#general discussion
1 messages · Page 2 of 1
A relation is a set of ordered pairs
So for example
a is an element from {0,1}
b=a²
So b is an element of {0,1} as well
The relation b=a² is written formally as {(0,0),(1,1)}
If a is in {0,1,2}
Then b is in {0,1,4}
Their relation is {(0,0),(1,1),(2,4)}
And {(1,2),(2,3),(3,4)}
but what is the notationif y is all the numbers in R?
hey
to the last parliament, nice job in turning this into a forum channel
lets see if texit works
$1+2=3$
Hebrews 12:1-2
nice
so its like for every y, the set contains (y, y+1)
is that good?
what does the comma mean in this context?
so basically this means like if our x value is a, then the y value is a + 1
im changing y to a here so as not to confuse it with the y axis
the notation (a, b) is called an ordered pair
like coordinate pairs
yes!
exactly
except we are dealing with parametric form or parametrization here, where a is a parameter
hey hebrew, do you know anything about deriving the integers from the natural numbers?
I heard it uses something call equivalent relations or smth
The set of all (y,y+1) where y is an element of R
Hey @dire sable
Found a way to say a number is smaller than another
if we can represent numbers as some sort of a set
It uses the proper subset relation btw
Hmm, interesting
Oh yeah, @long socket , there was an interesting video I've been wanting to share with you
A combinatorial proof that e ≤ 3.
Submitted for Summer of Math Exposition 2.
Collaboration with Enumerable: https://www.youtube.com/channel/UCBouaWpdXNk6Oo33rF9b7Ew
Special thanks to: https://mobile.twitter.com/dontthinkmeat
More on the binomial theorem: https://en.wikipedia.org/wiki/Binomial_theorem
#combinatorics #math
Chapters:
0:00 - I...
then it makes induction proofs possible
and makes inequalities a reality
just need to find a way to represent numbers as sets
btw, we are focused on doing things on the natural numbers
how do we adjust our stuff to integers?
hm
let n - n = 0
(assuming we defined subtraction)
we can prove that but that's for later
If we define multiplication we could go with n-2n, otherwise just 0-n
yeah
0 - n = -(n) = -n
let -n be the number that -n + n = 0
now how do we define operations with negative numbers?
Yeah, and those numbers can be added to the set of natural numbers
I think operations with negative numbers can use the definition 0-n for simplicity
let's do addition first
what is 3 + (-2)?
A lemma we can use is n + (-m) = n - m
so 3 + (-2) = 3 - 2
which is 1
what about (-3) + (-2)?
another thing we can use is (-n) + (-m) = -(n + m)
so that turns into -(3 + 2)
which is -5
We could also change it too 0-3-2, and use subtraction
We could assume multiplication and division are defined for natural numbers and try to apply it to negative numbers
multiplication is buffed addition, but what about division?
really?
Like if we have x/y=n, then that'd be x=yn solving for n
Yeah
Would defining division as the reciprocal of multiplication work?
Yeah, it should be
then we're stuck then
unless
we use subtraction
division is informally defined as a / b = c, where c is the the number of times a has to be subtracted by b in order for a to reach 0
I said informally because how do we "keep tract" of operations?
You could use multiplication too, so c is the value b has to be multiplied by to reach a
Also informally
in both definitions, we need a way to "keep tract" of operations
What math trick can we use?
Maybe we could just leave it as a=bc, and leave c as a variable while providing hardcoded values for a and b
That probably wouldn't work though
Yeah, that's probably a good idea
Yeah, I'm looking forward to how this question will be answered
Sup @dire sable
is it me or do I feel like we need to memorise every single identity when we reach calc?
also this -> https://www.youtube.com/watch?v=j5s0h42GfvM
There is actually a formula for the nth prime number! One was cleverly engineered in 1964 by C. P. Willans. But is it useful?
