Hatrack River Forum: How do i determine average probability?

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Posted by Blayne Bradley (Member # 8565) on :

Say I roll 20 d6's, what the "average" number I am likely to get? The Monster manual lists the average hitpoints for monsters but lets say I want to increase its HD or decrease it, how do i recalculate the average?

Posted by King of Men (Member # 6684) on :

If you don't know by now how to calculate an expectation value, you might as well give up on programming and go be a plumber or something. Come on, dude, this is first-year stuff. (First year of high school, that is.) Write a program to simulate it, you might learn something.

Posted by fugu13 (Member # 2859) on :

The average number you are likely to get for 20 die rolls is just 20 times the average number you are likely to get for one die roll, which is the value of each possible roll times the probability of that roll.

So, for one die roll the average is:

1/6 + 2/6 + 3/6 + 4/6 + 5/6 + 6/6 = 3.5

Alternatively, you could note that there are three pairs of numbers on the die that each add up to 7, therefore the average must be 3.5

So, the average number you will get for 20 die rolls is 70.

Posted by King of Men (Member # 6684) on :

I don't think you're doing anyone any favours by explaining this truly elementary stuff, fugu.

Posted by fugu13 (Member # 2859) on :

Eh, even without really basic math like this he could end up being an okay member of an application programming team. Not a game programmer, certainly.

Posted by Blayne Bradley (Member # 8565) on :

quote:
Originally posted by King of Men:
I don't think you're doing anyone any favours by explaining this truly elementary stuff, fugu.

Even if it is elementary stuff I haven't had a statistics class to deal with probability in roughly 4 years. Its math, not algorithm design.

Posted by King of Men (Member # 6684) on :

Statistics? Dude, this isn't statistics, this is counting on yer dang fingers. This is two steps up from plain multiplication. Next you'll tell me you use a calculator for 7*8 on the grounds that you haven't studied multiplication in ten years. If you can't retain this much information from that class four years ago, you might as well give up on classes altogether; they're not doing you any good.

Posted by BlackBlade (Member # 8376) on :

Don't be so hard on him KOM. Blayne if you really care about programming though, you're going to have to take some extra time out of your day to understand basic math. Maybe retake college algebra even if it doesn't go towards your major.

Posted by Blayne Bradley (Member # 8565) on :

quote:
Originally posted by King of Men:
Statistics? Dude, this isn't statistics, this is counting on yer dang fingers. This is two steps up from plain multiplication. Next you'll tell me you use a calculator for 7*8 on the grounds that you haven't studied multiplication in ten years. If you can't retain this much information from that class four years ago, you might as well give up on classes altogether; they're not doing you any good.

I actually never learned my multiplication tables.

To clarify, I know MOST of them by now through day-to-day operations.But if Im at my computer, I use my calculator out of laziness.

Posted by King of Men (Member # 6684) on :

*Throws hands in the air, rolls eyes*

Really now. I must say my sympathy for your father is increasing with your every post.

Posted by The White Whale (Member # 6594) on :

It takes very little time to learn to do simple multiplication in your head, and from that point on you save time and energy every time you see 7x8. You should see that, have the answer, and move on without blinking an eye.

You're attending school, now, right? I know most of my math and computer classes didn't allow calculators in the tests. Sure, the math was relatively simple, but you were absolutely expected to be able to do it without a calculator without a problem.

Posted by scifibum (Member # 7625) on :

quote:
Originally posted by Blayne Bradley:

quote:
Originally posted by King of Men:
I don't think you're doing anyone any favours by explaining this truly elementary stuff, fugu.
Even if it is elementary stuff I haven't had a statistics class to deal with probability in roughly 4 years. Its math, not algorithm design.

How would you write an algorithm to answer the question you started the thread with?

Posted by BlackBlade (Member # 8376) on :

quote:
Originally posted by Blayne Bradley:

quote:
Originally posted by King of Men:
Statistics? Dude, this isn't statistics, this is counting on yer dang fingers. This is two steps up from plain multiplication. Next you'll tell me you use a calculator for 7*8 on the grounds that you haven't studied multiplication in ten years. If you can't retain this much information from that class four years ago, you might as well give up on classes altogether; they're not doing you any good.
I actually never learned my multiplication tables.

To clarify, I know MOST of them by now through day-to-day operations.But if Im at my computer, I use my calculator out of laziness.

Nobody learns their multiplication tables without making a concerted effort to do so. It's extremely obnoxious to learn them, but I've yet to hear anybody memorize them and complain that they did not provide a return on their investment.

If you sit down and memorize at least your 2-12 tables you will find thousands if not millions of calculations you make the rest of your life will be much easier.

You probably won't take my advice Blayne, but it's there for you anyway.

Posted by King of Men (Member # 6684) on :

code:

10 GOSUB POST_ON_HATRACK
20 GOSUB WHINGE_ABOUT_HOW_HARD_STUFF_IS
30 GOSUB COMPLAIN_ABOUT_OTHER_PEOPLE
40 GOTO 10

Posted by King of Men (Member # 6684) on :

What have you got against the one-times table, BlackBlade? [Big Grin]

Posted by BlackBlade (Member # 8376) on :

quote:
Originally posted by King of Men:
What have you got against the one-times table, BlackBlade?

Everyone knows I am, if nothing else, a two timer.

In third grade my mom made me sit in a chair and start memorizing those freaking tables and I remember the laminated chart she gave me had the one table. The deal was every week I had to memorize three tables. I tried to pawn the one table off as one of those three, but no dice. I don't think my parents repeated the process with any of my 4 younger siblings, or heck my older sister for that matter.

