At what point do you start forgetting how to do math...?

[chesebert]

I haven't touched any real math in like 10 years and I think I regressed all the way back to middle school algebra. Dang it!

I have recently gotten interested in machine learning and deep learning and have been looking at online classes. The list of prereqs are making my head hurt: diffeq, linear algebra, matlab skill, data structures, probability theories, big O notation.

I spent a shit load of time/money in college learning how to do these things and now I remember nothing. I think it will be a while before I can get up to speed...

Has anyone here ever tried to pick up an abandoned skill? How do you keep yourself motivated?

[ender]

The real question is whether you ever knew it or just coasted through college.

I find if I revisit something I actually learned, I pick it up quickly. But if it's something I learned well enough to get by but not actually learned, then... :'(

[Jack]

 

I have recently gotten interested in machine learning and deep learning and have been looking at online classes. The list of prereqs are making my head hurt: diffeq, linear algebra, matlab skill, data structures, probability theories, big O notation.

Don't worry, once you get into the class it'll refresh your memory. As long as you can answer questions like "what's the difference between an array and a linked list?" and "which is better, O(n log(n)) or O(n²)?" you'll be fine.

[Rural]

I'm actually (re?)taking a math class (that I exempted originally) at the college where I am a professor now. What I'm finding is that the concepts of the class come back pretty quickly. What's taking a little longer is speed and precision. I'm slow and I make careless arithmetic mistakes. That's improving, but slowly, a month into the semester.


For me, it's been a little over thirty years since I've thought systematically about this particular branch of math if that gives you any kind of gauge, though I have used it here and there over the years, some parts more than others (and a few not at all - not surprisingly, they're coming back the slowest).

[Financial.Velociraptor]

I start forgetting how to do math around the 5th drink...

[jrhampt]

I did a master's in math with a concentration in statistics over 10 years after finishing undergrad.  It was painful and slow; I was extremely rusty, and it was frustrating because I knew it used to be easy for me.

[GuitarStv]

I didn't really learn any particular subject in university.  My engineering degree just taught me how to learn, and how to learn quickly.

I've forgotten nearly everything that I once knew.  Much of it was theoretical, and never made sense to me.  Any time a need for something comes up at work or in the real world though I hit the internet and the library, refresh my knowledge and am able to hit the ground running.  Using a concrete example I'm always able to make sense of and figure out how to approach a problem.

[matchewed]

Switching from a career that dealt a small amount in statistics to working on getting a degree in and actually in Manufacturing Engineering, I can see that I use math on the school end a great deal and not so much in my work. Reference books, machinist guides and the like are my work bread and butter. Applying calculus is the same in school. I'm sure in 10 years I'll have forgotten most of the calculus again.

There certainly was some rust to knock off when I went back to school. Took a bit but it wasn't forgotten, just buried under mounds of life.

[marty998]

9 years out I have forgotten differential equations and matrix arithmetic (though could probably pick that one up again after an hour or 2 intense refreshing from my brother). n-space maths orthogonals and orthonormals were always a bit weird to me - as soon as you start trying to visualise more than 3 dimensions your brain explodes so it's best to just do the sums and not think about it).

Still remember basic complex numbers, basic calculus, logs (useful for figuring out compound interest calcs :D).

Might have some difficulty with calculus applications and higher level trig nowadays. In no way is it necessary for me to know it for my day to day job though...

[dividendman]

I would say a month of two after learning it. I have a degree in math too, hahaha.

I recall these terms but don't know them without looking it up:

Fourier transforms... i'm pretty sure there are other transforms too, what are they transforming again? i dunno
All of the trigonomtery terms: sine/cosine/tangent etc. I know what the graphs look like but forget how they relate to circles and crap
Bernoulli trials... that's something i'm sure of it
Wasn't l'hopital's rule a thing?
Chinese remainder theorem.. i remember that because we had jokes about that in class. There were lots of theorems I can't recall now or wouldn't be able to derive easily
A bunch of crap in graph theory about coloring and covering and vertices... yeah... automorphism? yup, that's a thing too...

And a bunch of others. I couldn't tell you what any of them mean though without looking it up/reading up on it for a couple of hours.

[MayDay]

I didn't really learn any particular subject in university.  My engineering degree just taught me how to learn, and how to learn quickly.

I've forgotten nearly everything that I once knew.  Much of it was theoretical, and never made sense to me.  Any time a need for something comes up at work or in the real world though I hit the internet and the library, refresh my knowledge and am able to hit the ground running.  Using a concrete example I'm always able to make sense of and figure out how to approach a problem.

I feel like I've forgotten all my engineering and math and ALL TIMES A BILLION of my organic chemistry, even though I was a whiz in college. 

I pick it up quickly, but I have to go way back to the beginning, which means even at a quick pace it takes quite a while to get up to speed.

It isn't fun.

[marty998]

I would say a month of two after learning it. I have a degree in math too, hahaha.

