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MATH

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    the wookthe wook Registered User regular
    edited May 2008
    Dely Apple wrote: »
    itt 99 pages arguing about the goat/door probability game

    I don't know what that is, but I'm all for more goats

    the wook on
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    SirToastySirToasty Registered User regular
    edited May 2008
    Don't you have a better chance of winning if you change your selection? I read this somewhere.

    SirToasty on
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    Metzger MeisterMetzger Meister It Gets Worse before it gets any better.Registered User regular
    edited May 2008
    I'm not good at math. Most of it is fairly easy for me, but sometimes that shit just lookes like someone throwing a bunch of symbols together to fuck with me.

    My strength is writin'.

    Metzger Meister on
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    TheidarTheidar Registered User regular
    edited May 2008
    I have forgotten 90% of the higher math I learned.

    I look at calculus or trig now and have to shake my head sadly at all my lost skills.

    Theidar on
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    VeegeezeeVeegeezee Registered User regular
    edited May 2008
    Math is so much cooler when it's describing something physical.

    Like trebuchet mechanics. (pdf)

    Veegeezee on
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    L|amaL|ama Registered User regular
    edited May 2008
    Did you guys know that Newton probably had Asperger's?

    And his proof of 1+1=2 took up a whole book.

    Didn't he maybe die a virgin too? So don't try and cite that shit, wiggin.


    Four is a pretty big number, in its way. If I had four elephants in my room right now, I'd be thinking, "What a lot of elephants".

    You remind me of my calc teacher, this is the kind of stuff he would say. He's also pretty crazy, and makes racist remarks without realising it. "Me and this guy? see we don't need these (throws $100 school graphics calculator in bin). We're Korean, we're smart."
    He's white.

    L|ama on
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    TossrockTossrock too weird to live too rare to dieRegistered User regular
    edited May 2008
    Framling wrote: »
    So anywy, Graham's number.

    First, I have to explain arrow notation, it's not too hard. Basically, it's like super-exponents.

    4^3 = 4*4*4, right? Well, along those lines, 4^^3 = 4^4^4. This goes right to left, so 4^4^4 = 4^256 = a pretty huge number.

    Anyway, it continues like that, so 6^^^^^4 = 6^^^^6^^^^6^^^^6.

    These numbers get unbelievably huge really quickly. for example, there's this sequence of numbers called Ackermann numbers. it goes 1^1, 2^^2, 3^^^3, 4^^^^4, and so on.
    • 1^1 = 1
    • 2^^2 = 2^2 = 4
    • 3^^^3 = 3^^3^^3 = 3^^7625597484987 = 3^3^3^3^...^3 (with 7625597484987 3's) = a number too huge to ever possibly hope to write out.

    So anyway, that's Knuth Arrow notation in a nutshell.

    Now, let's assume that g_0 = 3^^^^3. That's a three, four arrows, and another three. omghueg. That's g_0.

    Now let's further assume that g_n = 3^^^^^...^3, with g_(n-1) ^'s. What. Yeah.

    Graham's number is g_64.

    Ronald Graham was my discrete math professor

    8-)

    Also, you know what's cool?

    Gabriel's Horn


    It has infinite surface area (2 pi ln(a), as a=> infinity) but finite volume (pi * (1 - 1/a), as a=> infinity)

    meaning you could fill it with paint, but you couldn't paint it

    crazy, huh

    Tossrock on
    sig.png
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    Me Too!Me Too! __BANNED USERS regular
    edited May 2008
    I love physics simply because it's math that describes how things act in the real world

    Me Too! on
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    TaramoorTaramoor Storyteller Registered User regular
    edited May 2008
    Since this is a Math thread, I need someone to explain the goddamn Monty Hall problem.

    Monty shows you three doors. Behind one is a car. Behind the other two are goats.

    You pick a door, and Monty opens another door to reveal a goat.

    Monty then offers you the chance to switch your door selection to the remaining unopened door.

    Now, are your odds of getting the car better if you switch or if you stay on the door you originally picked?