Posted by King of Men (Member # 6684) on :

Didn't you learn it in school?

Posted by BlackBlade (Member # 8376) on :

quote:
Originally posted by King of Men:
Didn't you learn it in school?

I don't recall there being a concerted effort to learn them in my two schools growing up. But with all the multiplication you had to accomplish through rote repetition you would have been royally screwed if you didn't memorize them.

Posted by Lisa (Member # 8384) on :

Blayne, just guess. If you guess a sufficiently large number of times, you're bound to get the answer correct.

Posted by HollowEarth (Member # 2586) on :

quote:
Originally posted by scifibum:
How would you write an algorithm to answer the question you started the thread with?

in matlab:

code:

r = ceil(6.*rand(20,1e4));
mean_of_20_d6 = mean(sum(r));

Basically, just generate many (above I used 10,000) groups of 20 random integers between 1 and 6, then add up each group and take the mean of the entire ensemble.

Incidently, I found 70.056 when I ran the above.

The outcome of this kind of experiment is precisely what we mean when we ask this kind of question, even if in general there are better ways to find the answer.

Posted by scifibum (Member # 7625) on :

HollowEarth: I wasn't really asking because I wanted to know. I was asking because I wanted Blayne to think about it.

Simulating the die rolls may be a perfectly valid way to approximate the answer, and it's good to know how to do that, but I did want to point out that it might often be easier and more efficient to know how to use mathematical functions to calculate that sort of thing than it is to simulate the experiment.

Matlab apparently makes it quite easy either way.

Posted by Blayne Bradley (Member # 8565) on :

Yeah, Hollow, KoM, I didn't want to know the CODE to simulate the die roll as frankly there's billions of such things on the net, I wanted to know the theory behind figuring out averages so I could oddball in my head the average rather then thinking the average was always roughly half of the die rolled.

Posted by swbarnes2 (Member # 10225) on :

The "theory" is that since all the dice rolls are independant of each other, you can find the average for one, and just multiply for the number of dice you've got.

Posted by King of Men (Member # 6684) on :

I know. Asking about the code might have been halfway reasonable. Not knowing the theory is epic-level ignorance (*). That's the point at which you should realise that you should drop what you're doing and go study po-mo feminism instead, where being utterly ignorant of your subject isn't a handicap.

(*) Or so I thought until you admitted to not knowing the multiplication tables.

Posted by Paul Goldner (Member # 1910) on :

Seriously, Blayne, there's no way you can have a successful career in anything using mathematics if you don't know how to do averages at this point in your life. What you're asking for help on is stuff I had mastered before moving to middle school, and never had to think about it again. Its time to change career plans... or devote about 12 hours a day, every day, to catching up in your education.

Posted by Blayne Bradley (Member # 8565) on :

quote:
Originally posted by King of Men:
I know. Asking about the code might have been halfway reasonable. Not knowing the theory is epic-level ignorance (*). That's the point at which you should realise that you should drop what you're doing and go study po-mo feminism instead, where being utterly ignorant of your subject isn't a handicap.

(*) Or so I thought until you admitted to not knowing the multiplication tables.

Yeah keep insulting the one guy who genuinely wants you to survive attacks from Britannia, keep doing that and see where it goes.

Posted by Blayne Bradley (Member # 8565) on :

quote:
Originally posted by Paul Goldner:
Seriously, Blayne, there's no way you can have a successful career in anything using mathematics if you don't know how to do averages at this point in your life. What you're asking for help on is stuff I had mastered before moving to middle school, and never had to think about it again. Its time to change career plans... or devote about 12 hours a day, every day, to catching up in your education.

I hardly remember even so much as a single day of my youth in either high school or elementary school, its all frankly a blurr I retained I think the majority of my skills but I don't remember so much as a single day of it.

For the record I passed Calculus with 80% which to my knowledge is pretty much a requirement for programming physics or anything involving rates of change so obviously I'm not getting everything wrong.

Posted by Paul Goldner (Member # 1910) on :

Passing a class and understanding the material are different things.

You don't understand very simple math.

Posted by Tstorm (Member # 1871) on :

I remember learning multiplication tables starting in second grade. Some of them, we learned the pattern, and some of them, we learned by singing to a nursery rhyme. It's amazing that I can still remember the song to which we learned the 4 table.

I must admit to being flabbergasted that some people never learned the multiplication tables in school. (As in, it was never taught, not that they 'decided not to learn them'.) Seriously, what else should be taught in the elementary levels, math-wise?

Posted by Blayne Bradley (Member # 8565) on :

quote:
Originally posted by Paul Goldner:
Passing a class and understanding the material are different things.

You don't understand very simple math.

And I perfectly understand college level calculus up to related rates, we didnt go into anti derivatives or integration but I roughly know what those are and understand pretty well everything before that.

Passing a class is different from understanding it but passing WELL is a far cry removed from just passing and requires understanding the material.

Posted by TomDavidson (Member # 124) on :

What's "passing well?" Is that a B+?

Posted by Blayne Bradley (Member # 8565) on :

I'm Canadian from Quebec, its whatever a little above 80% is. 60% is pass.

Posted by King of Men (Member # 6684) on :

You're wrong. 80% is what the lib'ral arts students get for their piece of paper that qualifies them to ask whether you want fries with that. A good pass is somewhere in the region of 95%.