References:
Herbert Wilf, What is an answer?, The American Mathematical Monthly 89 (1982) 289-292.
https://doi.org/10.1080/00029890.1982.11995435
C. P. Willans, On formulae for the nth prime number, T...
Calc isn’t too bad with identities, the trig identities are a bit more difficult to memorize
At least that’s how it was for me
Oh yeah, I saw this a while ago
Although the formula isn’t useful at all, I love how it basically demonstrates a way to program with purely math
Wish it can be made faster
Yeah, that’s what Riemann’s hypothesis is for
oh hello there
Heyy
I wonder if anything new happened at math
I can’t think of anything big
Oh, I won’t be able to respond for a bit, I’ll try to as soon as I can
okay then
why is it that you can simplify rational expressions when you multiply then by the lcd?
Wdym?
like the equation t/25 - t/30 = 1
you multiply both sides by 60
and it will simplify to t = 60
I wonder why
the fractions cancel out..
isnt the lcd 150?
how?
ah
then in that case lcd is 60 ur right
and yes t = 60
For this, you would get $\frac{4t}{60}-\frac{3t}{60}=1\Rightarrow\frac{t}{60}=1\Rightarrow t=60$
Orthodox
The first part of that is gotten because you're multiplying by 1
$\frac{4}{4}\frac{t}{15} and \frac{3}{3}\frac{t}{20}$
Orthodox
<@&727457814523674674> what are some useful equations manipulation?
It seems that I need to master moving stuff around in a equation
X + X/1 = 3/2 for one
The server said that you can shift the denominator of a rational expression
1 + x/x = 3/2
Turns to 1 + x = 3x/2 for some reason
ah
thats weird
But does it still hold equality?
of course not.
oh wait nvm
to be safe, just do what you know
if ur not sure, dont perform the transposition
One, I did the thing
Second, not sure how would I solve for x without using quadratic techniques, which is something I didn't learn yet
u dont need quadratic techniques
wait for 1 + x/x = 3/2 is wrong already
x/x is 1
1 + 1 = 2
which is not 3/2
1+x / x
AH
Not that
Hebrews 12:1-2 | Vote for PRP
Hebrews 12:1-2 | Vote for PRP
ok great
now u have x on one side and 3/2 x on another
so this time we subtract x from both sides...
$1=\frac12x$
Hebrews 12:1-2 | Vote for PRP
this can also be written as $1=\frac x2$
Hebrews 12:1-2 | Vote for PRP
therefore the answer is?
The subtract x part
just do the same operation on both sides
Lemme try
ok
so yeah the only thing u need to remember is that in any equation, u can add, subtract, multiply, divide, etc. the same thing on both sides
How do I deal with the mixed rational expression?
For what reason?
it makes it easier
like
u can solve normal linear equations
And if I subtracted normally, I get 1 = (x)(3-2x/2x)
but u need to realize that rational equations can be reduced to linears
wait
can you show your steps?
one by one
ok u did this part correct
but pls write it as 3/2 x not x 3/2 so we can follow notation properly
ok so u subtracted x right
u have 3/2 of x and 1 of x being taken away from it on the right side
3/2 - 1 is?
1/2
ok
Can you rephrase this?
so u have 1 = 1/2 x
ok lets make this concrete
i have 1 and 1/2 apples
i take 1 away from it
i then have only half an apple left
right?
Yeah
You might want to latex this
Something I running into is when I try to break down the equation, I just get another rational expression, not a nice and simple whole one
Like before
@ebon depot
Hebrews 12:1-2 | Vote for PRP
Hebrews 12:1-2 | Vote for PRP
Hebrews 12:1-2 | Vote for PRP
Hebrews 12:1-2 | Vote for PRP
Hebrews 12:1-2 | Vote for PRP
Hold on
I can see how it works
In elementary math, they taught about how improper fractions can be converted to a mixed fraction
Guess that kinda applied to rational expressions, fractions with letters
Since p and q are numbers, you can use that fact pretty easily
@ebon depot guess I learned something
yes
3/2 = 1 1/2
nice!