    Taramoor on
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    Me Too!Me Too! __BANNED USERS regular
    edited May 2008
    Odds are better if you switch
    I know this one because I read Curious Incident of the Dog in the Nighttime
    Give me a minute to type it up and I'll explain it

    Me Too! on
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    TossrockTossrock too weird to live too rare to dieRegistered User regular
    edited May 2008
    Taramoor wrote: »
    Since this is a Math thread, I need someone to explain the goddamn Monty Hall problem.

    Monty shows you three doors. Behind one is a car. Behind the other two are goats.

    You pick a door, and Monty opens another door to reveal a goat.

    Monty then offers you the chance to switch your door selection to the remaining unopened door.

    Now, are your odds of getting the car better if you switch or if you stay on the door you originally picked?

    they are better when you switch

    you can see why if you use larger numbers:

    Imagine there are 100 doors, and you pick one. The guy opens 98 empty doors, leaving yours and one other.

    Should you switch? Obviously; the chances of you picking the right one straight off the bat were only 1/100, meaning the other door almost certainly holds the prize, despite the fact that there are "50/50" odds.

    The same holds true even when there are only 3 doors. Your chance of picking the correct one straight off the bat were 1/3; the chance of the other door being correct is 1/2.

    Tossrock on
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    Me Too!Me Too! __BANNED USERS regular
    edited May 2008
    For this example, let's say that the car is behind Door C
    Say you pick Door A, and the host opens Door B to reveal a goat
    Now you have to make a choice between staying with Door A or changing to Door C.
    If you change to C, you get the car
    Same thing happens if you pick B and change to C once A is opened. If you pick C and change, though, you get a goat.
    So, out of three times, you get the car two times if you change the door
    Whereas staying with the same door only gets you the car 1/3 times

    Me Too! on
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    stimtokolosstimtokolos Registered User regular
    edited May 2008
    I'm doing Multi-Variable calculus in my maths subject right now, it is ok I guess. At least we don't dwell on shit for weeks on end like in highschool, that was fucking lame.

    "So you did the top grade maths, yeah lets just fuck around with the same subject for 5 hours or so a week for a month. Ain't no big."

    I actually didn't do very well in that class (better than the majority of the people and for determine your ENTER which is to do with university entrance here it gets scaled up an assload compared with other subjects but I'm straying from the point) but I understand more of the shit I'm doing now in this more complex course because I don't just fall asleep in class or not do anything because I'm bored by the pace.

    stimtokolos on
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    FramlingFramling FaceHead Geebs has bad ideas.Registered User regular
    edited May 2008
    Tossrock wrote: »
    Framling wrote: »
    So anywy, Graham's number.

    First, I have to explain arrow notation, it's not too hard. Basically, it's like super-exponents.

    4^3 = 4*4*4, right? Well, along those lines, 4^^3 = 4^4^4. This goes right to left, so 4^4^4 = 4^256 = a pretty huge number.

    Anyway, it continues like that, so 6^^^^^4 = 6^^^^6^^^^6^^^^6.

    These numbers get unbelievably huge really quickly. for example, there's this sequence of numbers called Ackermann numbers. it goes 1^1, 2^^2, 3^^^3, 4^^^^4, and so on.
    • 1^1 = 1
    • 2^^2 = 2^2 = 4
    • 3^^^3 = 3^^3^^3 = 3^^7625597484987 = 3^3^3^3^...^3 (with 7625597484987 3's) = a number too huge to ever possibly hope to write out.

    So anyway, that's Knuth Arrow notation in a nutshell.

    Now, let's assume that g_0 = 3^^^^3. That's a three, four arrows, and another three. omghueg. That's g_0.

    Now let's further assume that g_n = 3^^^^^...^3, with g_(n-1) ^'s. What. Yeah.

    Graham's number is g_64.

    Ronald Graham was my discrete math professor

    8-)

    Also, you know what's cool?

    Gabriel's Horn


    It has infinite surface area (2 pi ln(a), as a=> infinity) but finite volume (pi * (1 - 1/a), as a=> infinity)

    meaning you could fill it with paint, but you couldn't paint it

    crazy, huh

    My Calc teacher showed us Gabriel's Horn once and it blew my mind.

    Another time he taught us about the Devil's Staircase. It's continuous between x=0 and x=1, and has a derivative of 0 almost everywhere (its slope is undefined on a countably infinite set of points, meaning 0% of the domain), and yet it goes from (0,0) to (1,1)

    He was the best math teacher I ever had.