Posted by Blayne Bradley (Member # 8565) on :

quote:
Originally posted by King of Men:
You're wrong. 80% is what the lib'ral arts students get for their piece of paper that qualifies them to ask whether you want fries with that. A good pass is somewhere in the region of 95%.

Seriously dude I already got an authority figure who acts like that and who berates me for underachieving, whats your problem? At least with my professor I know he genuinely cares about me succeeding on a personal level, whats with you? Whats your excuse? Surely you remember back in Crusader Kings helping me with linked lists, I understood it in the end after the roughly 4 hours of what was probably frustrating for both of us, but hey I got it in the end.

Posted by King of Men (Member # 6684) on :

I remember that, yes. I also remember thinking you were being kind of slow. I understand it better now. Brains atrophy when not used, like any other muscle.

I am disgusted by ignorance wherever I find it, whether or not I care about its possessor's fate. Seriously. There is absolutely no excuse for this. It's as bad as creationism, without even the thin excuse of brainwashing; you're just lazy. You're letting the side down. The one advantage rational people have in presenting truth, and geeks have in getting the girls, is that we are more intelligent than the competition. And you can't multiply single-digit numbers! There are chimpanzees that can memorise this kind of thing. The likes of Ron and Lisa can do it.

Posted by Blayne Bradley (Member # 8565) on :

I think your misunderstanding, I can multiply X and Y, I just can't do it for some numbers without having to do it by writing it down and "carrying the one". And yes I can do single digit numbers your misunderstand.

Posted by rivka (Member # 4859) on :

KoM, that was rude and inappropriate. No personal attacks.

[Razz]

Posted by Belle (Member # 2314) on :

You know what's really sad? I have an English degree and I can do more math in my head than Blayne.

In all seriousness, you do need to think long and hard about what you're planning to do if these mathematical concepts don't come easily to you. It's not so much that you haven't memorized tables (which every 3rd grader should know) but a lack of ability to apply any mathematical knowledge that you are exhibiting here.

Unless, of course you're just yanking everyone's chain and being obnoxious.

Posted by King of Men (Member # 6684) on :

quote:
Originally posted by Blayne Bradley:
I think your misunderstanding, I can multiply X and Y, I just can't do it for some numbers without having to do it by writing it down and "carrying the one". And yes I can do single digit numbers your misunderstand.

Mmph. That's something, then. There's still the issue of not knowing how to calculate an expectation value. Really, now.

Posted by Rappin' Ronnie Reagan (Member # 5626) on :

If people would stop answering Blayne's questions whenever he posts this kind of thread maybe he'd stop asking and figure the answers out himself.

Posted by King of Men (Member # 6684) on :

That's what I said, but fugu wouldn't listen to me.

Posted by fugu13 (Member # 2859) on :

I was typing well before you said it, but true, I would have disregarded anyways. He's not going to look it up even if not told, and I pointed out a few different ways of doing things (so hopefully he'll remember one of them in the future).

Posted by BlackBlade (Member # 8376) on :

quote:
Originally posted by Rappin' Ronnie Reagan:
If people would stop answering Blayne's questions whenever he posts this kind of thread maybe he'd stop asking and figure the answers out himself.

It does not take much effort typically to help Blayne out in these sorts of things. It's getting him to accept one legitimate criticism of Chinese or Russian government that is of epic difficulty.

Posted by MrSquicky (Member # 1802) on :

Blayne's problem is not really that he doesn't know basic things. That's more of a symptom of his basic problem, which is that he is unwilling to do things, every very easy things, for himself.

When you give him the answers to things like this, you are hurting, not helping him.

Right now, he's a terrible programmer, ignorant of both basic coding and debugging techniques and fundamentals on which elegant, efficient code rests. He can't figure out the answers to extremely simple programming problems using a google search. And he's this way in part because there are people on Hatrack who don't seem to care about him that are willing to answer his questions for him. But at the level he's at now, especially with his attitude and lack of a decent self-improvement skill set, he's never going to be able to get or at least hold a decent programming job.

And, Jebus help me, I actually think he might be smart enough to do so. He just needs to grow up an awful lot.

Posted by Blayne Bradley (Member # 8565) on :

quote:
Originally posted by fugu13:
I was typing well before you said it, but true, I would have disregarded anyways. He's not going to look it up even if not told, and I pointed out a few different ways of doing things (so hopefully he'll remember one of them in the future).

I considered averages as "add up all the numbers and divide by the total" which incidentally is 3.5, I just didn't really believe it. So I came for confirmation..... I just realized ust this second is essnetially what 1/6 + 2/6 + 3/6 + ... + 6/6 is. *facepalm*

Posted by Blayne Bradley (Member # 8565) on :

Now to figure out an easy way to add up all of the positive integers of n for larger numbers like a d100 as adding up 100 + 99 + 98... will probably take a while.

Whats the version of Factorial called where they're adding it up to find the sum and not finding the product?

just the name, I dont need a demonstration.

Posted by Strider (Member # 1807) on :

quote:
You're wrong. 80% is what the lib'ral arts students get for their piece of paper that qualifies them to ask whether you want fries with that. A good pass is somewhere in the region of 95%.

actually, i think it's the other way around.

I was always really frustrated with my liberal arts friends who were earning As really easily, in classes I could've earned those kinds of grades in as well. Meanwhile I was struggling in extremely hard science and programming classes, earning lower grades and doing much more work.

Posted by King of Men (Member # 6684) on :

I'm aware that they get easy As in their own courses. I meant that in the one math course they're required to take, they get 80%.

Blayne, that's a classic case of why you should pay attention in class. That problem is famous.