How else can I convert rational equations to linear equations?
just multiplying by the denominator
ig thats all u can do
What you guys did from here is right
But this doesn't work
@long socket @ebon depot
$x+\frac{1}{x}=\frac{3}{2}$
Orthodox
Orthodox
For the left distribute
$xx+x\frac{1}{x}\Rightarrow x^2+\frac{x}{x}\Rightarrow x^2+1$
Orthodox
So we have $x^2+1=\frac{3x}{2}$
Orthodox
Orthodox
Hmm, there are no real solutions
Interesting, I might've just misread it
But
$x+\frac{1}{x}=\frac{3}{2}$ has no real solutions
Orthodox
@long socket @ebon depot Sorry for pinging you twice, but the first one was the beginning of it, here's the end
bruh this one is obvious, since you can just do x+1 = 3, x=2 and get x=2
oh yeah i forgot to point that out
ok
he never wanted quadratic techniques tho 💀
Yeah, that’s true, although it wouldn’t really have been possible without it
You did a good job explaining the rest of the problem though, I feel like I learned more about fractions as well❤️
👍🙂
It’s been slow unfortunately, I got caught up in other schoolwork. Still been able to have fun in math class though, we’re going over integrals now.
How’ve things been going for you?
Almost done with linear equations in two variables
Sweet, Claculus
I think I wanna write some informal things about natural numbers
Oh, that could be fun
Then use that to make a game of some sort
A math game no less
Albeit it's going to be hard explaining proofs and set theory
Yeah, but it’s probably going to be a fun challenge
Like before, what do you think with be the final boss of that game?
If it’s a person, probably Godel, but if it’s an equation or concept, maybe like power sets
Or introduce some calc just for fun
Not him again
Calc without negative numbers?
Maybe the game could introduce negative numbers
Still am figuring out the formal definition of negative numbers
Although it maybe like for the set of negative numbers and positive numbers, the exists one number from each set that add to 0
Okay
And what happens when I use numbers that aren't opposites of each other?
Like 1 + -2?
It only needs to exist, it’s not for all pairs
I meant what happens when I pick two numbers from each set and add them with the fact that they aren't opposites
And how do we even know that a number is the opposite of another number?
The definition makes it so the within the negative numbers set there will always exist the opposite number. It’s kinda like the definition will run through all the possibilities to see if the definition holds
And by doing that it provides the negative numbers
But wait
We didn't define the operations to work with negative numbers yet
I can define the operations with natural numbers using my homemade Presessor Theorm
I think the way the operation would work could be defined within the definition, as they are opposites
In my time dealing with the Z set, I use symbol - to kinda make the Z set possible
Btw, does it make sense to you?
That using a symbol in justifying ways is axiomatic?
Hm?
The Z set has been defined, so using it for further definitions works well
Can you define it now?
I’m not sure how to define it
I guess the set of all N numbers plus zero plus all N numbers with a minus sign in front
Notice the symbol being used
Also, I want to show you something
Oh, okay
Pretty neat hashing function
Right?
With a bit more set theory, we can make whatever hashing function we want
@dire sable
Just in case
Oh, sorry, I was just looking at it
What do you think?
Yeah, it seems like it’d work very well
Yeah, in both good and bad ways
The last time I've made some cool math stuff was the presessor therom
Last time for me was pointlessly looking at collatz conjecture
Don't worry buddy. Someday, you might make a dent in math even if it's just a little bit
Math is built about very tiny bits of stuff that is useful
Yeah, that’s true
My goal in math is of course to build it up from scratch
Using nothing but ZFC and logic
More or less
Oh, that reminds me
Hm?
https://i.redd.it/4o4y99b2v6x91.png
Pythagorean theorem in purely logical form
It's on quora, so I'm not sure if it's real, but it seems to give a pretty in depth explanation
Ah, yeah see ya, it was nice talking
@dire sable you there?
Ohh
I won't be able to talk long, sorry
But for natural numbers, would it be possible to define them by a unit?