    Framling on
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    Metzger MeisterMetzger Meister It Gets Worse before it gets any better.Registered User regular
    edited May 2008
    That doesn't make fucking sense how can something be finite in volume but infinite in surface area this is fucking bullshit.

    Metzger Meister on
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    Airking850Airking850 Ottawa, ONRegistered User regular
    edited May 2008
    I had the best math teacher in high school.

    He was a stuffy british dude that looked like Adam West. He was so invested in all of his students, and was so genuinely sad whenever we didn't try our hardest, and just so good at teaching that everyone loved him.

    One day he came into class, slammed the door behind himself and started shouting about how our test scores were down from the last unit, and we weren't paying attention in class, and we were becoming terrible students. Our class was mortified that we had upset him. He started drilling us all, yelling "TOO SLOW! NEXT PERSON! NONE OF YOU HAVE BEEN PAYING ANY ATTENTION IN CLASS!!" when people didn't have answers right away. The entire class was frozen in our chairs thinking oh fuck oh fuck why is he freaking out like this ...and then the biggest smile crossed his face and he said, "today we're going to learn about the cross product. hahaha!"

    The class was so horrified that it took us about thirty seconds before we actually realised that he was fucking with us.

    Airking850 on
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    FavlaudFavlaud just straight up awful Registered User regular
    edited May 2008
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    thorgotthorgot there is special providence in the fall of a sparrowRegistered User regular
    edited May 2008
    i was just thinking about posting that

    also: quick reply does not interrupt video watching

    thorgot on
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    Airking850Airking850 Ottawa, ONRegistered User regular
    edited May 2008
    We also did a whole lot of note-passing during that math class. One day near the end of the year our teacher decided to actually call us on it; of course, he chose the classic route and asked me to read what I was writing out loud to everyone. So I stood up, walked to the front of the class, cleared my throat and read what I had just written:

    "Why did no one like the two vectors? Because they were always co-planing!"

    I walked back to my seat while the class and the teacher just stared in disbelief.

    Airking850 on
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    SageinaRageSageinaRage Registered User regular
    edited May 2008
    Yeah, the thing that threw me about the monty hall problem (and most people) is that they only start thinking about probability once you're down to two doors, when there's really three separate cases, since you start with 3 doors, and they're all equally probable:

    case 1: you picked the right door - you shouldn't switch
    case 2: you picked the wrong door - you should switch
    case 3: you picked the other wrong door - you should switch

    SageinaRage on
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    JunpeiJunpei Registered User regular
    edited May 2008
    The last scene in that video belongs in the blingee thread.

    Junpei on
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    WeaverWeaver Who are you? What do you want?Registered User regular
    edited May 2008
    Framling I'm sorry dude but mathematical concepts that are infinite or physically impossible excite me just about as much as showing my work for Pi, measuring the event horizon of a super-massive black hole or writing an original proof on why anonymity+internet=dick

    Weaver on
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    KingAgamemnonKingAgamemnon Registered User regular
    edited May 2008
    That doesn't make fucking sense how can something be finite in volume but infinite in surface area this is fucking bullshit.

    Put very simply, the function 1/x is rotated around the x-axis, giving us a horn shape. Normally 1/x has an asymptote (a singularity on the graph, usually somewhere where you've divided by 0) at 0, but Gabriel's horn has intervals that start at x>=1 it is effectively cut off from the region of the graph where it starts "stretching" to infinity (this would have been at x=0).

    Well, that roughly explains the finite volume. As far as infinite surface area, I don't quite remember.

    I do know that the derivative of an anti-derivative (i.e. volume) is surface area. Possible that using the fundamental theorem of calculus the derivative of integral[1/x] with interval [1,inf) is infinity.

    KingAgamemnon on
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    KovakKovak did a lot of drugs married cher?Registered User regular
    edited May 2008
    i love maths

    Kovak on
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    KovakKovak did a lot of drugs married cher?Registered User regular
    edited May 2008
    That doesn't make fucking sense how can something be finite in volume but infinite in surface area this is fucking bullshit.