Posted by Strider (Member # 1807) on :

true. and even that one math course was so simplified for their major. And here I was banging my head against the wall in differential equations and linear algebra.

Posted by Sean Monahan (Member # 9334) on :

quote:
Originally posted by Blayne Bradley:
Now to figure out an easy way to add up all of the positive integers of n for larger numbers like a d100 as adding up 100 + 99 + 98... will probably take a while.

Whats the version of Factorial called where they're adding it up to find the sum and not finding the product?

just the name, I dont need a demonstration.

Here's a hint: Carl Gauss came up with a formula for this when he was in grade school, though the story may be apocryphal.

Posted by fugu13 (Member # 2859) on :

Blayne: There isn't a name, and that you haven't figured this one out shows that you need to think much harder about what people write.

quote:
And he's this way in part because there are people on Hatrack who don't seem to care about him that are willing to answer his questions for him.

I think this is nonsense. While waiting and seeing if someone realizes how to research things works for certain very motivated, very intelligent students like many on hatrack, it is fairly clear there are issues Blayne has with picking up techniques like that on his own, combined with teachers of less than full competence who fail at teaching those techniques. I believe he is better served by being shown a variety of techniques to learn from. After all, people have long learned how to answer questions like this one when they had no internet, and frequently no way to "look up" the way to do the problem other than being shown by a teacher.

Posted by Lisa (Member # 8384) on :

quote:
Originally posted by Blayne Bradley:
Now to figure out an easy way to add up all of the positive integers of n for larger numbers like a d100 as adding up 100 + 99 + 98... will probably take a while.

Whats the version of Factorial called where they're adding it up to find the sum and not finding the product?

just the name, I dont need a demonstration.

It doesn't have a name. But it has a simple solution.

Posted by Xavier (Member # 405) on :

In my Advanced Algorithm's class I recently had to find out what that is called, when I realized the number of iterations the algorithm I had designed was a sequence of n+(n-1)+(n-2)+...+1.

It's called an Arithmetic Series. The simplest one, with d=1.

[Edit: Formula removed for pedagogic reasons]

I found that out in a few minutes of googling when I encountered it. I knew it was a common problem I'd encountered in school (6th grade I think), but couldn't remember the name of it, and so it wasn't especially easy for me to find. I considered, momentarily, asking hatrackers what the name of the problem was in a Mayfly. I guess now I'm awfully glad I didn't.

Now I'm as big a critic of Blayne as most of you guys normally, but I feel to some extent you're being a bit harsh here. We just had a thread like last week where a few of the smartest members of hatrack couldn't immediately come up with expected value of dice roll with n sides. They weren't scorned or mocked for it. Just because you've encountered something before in your studies doesn't mean you'll be able to recall the answer immediately.

[ June 05, 2009, 09:00 AM: Message edited by: Xavier ]

Posted by TomDavidson (Member # 124) on :

Blayne, I have noticed that you have a very linear mind. You look at a problem like "how do I sum all the positive integers of n" and you immediately look at the obvious method -- adding up the positive integers, one by one. And then you stop.

But let us instead imagine that this is a puzzle of some sort, one for which the walkthrough has not yet been posted on the Internet.

So let's look at what happens when you add just two numbers of n. If they're just two adjacent numbers in sequence, like 3 and 4, it doesn't tell us much. But perhaps there is a combination of numbers we CAN add that tells us more.

Perhaps we can think of n algorithmically, as if it were a set of items we had to access through repeated trips. Let's say that, on each trip, we have space in our imaginary car for just two numbers.

Is there any approach we can take, pulling out just two numbers each time, that tells us something revealing about this set? If just pulling out sequential numbers doesn't help us, perhaps we could look at the outer bounds of the set for clues...?

Posted by TomDavidson (Member # 124) on :

Bah. Phil just gave you the answer.

Posted by Xavier (Member # 405) on :

I could delete the formula, but I think it's fairly unreasonable to have expected Blayne to reason it out on his own. Some people can do that, with effort, but I think less of you could than you may believe. It's easy to remember something you learned when you were young and pretend that you would have discovered it on your own.

Posted by TomDavidson (Member # 124) on :

I agree with you that it's not necessarily harmful to Blayne to tell him the occasional answer.

But I DO think that, in this specific case, helping him to derive this algorithm on his own would be far, far more valuable to his future career than just about anything else we could do for him. I think it's really important that he, as a prospective programmer, learn to think about methods of accessing a set -- and why those methods might matter.

Posted by Samprimary (Member # 8561) on :

I'm amazed people here still think there's anything they can do to 'help' him be a successful programmer.

Posted by Xavier (Member # 405) on :

quote:
Originally posted by Samprimary:
I'm amazed people here still think there's anything they can do to 'help' him be a successful programmer.

I guess that depends on your definition of 'successful'. I've worked with many programmers who don't have natural talent or even possess a working knowledge of mathematic concepts.

They are "successful" in that they are pulling in very decent paychecks and steady employment. My name for them in my head is the "C-students", though obviously I have no idea what grades they got in their programming classes. It's more that I equate them to the students I encountered as an undergrad, who could struggle their way through the classes (often with help of brighter students) while a few (like me) breezed by fairly effortlessly.

I've found that in a reasonably sized application programming shop, they comprise at least 75-85% of the development staff. They aren't who you'd turn to for elegant or complex solutions, but they can write basic business / application logic and follow a code-by-numbers approach. So long as you have a few "A-students" on staff who can direct them, they are useful enough.

Posted by Scott R (Member # 567) on :

WTF, people?

