Mathematics

12:01 AM

Yes, you're almost half my age ...

hello

can someone quickly help me out - i forgot what it is called when you have two integrals or sums where the bounds of the inner one depend on the value of the outer one i.e. integrate over x from 0 to 1 and y from 0 to x

ah, convolution is the word i was looking for :)

MrWho

1:24 AM

@skullpatrol @DanielFischer : Is it bad to take Calc I and II + Linear algebra + physics in the freshman semester of physics?

Daniel Fischer

I don't know. Can you even take Calc I and Calc II in parallel?

MrWho

@DanielFischer I can, I think

@DanielFischer I know the bone structure of calc I and II

I'm just no skillful in linear algebra and multi variable calculus.

@DanielFischer Does it harm?

Daniel Fischer

I mean, "are they offered in the same semester?" I'd have thought they were offered in alternating semesters.

skullpatrol

I would not recommend it.

MrWho

@skullpatrol @DanielFischer They're offered in different semester, since I was late, most of the classes are closed, right now, I'm thinking of rescheduling the whole program.

I have to register right now !

I do really need your advices.

skullpatrol

1:33 AM

Remember math builds on itself.

Daniel Fischer

I can't advise on that @MrWho. Only generally, don't bite off more than you can chew, but enough that you have something to chew on.

MrWho

@DanielFischer I know what you're saying,tell me your opinion about this : Calc I + Linear Algebra + Fundamentals of Chemistry + Lab + Social and behavioral sciences?

Daniel Fischer

Sorry, no idea.

MrWho

@DanielFischer The question is, does linear algebra rely on calc I and II?

Do I have to know the whole calc to take linear algebra in Uni?

Daniel Fischer

@MrWho Linear algebra doesn't need Calc or anything. You need linear algebra for almost everything, however, so it's a good idea to learn that early.

MrWho

1:40 AM

@DanielFischer So if I put linear algebra in First semester it's good?

Daniel Fischer

And good night, everybody, I'm off to bed.

@MrWho Yes, that's fine.

MrWho

@DanielFischer Oh thanks, bye :)

Mike Miller

bonjourno

Mike Miller

2:07 AM

goodbyeo

900 sit-ups a day

3:51 AM

I wonder if this is the record for length of suspension on SE. Anyone seen longer?

Mike Miller

4:06 AM

@900sit-upsaday I've seen five-year ones, but not 10

Pedro Tamaroff

4:37 AM

@900sit-upsaday WAT.

That's amazing.

The Substitute

4:49 AM

Off topic: When defining the rationals by the cartesian product of the integers and the natural numbers modded out by ~ where $(a,b) ~ (c,d)$ if $ad=bc,$ how does one show transitivity without using division?

If $(a,b)~(c,d)~(e,f)$, then $ad=bc$ and $cf=ed$. I'd like to say $(a,b)~(e,f)$ since $e/f = c/d = a/b$, however, I don't feel like I should allow to divide since that would be using the fact that we already have rationals (while I'm in the process of defining the rationals).

AndrewG

if $(a,b)$ ~ $(c,d)$ and $(c,d)$ ~ $(e,f)$ then $ad = bc$ and $cf = de$, so $daf = adf = bcf = bde = dbe$ (I think?) implies $af = be$

Jasper Loy

5:07 AM

@MrWho It would be good to take linear algebra before multivariable calculus.

The Substitute

@AndrewG, yes, that's it

AndrewG

you may need to mention that there exists a g such that $(d,1) = (1,g)$ for that last implication

but that sort of is "using division"

Martin Sleziak

5:27 AM

It's not using division. It is using cancellation law. (Which is valid in any integral domain.)

The Substitute

@MartinSleziak yes. thanks

Alec Teal

6:04 AM

Morning

Jasper Loy

7:45 AM

@DanielFischer I just found out that integrals of Banach-valued functions are called Bochner integrals, and that there are manifolds more general than Banach manifolds called Frechet manifolds.

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$Mathematics$ Mathematics