    Put very simply, the function 1/x is rotated around the x-axis, giving us a horn shape. Normally 1/x has an asymptote (a singularity on the graph, usually somewhere where you've divided by 0) at 0, but Gabriel's horn has intervals that start at x>=1 it is effectively cut off from the region of the graph where it starts "stretching" to infinity (this would have been at x=0).

    Well, that roughly explains the finite volume. As far as infinite surface area, I don't quite remember.

    I do know that the derivative of an anti-derivative (i.e. volume) is surface area. Possible that using the fundamental theorem of calculus the derivative of int(1/x) with interval [1,inf) is infinity.

    the math just kinda says it does

    but to try to explain in plain words


    The volume if you imagine the small end gets smaller and smaller till eventually an addition of volume is not really adding anyhting

    The limit of the extra volume approaches 0. However, the surface area that provides that volume does not go to 0.

    I can post the math I guess.

    Kovak on
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    musanmanmusanman Registered User regular
    edited May 2008
    what's up with zero factorial equaling 1

    I mean, that's bullshit.

    also I know like 3 proofs for it I don't care what the maths say

    musanman on
    sic2sig.jpg
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    KingAgamemnonKingAgamemnon Registered User regular
    edited May 2008
    musanman wrote: »
    what's up with zero factorial equaling 1

    I mean, that's bullshit.

    also I know like 3 proofs for it I don't care what the maths say

    It has something to do with a special case of the Zeta Function

    Kind of complicated, so unless you take some upper level math courses, it is just defined as 1.

    KingAgamemnon on
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    KingAgamemnonKingAgamemnon Registered User regular
    edited May 2008
    woops gamma function not zeta function

    KingAgamemnon on
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    KovakKovak did a lot of drugs married cher?Registered User regular
    edited May 2008
    Math for Gabriel's Horn

    Taking the function 1/x and revolving it around the X axis, on the interval 1<=x<infinity

    The volume of this solid is given by the integrand

    F = pi * integral(1/x^2), [the integral is from 1 to infinity]

    Which gives

    lim a -> infinity pi * -1/a + 1

    Thus the volume of the "horn" is pi

    However, the surface area is defined as

    2pi * integral[(1/x) * sqrt[1 + (1/x^4)] [evaluated from 1 to infinity]

    This results in

    -(1/2) Sqrt[1 + 1/x^4] + (Sqrt[1 + 1/x^4] x^2 ArcSinh[x^2])/(
    2 Sqrt[1 + x^4])

    which when evaluated from 1 to infinity results in infinity

    Kovak on
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    KingAgamemnonKingAgamemnon Registered User regular
    edited May 2008
    Kovak wrote: »
    That doesn't make fucking sense how can something be finite in volume but infinite in surface area this is fucking bullshit.

    Put very simply, the function 1/x is rotated around the x-axis, giving us a horn shape. Normally 1/x has an asymptote (a singularity on the graph, usually somewhere where you've divided by 0) at 0, but Gabriel's horn has intervals that start at x>=1 it is effectively cut off from the region of the graph where it starts "stretching" to infinity (this would have been at x=0).

    Well, that roughly explains the finite volume. As far as infinite surface area, I don't quite remember.

    I do know that the derivative of an anti-derivative (i.e. volume) is surface area. Possible that using the fundamental theorem of calculus the derivative of int(1/x) with interval [1,inf) is infinity.

    the math just kinda says it does

    but to try to explain in plain words


    The volume if you imagine the small end gets smaller and smaller till eventually an addition of volume is not really adding anyhting

    The limit of the extra volume approaches 0. However, the surface area that provides that volume does not go to 0.

    I can post the math I guess.

    You kind of repeated the question in that second to last sentence there. No biggie, you did explain the whole small end gets smaller business that I failed to.

    KingAgamemnon on
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    KingAgamemnonKingAgamemnon Registered User regular
    edited May 2008
    Yeah, that math is kosher, but it doesn't help explain the "why."