Knock it off with the personal insults.

Posted by twinky (Member # 693) on :

I forgot how to calculate expected values for n-sided dice in that RPG thread just a few weeks ago, and I've taken statistics at the graduate level.

IMO, it's more important to remember how to apply something correctly than it is to remember how to do it. You can look up a formula, but if you aren't cognizant of the basic assumptions on which that formula rests... well, "garbage in, garbage out."

Posted by Tresopax (Member # 1063) on :

I'm amazed that certain people seem to justify being a jerk to Blayne in this thread on the grounds that it is somehow going to help him. I understand the reasoning for not giving him an answer to his question, but that's no justification for claiming he's better off abandoning his chosen profession to become a plumber, or something like that.

---

As a side note, I'd add that I think in the business world the ability to go find an answer is often more important than the ability to actually think it up oneself.

Posted by Blayne Bradley (Member # 8565) on :

Luckily for me and you Xavier is my internet cutout on me last night and in a hilarious case of giggles I refused to try solving it by resetting the router which 15 hours later was the only way I could fix it, so I have no idea what he wrote.

Posted by Xavier (Member # 405) on :

I'm having trouble parsing that sentence. I guess I'll just go with "yes, that is lucky for me" and move along [Wink]

Posted by TomDavidson (Member # 124) on :

*grin* Well, good.
In all seriousness, look at what I wrote up there and think of it as a puzzle. If you're going to add a set of sequential numbers in as few trips as possible, and you can only pull out two numbers per trip, what two numbers can you pull out that might tell you everything you need to know?

Posted by Teshi (Member # 5024) on :

Sometimes it helps to break down problems into small pieces, or perhaps even rephrase the problem to yourself. As it is, I have no idea how to do what you are describing because I don't understand the question.

And Blayne, you're doing fine.

Posted by Samprimary (Member # 8561) on :

quote:
Originally posted by Tresopax:
I understand the reasoning for not giving him an answer to his question, but that's no justification for claiming he's better off abandoning his chosen profession to become a plumber, or something like that.

The frustration here is based on heavily repeated trends that cause skepticism about the realistic potential for Blayne to be a real programmer. At some point people are going to start pointing out that he gives no confidence whatsoever to a public audience that he's doing anything but fooling himself and that he needs to get real.

I mean, not that it's as serious, but imagine if I repeatedly boasted about how my chosen career was to be a surgeon and then for the next few years I kept making threads asking things like 'what is triage guys??'

whattamigonnaget

Posted by rivka (Member # 4859) on :

Hopefully more common courtesy than you have shown.

Posted by Scott R (Member # 567) on :

quote:
but imagine if I repeatedly boasted about how my chosen career was to be a surgeon and then for the next few years I kept making threads asking things like 'what is triage guys??'

whattamigonnaget

Well, civilized adults will likely ignore you.

Posted by Blayne Bradley (Member # 8565) on :

quote:
Originally posted by TomDavidson:
Blayne, I have noticed that you have a very linear mind. You look at a problem like "how do I sum all the positive integers of n" and you immediately look at the obvious method -- adding up the positive integers, one by one. And then you stop.

But let us instead imagine that this is a puzzle of some sort, one for which the walkthrough has not yet been posted on the Internet.

So let's look at what happens when you add just two numbers of n. If they're just two adjacent numbers in sequence, like 3 and 4, it doesn't tell us much. But perhaps there is a combination of numbers we CAN add that tells us more.

Perhaps we can think of n algorithmically, as if it were a set of items we had to access through repeated trips. Let's say that, on each trip, we have space in our imaginary car for just two numbers.

Is there any approach we can take, pulling out just two numbers each time, that tells us something revealing about this set? If just pulling out sequential numbers doesn't help us, perhaps we could look at the outer bounds of the set for clues...?

1 and 1000, 2 and 999, 3 and 998 ... etc? They add up to 1001, since they're pairs it means there are 500 said pairs, 500 * 1001 gives the total.

My brother points out that in calculus a discreet rate of change is f(x+1) - f(x) which is almost like the derivative, so n(n+1)/2 = all the numbers in N, though he skipped all of the in his words "the boring details" hes a Math major in McGill.

For an example of a d20

1 + 20 = 21 * 10 = 210 divide by 20 = 10.5 which fits with the by hand exmaple of average of a 1d6.

Posted by TomDavidson (Member # 124) on :

*applause*

Posted by scifibum (Member # 7625) on :

Nice, Blayne!

Posted by MrSquicky (Member # 1802) on :

quote:
While waiting and seeing if someone realizes how to research things works for certain very motivated, very intelligent students like many on hatrack, it is fairly clear there are issues Blayne has with picking up techniques like that on his own, combined with teachers of less than full competence who fail at teaching those techniques.

I'm not saying let him flounder around without giving him any help at all. I'm saying stop just giving him the answers.

If you want to help, help him get to those answers with effort on his own. I've actually tried to do this with Blayne (with him whining the whole time that I wouldn't just give him the answer) just to have people come in and give him the answer, which hurts Blayne and ruins my effort.

Blayne needs to learn how to figure these things on his own, but there are two things to overcome there. One, as you noted, is that he seems like that he might be poorly served in the instruction he has gotten so far. But the second and more damning problem he has is that he really doesn't want to learn how to do things for himself.

Giving him the answer doesn't help him. As I noted, it actually hurts both of these.

Posted by Samprimary (Member # 8561) on :

quote:
Originally posted by Scott R:
Well, civilized adults will likely ignore you.