I recall these terms but don't know them without looking it up:

Fourier transforms... i'm pretty sure there are other transforms too, what are they transforming again? i dunno
All of the trigonomtery terms: sine/cosine/tangent etc. I know what the graphs look like but forget how they relate to circles and crap
Bernoulli trials... that's something i'm sure of it
Wasn't l'hopital's rule a thing?
Chinese remainder theorem.. i remember that because we had jokes about that in class. There were lots of theorems I can't recall now or wouldn't be able to derive easily
A bunch of crap in graph theory about coloring and covering and vertices... yeah... automorphism? yup, that's a thing too...

And a bunch of others. I couldn't tell you what any of them mean though without looking it up/reading up on it for a couple of hours.

oo oo oo! L'hopital! Something about limits? and 0/0 or infinity over infinity?

I remember something lol... wouldn't have a flying fucking idea how to go about using the rule though hehehe.

We used to joke about real and unreal roots (of polynomials). Not the most mature bunch of berries at age 17.

[Sibley]

I suspect the phrase "use it or lose it" applies. If you're actively using those skills, having to remember the details, etc, then your brain is going to retain it. If you're not, then your brain doesn't devote resources to it. Why waste limited resources on something that isn't being used?

[Lis]

I suspect the phrase "use it or lose it" applies. If you're actively using those skills, having to remember the details, etc, then your brain is going to retain it. If you're not, then your brain doesn't devote resources to it. Why waste limited resources on something that isn't being used?

Yup. Once upon a time I was really good at calculus. Trig and me were best buddies. Loved it all.

I do a weekly pub trivia with friends and they asked us a basic geometry question. None of us had any clue.

Nothing like pub trivia to make you feel real dumb, real quick.

[MrMoogle]

I suspect the phrase "use it or lose it" applies. If you're actively using those skills, having to remember the details, etc, then your brain is going to retain it. If you're not, then your brain doesn't devote resources to it. Why waste limited resources on something that isn't being used?

Yup. Once upon a time I was really good at calculus. Trig and me were best buddies. Loved it all.

I do a weekly pub trivia with friends and they asked us a basic geometry question. None of us had any clue.

Nothing like pub trivia to make you feel real dumb, real quick.

Definitely use it or lose it, although how long depends on the person.  I never liked math questions at trivia.  As an engineer, I use lots of math, none of it has been asked in trivia.  But I'm a lot slower with some things than I was in high school.  Now, I tend to pull out a calculator, instead of doing it in my head.  Oh things have changed.

[scottish]

If you want a low math intro to machine learning you might look at the 'Mahout in Action' book...    IIRC you don't have to learn much about stochastic gradient descent, collaborative filtering, singular value decomposition or any of the pesky stuff to understand Mahout.

[MoonLiteNite]

when i was like 14 it hit me how much my parents brained washed me. Been trying to forget it ever since and make room for usefull info, like spelling (that was a joke!)

[sisto]

I think it will all come back to you. Until recently I hadn't used UNIX/Linux. I've been in management for quite some time and recently started doing more technical work again. I had to figure out how to get back into my UNIX account and start using it again and it slowly all started coming back.

[dragoncar]

I really can't remember anything more than a couple years in the past.  Big stuff, sure.  But for everything else, I have to access the big memory bank in the sky.  Even on tests in college I would sometimes re-derive the equation from first principles when I couldn't remember it for a test

[GuitarStv]

I really can't remember anything more than a couple years in the past.  Big stuff, sure.  But for everything else, I have to access the big memory bank in the sky.  Even on tests in college I would sometimes re-derive the equation from first principles when I couldn't remember it for a test

My approach to most physics problems:

- figure out what the final units for the answer have to be
- check the data you're given
- start mixing equations together until you get those units from the units of the data you were given

it works like a charm.

[dividendman]

I really can't remember anything more than a couple years in the past.  Big stuff, sure.  But for everything else, I have to access the big memory bank in the sky.  Even on tests in college I would sometimes re-derive the equation from first principles when I couldn't remember it for a test

My approach to most physics problems:

- figure out what the final units for the answer have to be
- check the data you're given
- start mixing equations together until you get those units from the units of the data you were given

it works like a charm.

Yeah, that works well for some stuff. But some constants and crap have crazy "units" if I'm recalling correctly. Some new combo units are hard to remember too! Like a Newton being kg*m/s^2 is easy but some of the more complicated ones are hard to remember!

[Rural]

Well you guys, I'm getting steadily better and faster, and I made a 94 on the first test. So maybe there's hope, even after decades.

[Sylly]

I always joke that I have limited capacity for math -- as I learn advanced math, I forget the basics. Now that I'm forgetting all the advanced math I learned in college, I can do simple arithmetic again!

Also trying to get into machine learning, and fortunately did not forget all my linear algebra, though it's a far cry from what I could do 12 years ago.

[sisto]

Well you guys, I'm getting steadily better and faster, and I made a 94 on the first test. So maybe there's hope, even after decades.

Good job!