    KingAgamemnon on
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    musanmanmusanman Registered User regular
    edited May 2008
    musanman wrote: »
    what's up with zero factorial equaling 1

    I mean, that's bullshit.

    also I know like 3 proofs for it I don't care what the maths say

    It has something to do with a special case of the Zeta Function

    Kind of complicated, so unless you take some upper level math courses, it is just defined as 1.

    you can do it using simple algebra, I know the proofs I've taken those classes

    I DISAGREE

    musanman on
    sic2sig.jpg
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    KingAgamemnonKingAgamemnon Registered User regular
    edited May 2008
    I amended it to the Gamma Function, do you still disagree? I'm not wrong in this case.

    KingAgamemnon on
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    KovakKovak did a lot of drugs married cher?Registered User regular
    edited May 2008
    Kovak wrote: »
    That doesn't make fucking sense how can something be finite in volume but infinite in surface area this is fucking bullshit.

    Put very simply, the function 1/x is rotated around the x-axis, giving us a horn shape. Normally 1/x has an asymptote (a singularity on the graph, usually somewhere where you've divided by 0) at 0, but Gabriel's horn has intervals that start at x>=1 it is effectively cut off from the region of the graph where it starts "stretching" to infinity (this would have been at x=0).

    Well, that roughly explains the finite volume. As far as infinite surface area, I don't quite remember.

    I do know that the derivative of an anti-derivative (i.e. volume) is surface area. Possible that using the fundamental theorem of calculus the derivative of int(1/x) with interval [1,inf) is infinity.

    the math just kinda says it does

    but to try to explain in plain words


    The volume if you imagine the small end gets smaller and smaller till eventually an addition of volume is not really adding anyhting

    The limit of the extra volume approaches 0. However, the surface area that provides that volume does not go to 0.

    I can post the math I guess.

    You kind of repeated the question in that second to last sentence there. No biggie, you did explain the whole small end gets smaller business that I failed to.

    For those still kinda confused I thought of a much better way to explain it

    if you think of the horn as a whole bunch of rings, placed right next to each other.

    Like

    ))))))

    the horn starts off with the cring radius being 1. This is the largest it ever is. The rings keep getting smaller and smaller until there is basically no "interior" they are no longer contributing to the volume of the object. However, despite being solid and having no interior. They still have an exterior which continues to add on area to the outside of the object.

    Kovak on
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    KovakKovak did a lot of drugs married cher?Registered User regular
    edited May 2008
    Wikipedia explains it far better than I do.
    A non-symbolic way of saying the same thing is the following: to "paint" the surface of the horn does indeed require an infinite surface area of paint, so that the sense in which it is infinite is as a two-dimensional substance. But to "paint" the surface by filling the horn with paint is to obscure it by a three-dimensional object, so the sense in which the amount of paint is finite is as a three-dimensional substance. The paradox arises because real paint is not two-dimensional, and in fact has a discrete thickness, so that painting the surface actually requires an infinite three-dimensional quantity. However, when the horn is filled with paint it is not the outside but the inside surface that is painted. To paint the inside surface of the horn with a layer of paint having a discrete thickness is impossible; once the horn becomes too narrow the paint will not fit. In fact, it is also impossible to fill the horn with such paint, so that in both cases, only finite extent of the horn is covered and the paradox vanishes.

    Kovak on
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    musanmanmusanman Registered User regular
    edited May 2008
    I amended it to the Gamma Function, do you still disagree? I'm not wrong in this case.

    I don't think you understand my complaint.

    I am not disagreeing with the mathematics of 0! = 1. There is no doubt in my mind, as I can prove it using sound math logic and even argue for the point of 0! = 1.

    All of the math background and experience with algebra will not convince me. You must argue this point using no mathematics for the conversation to be interesting.

    musanman on
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    yourclothesyourclothes __BANNED USERS regular
    edited May 2008
    duh duh duh

    yourclothes on
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    KovakKovak did a lot of drugs married cher?Registered User regular
    edited May 2008
    okay

    N!

    factorial counts how many ways you can line up N distinct objects

    You know like you have 3 objects

    for your first slot

    you have 3 options, then one is taken so you have 2 options, then there is one left so you have 1 option

    3*2*1

    Now how many ways do you have to line up 0 objects

    1

    1 ways

    Kovak on
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    yourclothesyourclothes __BANNED USERS regular
    edited May 2008
    whaaat

    yourclothes on
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