Sure, for the first 30-40 threads.

Keep in mind that this is an observation of appearances and thread making habits, not actual potential to be a programmer, which I don't bother to guess at.

I'm not the one telling anybody to stop trying to be a programmer and go be a plumber just because of thread habits! Although these days if you could drop programming and pick up being a plumber that may entail a net increase in potential wages.

I mean, damn, son. Plumbers make a mint around here.

Posted by The Pixiest (Member # 1863) on :

Samp: Yeah, but it's a crappy job.

Posted by Blayne Bradley (Member # 8565) on :

quote:

TARRASQUE
Colossal Magical Beast
Hit Dice: 48d10+594 (858 hp)
Initiative: +7
Speed: 20 ft. (4 squares)
Armor Class: 35 (–8 size, +3 Dex, +30
natural), touch 5, flat-footed 32
Base Attack/Grapple: +48/+81
Attack: Bite +57 melee (4d8+17/18–20/×3)
Full Attack: Bite +57 melee (4d8+17/
18–20/×3) and 2 horns +52 melee
(1d10+8) and 2 claws +52 melee
(1d12+8) and tail slap +52 melee
(3d8+8)
Space/Reach: 30 ft./20 ft.
Special Attacks: Augmented critical,
frightful presence, improved grab, rush, swallow
whole
Special Qualities: Carapace, damage reduction
15/epic, immunity to fire, poison, disease, energy
drain, and ability damage, regeneration 40, scent,
spell resistance 32
Saves: Fort +38, Ref +29, Will +20
Abilities: Str 45, Dex 16, Con 35,
Int 3, Wis 14, Cha 14
Skills: Listen +17, Search +9, Spot
+17, Survival +14 (+16 following
tracks)
Feats: Alertness, Awesome Blow, Blind-Fight, Cleave, Combat
Reflexes, Dodge, Great Cleave, Improved Bull Rush,
Improved Initiative, Iron Will, Power Attack, Toughness (6)
Environment: Any
Organization: Solitary
Challenge Rating: 20
Treasure: None
Alignment: Always neutral
Advancement: 49+ HD (Colossal)
Level Adjustment: —

So average of 10 is 5.5, * 48 is 264, + 594 is 858. So it works!

Posted by Samprimary (Member # 8561) on :

I'm probably biased in this regard. I would rather plumb than program. I actually abandoned programming and network administration classes spontaneously a number of years ago because I was starting to realize that even if I was good at it, I hated the work and the torpor-like feeling of gajillions of hours in front of a screen.

Posted by Belle (Member # 2314) on :

I should point out, as someone who helped run a plumbing company, that plumbing is not exactly devoid of math. To be a really successful plumber, you need to own your own business, and that requires understanding of accounting. Even to just do the job, you need more than just basic calculation skills.

Posted by fugu13 (Member # 2859) on :

I'd like to note I mentioned the technique of pairing the numbers at each end up in the second reply of this thread, hence my suggestion that Blayne read more closely [Wink]

But yes, it is entirely possible for Blayne to be a programmer with no particular mathematical chops. However, Blayne, if you want to be a game programmer, I strongly suggest you take at least an upper level matrix/linear algebra course in the math department. Only with that level of understanding under your belt will you be able to be a game programmer of the sort you seem interested in being.

Posted by King of Men (Member # 6684) on :

quote:
Originally posted by twinky:
I forgot how to calculate expected values for n-sided dice in that RPG thread just a few weeks ago, and I've taken statistics at the graduate level.

"Have attended classes" might be the more accurate formulation. This is not a support for Blayne's ignorance, it is an indictment of your 'graduate-level' classes.

quote:
IMO, it's more important to remember how to apply something correctly than it is to remember how to do it. You can look up a formula, but if you aren't cognizant of the basic assumptions on which that formula rests... well, "garbage in, garbage out."

I agree. But notice that Blayne hasn't got to the level of knowing what 'it' is, in the case of expectation values. Before you can apply X correctly, before you can even look up the procedure for X, you must at a minimum know that X exists!

Posted by Blayne Bradley (Member # 8565) on :

quote:
Originally posted by fugu13:
I'd like to note I mentioned the technique of pairing the numbers at each end up in the second reply of this thread, hence my suggestion that Blayne read more closely

But yes, it is entirely possible for Blayne to be a programmer with no particular mathematical chops. However, Blayne, if you want to be a game programmer, I strongly suggest you take at least an upper level matrix/linear algebra course in the math department. Only with that level of understanding under your belt will you be able to be a game programmer of the sort you seem interested in being.

I plan to see if its possible to take those courses during my first semester.

Posted by fugu13 (Member # 2859) on :

You will not have sufficient background to take an upper level matrix/linear algebra course in your first semester. That would be a long-term goal.

Heck, go ahead and link me to your university's course catalog and I'll tell you what the course options are that would be what you'd need to take.

Posted by Blayne Bradley (Member # 8565) on :

the prereq for linear is highschool 536 advanced math (which i have) I'm pretty sure but Ill try to find it.

Posted by King of Men (Member # 6684) on :

The prerequisite does not mean "attended this class", it means "understood these concepts".

Posted by twinky (Member # 693) on :

quote:
Originally posted by King of Men:

quote:
Originally posted by twinky:
I forgot how to calculate expected values for n-sided dice in that RPG thread just a few weeks ago, and I've taken statistics at the graduate level.
"Have attended classes" might be the more accurate formulation. This is not a support for Blayne's ignorance, it is an indictment of your 'graduate-level' classes.

