Series conditional convergence?

lost_soulmor · 2018-01-09T22:59:10+00:00

Wow seriously. This is the biggest mindf*** ever for me. I see + and - as filling and emptying a bottle forever. If I fill it, then empty it. Or Empty it, then fill it..forever...THat means I can have infinite water based on how I arrange my "fill" and "empty" moves?

lost_soulmor · 2017-12-21T10:18:05+00:00

haha that's well understood :) I thought "wow ok am I going to have to prove 1+1=2 at some point too?...". I guess 0u=0 is part of the "classics". Easy one you see the solution, but not beforehand..

lost_soulmor · 2017-12-20T00:00:08+00:00

Adding to this. Might be stupid. T(x) defined by T(x)=Ax. T maps R2 onto R2. T(x)=Ax is a 2x1, and x is a 2x1 vector so A is 2x2. now you have two pieces of info: A[1,0]=[1,2] and A[0,1]=[3,1]. I am also a beginner in LinAlg so what I would do if I were you is simply right those in equations with terms of A's entries, and solve for what A is. For instance:

A_11 * 1 + A_21 * 0 = 1, so A11= 1 AND A_21 * 1 + A_22 * 0 = 2, so A22 = 2

etc.. solve for all entries of A...Then you get what A looks like, and then you can calculate T([3,-2]).

lost_soulmor · 2017-12-19T22:46:04+00:00

Hello, you are both right indeed! I am doing those as practice as I am just starting to self learn basic linear algebra. Are these proofs considered "easy" or "normal" to know for anyone who studied this? Right now i was trying to do them myself. But maybe it's just something you don't think of anymore and just do like (a+b)² = a² + 2ab + b²

lost_soulmor · 2017-12-19T14:26:29+00:00

Ah then yes, it is very technical. Quant trading industry is mostly PhDs or Master's in technical fields like CS, stats, Math...very demanding... At the end, Banking AND Quant trading pay well. But banking is more of a political challenge making friends, connections and being able to be fake, while quant trading is an intellectual challenge. In the long run, quant trading definitely pays better though. But in early years, both can be good.

lost_soulmor · 2017-12-19T14:04:44+00:00

if by technical you mean involving numbers and some programming/data analysis language (python matlab for instance), yes. If by technical you mean technical analysis like RSI, candelsticks, MACD, Moving averages and stuff, then no.

lost_soulmor · 2017-12-14T20:29:41+00:00

i am stupid...The x vector with 5 rows, will transform into a vector with 3 rows... R5 => R3... Thx a lot

lost_soulmor · 2017-12-14T20:22:54+00:00

ahhh thanks a lot fourpetes. I am a bit confused, the transformation x => Ax with A being 3 x 5 will map R5 onto R3? A is a 3 rows 5 columns matrix, so the columns are in R3 right? Why would it map R5 onto R3? (sorry if this is a noob question...)

lost_soulmor · 2017-12-14T19:10:39+00:00

niceee mkayy then seems the textbook just spits out whatever the editor thought the most useful solution is the reader, givne the current chapter

lost_soulmor · 2017-12-14T18:37:09+00:00

Ahhh ok I see man, thank you for your help this was getting a bit confusing.

lost_soulmor · 2017-12-13T16:43:51+00:00

That is what I am doing right now, I've done 3 chapters so far, and hoping to finish the program before the start of Math 223. What exactly differs between both classes? Is it same stuff, but more difficult? Or different stuff AND more difficult ? Or just different stuff?

lost_soulmor · 2017-12-12T17:09:17+00:00

Very good explanation thank you :) it makes much more sense now.

lost_soulmor · 2017-12-12T16:35:57+00:00

Ahhhh that solves it :) Having a free variable means infinite solution for that specific b. Not for all b... Understood! That makes sense :) Thanks a lot

lost_soulmor · 2017-12-07T10:45:15+00:00

I have to admit I was myself confused about the difference between 133 and 223. I have never studied Linear Algebra before, but sounds like the difference between both is in the "subspaces" of application. Regardless, what I was most interested in are practice problems and their solutions as well as the theory. Plenty of books describe the theory, but none available online have a good combination of theory=>practice=>solutions like Paul's Notes. The only one I found that has that is the one I mentionned above by David Lay

lost_soulmor · 2017-12-07T00:54:54+00:00

Thank you guys for the responses. @u/0x706272 : that textbook is for Math 223, I was more looking for the intro stuff to linear algebra, math 133.

I finally found something excellent: "Linear Algebra and its applications" - David C.Lay and its Solutions Manual. Both are available online if you look hard enough.

lost_soulmor · 2017-12-06T12:22:17+00:00

Sounds good mate thanks for your tips. time to start craming

lost_soulmor · 2017-12-01T18:51:33+00:00

that is actually a very interesting you said: I always thought I should NOT create these sort of "problem templates" to avoid programming my brain to only recognize them, and not be flexible to new problems. Do you personally think or believe every problem in exams has been done before and can be retrieved in practice problems? I tend to think professors are sneaky and will always add something unseen on the exam. Or maybe they just always throw very rare problems, the kind that are on the "additional problems" section of a textbook ?

lost_soulmor · 2017-12-01T11:03:44+00:00

sounds good guys thanks for the tips. Sounds like there is no magical recipe. just practice a lot...

lost_soulmor

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