an orientation of the rear wheel matching that of the front wheel should be more likely than any other orientation - whenever the car turns or skids, there is a...
by jaap
Thu Aug 02, 2007 1:17 pm UTC
Forum: Mathematics
Topic: A couple random ideas
Replies: 2
Views: 1360

Re: A couple random ideas

And for the grammar people out there, I use punctuation horribly and the only reason I can spell is ... Other than Pole/Poll your post seems fine to me. ... because firefox complains if I misspell it. (Funny thing, both 'firefox' and 'math' are misspelled according to firefox) I think you may be us...
by jaap
Thu Jul 26, 2007 11:58 am UTC
Forum: Science
Topic: Constructive use of Nukes
Replies: 54
Views: 6470

Swordfish, what percentage of the earth's surface consists of building roofs? Now explain to me how painting that percentage of the earth white will have any noticeable effect at all. Radius of earth 6000km 4/3pir^3=904778684234km^2 That's the volume of the earth in km^3. You want 4pi r^2 for the s...
by jaap
Tue Jul 17, 2007 12:30 pm UTC
Forum: Science
Topic: Favorite home experiments
Replies: 585
Views: 449542

The microwave produces "standing waves". ... The distance between the points (either between minimums or between maximums) is exactly the wavelength of the radiation in the microwave. Not quite - that distance is exactly half the wavelength. Sometimes when I watch tv and have a rubber ban...
by jaap
Tue Jul 10, 2007 11:01 am UTC
Forum: General
Topic: Seeing yourself in stories
Replies: 22
Views: 3014

Slightly deviation but since my name is Christopher Stern, I was pretty freaked when my friend brought in a game magazine with a preview for Headhunter. (A guy called Christopher Stern gets killed in the game) I was pretty freaked too when I did an ego-google and found a short story someone had wri...
by jaap
Fri Jul 06, 2007 7:17 am UTC
Forum: Mathematics
Topic: Rounding errors in scientific calculators
Replies: 10
Views: 3541

987654321/8 = ANS = 123456790.1 ANS*8 = 987654321 123456790.1*8 = 987654320.8 it still gives the same rounding error. Calculators always internally store more digits than can be shown on the screen. Yours seems to show 10 digits, but actually has at least 12. Try this: 1/3 = 0.333333333 x 100000 = ...

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