That I don't recall a formula is hardly an indictment of the classes. That was part of my point. I know to check for pitfalls and make sure I'm avoiding them before I start doing any analysis, in case there's a watch-out I've forgotten about -- which is quite likely, considering the volume of other knowledge I've filled my head with since the time when I first learned about the concepts.

The other part of my point is that while I felt silly for having forgotten such a basic concept, I wasn't ridiculed and insulted in the way that Blayne has been here. Even if I'd started a thread saying "hey, I've forgotten how to calculate the expected value of rolling an n-sided die," I'm confident I wouldn't have been met with remotely the same level of scorn and ridicule that Blayne has been subjected to here.

quote:
Before you can apply X correctly, before you can even look up the procedure for X, you must at a minimum know that X exists!

So he came and asked the question. I'm not seeing the problem, beyond that Blayne comes and asks a lot of questions here rather than doing his own research. But he's hardly the only person to have done that here.

Posted by King of Men (Member # 6684) on :

quote:
That I don't recall a formula is hardly an indictment of the classes.

True, but people were dinging me for personal attacks.

quote:
The other part of my point is that while I felt silly for having forgotten such a basic concept, I wasn't ridiculed and insulted in the way that Blayne has been here.

You would have been if I'd been in that thread.

quote:
So he came and asked the question. I'm not seeing the problem.

The problem is that there is a minimum level of knowledge you must have before you can ask useful questions. Asking about expectation values is a bit like asking how to look things up in a dictionary, or how to read.

Posted by twinky (Member # 693) on :

quote:
Originally posted by King of Men:

quote:
That I don't recall a formula is hardly an indictment of the classes.
True, but people were dinging me for personal attacks.

quote:
The other part of my point is that while I felt silly for having forgotten such a basic concept, I wasn't ridiculed and insulted in the way that Blayne has been here.
You would have been if I'd been in that thread.

By you, sure. But that hardly equates to the volume of scorn we've seen here.

quote:
Originally posted by King of Men:

quote:
So he came and asked the question. I'm not seeing the problem.
The problem is that there is a minimum level of knowledge you must have before you can ask useful questions. Asking about expectation values is a bit like asking how to look things up in a dictionary, or how to read.

It isn't at all like either of those things. Those things are universal knowledge; even a seemingly basic concept like expectation values is actually fairly specialized knowledge when you compare it to the overall set of knowledge areas. It doesn't surprise me at all that Blayne either hasn't encountered it before or doesn't recall having encountered it before because it was a long time ago.

Posted by Xavier (Member # 405) on :

quote:
However, Blayne, if you want to be a game programmer, I strongly suggest you take at least an upper level matrix/linear algebra course in the math department.

It was required that each student do so in my Bachelor's program, as well as up to Calculus III (3 dimensional calculus).

I went as far as getting the minor, which was strongly encouraged. I'm glad my program was set up that way.

The absolutely best class for any programmer to take, in my opinion, is an upper level math class called "Abstract Algebra". It was the hardest class offered in the Mathematics major (according to my Math major friends), but it all came very naturally to me. Succeeding in studying the concepts of the class trained my brain to think in ways that improved my programming skills better than any computer science class I took, I believe.

Posted by MrSquicky (Member # 1802) on :

quote:
By you, sure. But that hardly equates to the volume of scorn we've seen here.

If you take KOM out, who here is heaping scorn on Blayne for not knowing expected value?

Posted by twinky (Member # 693) on :

Is it bad that I can predict your entire line of argument from your first leading question? [Razz]

Maybe we've been hanging out in the same threads for too long. <3

Posted by MrSquicky (Member # 1802) on :

I am seeing this "Everyone is being mean to Blayne" vibe again, but from what I can tell, it's KOM, who is just about always a jerk, Samp, who seems to aspire to almost always being a jerk, but is giving Blayne problems for his posting history, not about this particular problem, and me, who is saying mean, but true things about Blayne that are not really about expected values.

So, where are you seeing this scorn heaped on Blayne for not knowing expected values by anyone other than KOM?

I mean, you want to have a "Don't say anything mean to Blayne" complaint, go right ahead, but I don't think the tack you are taking really matches up with what actually happened on this thread.

Posted by fugu13 (Member # 2859) on :

I don't mean an introductory linear algebra course. I said advanced. You've talked about things like programming game engines. That's very different from scripting an existing game system (which is also an important part of game programming, but it doesn't sound like what you want to do). Programming a modern game engine well requires an advanced undergraduate/beginning graduate understanding of linear algebra (not that this has to be arrived at through classes, but that's easiest for most people).

Posted by King of Men (Member # 6684) on :

I'd like to point out that it also requires a freshman-highschool level of understanding probability, which Blayne doesn't seem to have. First things first.

Posted by twinky (Member # 693) on :

quote:
Originally posted by MrSquicky:
I don't think the tack you are taking really matches up with what actually happened on this thread.

There was not one comment about the expected value mix-ups by me and others in the previous thread. Here we have two pages in not very much time. I think the main difference between this thread and the other one is that this one was started by Blayne.

I'm also not just talking about explicitly insulting comments.

Posted by twinky (Member # 693) on :

quote:
Originally posted by King of Men:
I'd like to point out that it also requires a freshman-highschool level of understanding probability, which Blayne doesn't seem to have. First things first.

In law, I'm told that there is a particular misapplication of statistics so common that it actually has a name: "the prosecutor's fallacy." If everyone coming out of high school had this "freshman-highschool level of understanding probability" that you're talking about, the prosecutor's fallacy wouldn't exist, but I think the reality is that people who understand these concepts are in fact not all that common.

Perhaps the prosecutor's fallacy never shows up in Norwegian courts, but I doubt that. I suspect it's more likely that your view of what constitutes a basic concept in statistics or math is coloured by your education level.

Posted by MrSquicky (Member # 1802) on :

quote:
There was not one comment about the expected value mix-ups by me and others in the previous thread. Here we have two pages in not very much time. I think the main difference between this thread and the other one is that this one was started by Blayne.

Well, that and the purpose of the thread. This is a thread where Blayne is explicitly asking for help, which is different from a slight mix up on something tangential to the thread it occurred in.

But yeah, I'd agree that this is a major difference. It seems to me that people here shouldn't be expected to react the exact same way to every poster.

For myself, if you asked for help with something like this, I'd just tell you. I wouldn't try to get you to figure out for yourself or try to get other people to not to just tell you. I treated Blayne differently because he's a very different person from you.

And, I'm not seeing all that much scorn for Blayne on this thread, except from people who give scorn to most all comers. There's not a high amount of respect for Blayne, but high amounts of respect isn't something that Blayne has earned.

---

What are you trying to accomplish with this, twinky? You know what I'm trying to do, but I'm not sure I see what you see coming out of your interactions here.

Posted by King of Men (Member # 6684) on :

The prosecutor's fallacy is basically misunderstanding (or not knowing, or misapplying) Bayes. Bayes is not exactly difficult, but in my experience it is not taught to high-school kids, either. Calculating expectation values is, or at least I was taught it there. Knowing how to take an average won't save you from the prosecutor's fallacy.

A further point is that Blayne is a gamer. Expectation values over random distributions show up all the time in games. He is apparently telling us he doesn't (or didn't) know how to figure out which of two swords does more damage on average! (This is, incidentally, the way I learned to calculate averages, some years before getting formal instruction in it.)

Posted by MrSquicky (Member # 1802) on :

quote:
I suspect it's more likely that your view of what constitutes a basic concept in statistics or math is coloured by your education level.

I think you're giving KOM credit for knowing a lot more about statistics than he's shown in the past. Based on his frequent mistakes about basic aspects of statistics, I doubt it's his education level that's coloring his comments.

Posted by twinky (Member # 693) on :

quote:
There's not a high amount of respect for Blayne, but high amounts of respect isn't something that Blayne has earned.

It's okay to treat Blayne disrespectfully because this disrespect has been earned? One would hope that there is a base level of respect afforded to non-trolls.

quote:
What are you trying to accomplish with this, twinky? You know what I'm trying to do, but I'm not sure I see what you see coming out of your interactions here.

I initially posted to add to X's comment about the other thread. It sparked a discussion. I didn't have a motive, but here's what I think: this thread would have been much shorter if Tom's response had been in the first few replies, whether it came from him or someone else.

Posted by MrSquicky (Member # 1802) on :

quote:
It's okay to treat Blayne disrespectfully because this disrespect has been earned? One would hope that there is a base level of respect afforded to non-trolls.

I don't know about that. I didn't say anything about disrespect, but rather high amounts of respect. These are two very different things.

---

Yeah, I get that that was your initial reason. What is your motive for this line of discussion?

---

I'm not sure what comment of Tom's you are talking about. Is it the one at the top of this page?

Posted by twinky (Member # 693) on :

quote:
Originally posted by MrSquicky:
Yeah, I get that that was your initial reason. What is your motive for this line of discussion?

I don't have [a didactic motivation]. I'm addressing comments and questions that are directed at me.

quote:
Originally posted by MrSquicky:
I'm not sure what comment of Tom's you are talking about. Is it the one at the top of this page?

Yes.

Posted by Samprimary (Member # 8561) on :

quote:
Originally posted by MrSquicky:
Samp, who seems to aspire to almost always being a jerk, but is giving Blayne problems for his posting history, not about this particular problem,

I guess if you think that my aspirations are 'be a jerk on hatrack' y'all prolly not had too many real jerks on hatrack.

Posted by rivka (Member # 4859) on :

quote:
Originally posted by King of Men:

quote:
That I don't recall a formula is hardly an indictment of the classes.
True, but people were dinging me for personal attacks.

So you decided to disguise the next one as an attack on twinky's teacher instead of on him?

Posted by The Genuine (Member # 11446) on :

Blayne, an easy way to do it with your typical D&D dice is this: add the lowest number (1) to the highest number (4, 6, 8, 10, 12, 20) and divide by two.

So you get 2½, 3½, 4½, 5½, 6½, and 10½.

Posted by Blayne Bradley (Member # 8565) on :

the reiman sums is sorta in the integration/anti derivitive portion which my calculus class didn't need to do.

Posted by King of Men (Member # 6684) on :

But which you, personally, apparently did need. Your faith in the overlap between what your classes teach you and what you need to know would be touching if it weren't so obviously a defense mechanism to cover laziness. And, by the way, these are not Riemann sums.

[ June 07, 2009, 09:49 PM: Message edited by: King of Men ]

Posted by The Genuine (Member # 11446) on :

Who is this King of Men fellow? Why is he such a ?

Posted by Sean Monahan (Member # 9334) on :

*I* didn't vote for him.

Posted by Samprimary (Member # 8561) on :

quote:
Originally posted by The Genuine:
Who is this King of Men fellow? Why is he such a ?

He holds this forum's office of Captain Atheism.

Everyone's gotta have one, it has many sacred duties.