I mean like kinda just declare that 1 exists, and build from there
I'm not sure if that's okay to do though
The axioms of natural numbers already did that
Zero exist and every number number that isn't zero has a successor
Hmm, that makes sense
@dire sable
In the name of godel
This works somehow
My definition of negative numbers
Oh hmm, it seems like some of this could also be used to define inequality operators
Defining -a + -b is tricky tho
Also what do you mean by that
Like if a-b is outside of the set of natural numbers, it indicates that a<b
I guess so
Distributive Property in clutch
Believe that the minus sign is a number(it is just -1) and you get that
Yeah, that tends to work pretty well
Suck on that equivalence relations
I can just algebra just fine
For rational I may need a bit more help
Yay for more operations
And without much set theory too
@dire sable
Sup there
I'm dealing with linear inequalities and happen to run into fractions that I can't get rid of
The math problem is 2x + 5y < 7
Y = (-2x/5) + (7/5)
I graphed the thing and it seems to need transformation if I want to use b with 5y
What do you mean?
Wait
,w graph 2x+5y>7
Sending query to Wolfram Alpha, please wait. 
An unexpected error occurred while processing your command!
The error has been reported and should be fixed soon.
If the error persists, please contact our friendly support team at our support guild!
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Hmm
Well, @long socket you would graph y<-2x/5+7/5, such that it would be shaded under the line
The shaded area represents the solutions
I meant finding the b of that equation
It's in slope-intercept form
And the b part is a fraction
Makes it a pain to graph
Oh, yeah, that’s true
But there’s no way to get rid of the fraction unfortunately
Oh, I need to head to school now, sorry
See you soon then
It's bullshit
I've read the article
There's a reason why it's BS
The Godel encoding really just uses a notation to express the direct equivalent of the expression
Godel forms are not even necessary
One can simply use 2nd-order logic notation
Honestly, I don’t really understand this, but thanks for letting me know! It’ll be interesting to look back on this if I gain more experience in the matter
Ah. Basically, there's primarily 1st and 2nd-order logic notation. 2nd-order is much more complex, but it lets you do more things.
Whoops, sorry I didn't see your reply. That seems interesting, thanks for the description
Can you give a example to me and my fellow colleague?
How would one define a relation? @dire sable
Likewise, what is the formal definition of a property?
Hmm, maybe for a relation, a comparison between properties of different parts of a set
While a property would be unique and/or non-unique characteristics of something that come together to form something that is unique
@long socket
Hm
It's a bit tricky to formally define
Say I have a relation y = x +1
So y is a member of the set Y
And x is a member of the set X
X is just N
Y is all of N's members plus 1
So 0 is in X but not Y
What can you see here?
Could the properties of a set be defined in relation to other sets that are already rigorously defined?
What do you mean by that?
In the example you gave, it's defining Y based off of N
Any two sets can work when defining a relation
As long as there is a way for members of one set relate to members of another set
Ohh, so general relations between sets
Yep
Hmm, could it be defined by iterating through elements of a set?
That works
Good morning!
Hello OP
Lol
Just discussing about relations
Go on
Oh, hey Yoav
You'd go on, I think, as you were talking
Anyways
If I gave you two sets
A is 1, -1, 2, -2, 3, -3
And B is 1, 2, 3, 4, 5, 6
Can you find the relation?
Would you be able to say it's a union between the absolute value of A, and the absolute value of 2A?
Challenge, no set operations
Oh, hmm
Yoav, can you define relations and properties for us?
A relation is a set of ordered pairs with the first element of each pair being from some set, and the other element from another set
Properties not so much
Unless you mean symmetry or transitivity and so on
So a relation is just a set then?
Given x, how would you find y in that relation set?
I haven't been able to figure this out, I was thinking A+3, but then there's be a 0 instead of 3
Yoav, correct me if I'm wrong, but I think that could be arbitrary
What are x and y?
A element in the set X and Y respectively
ah
well, you can't find y because this isn't necesserily a function
not any particular one
you can know it is from the set
$\qty{(x,y)\middle|y\in Y}$
yoavmal
Im learning calculus at age 13
Thats nice. I started at 15.
cool! make sure you focus on the intuition and not drown in the definitions
ok I will
Thats cool also thanks
Is there a formal definition/name of this animation on desmos: https://www.desmos.com/calculator/pteljfcfig
I thought that it kind of looked similar to a double pendulum
I made the graph cause I was bored
hello people, what is the formal definition of the "element of " relation?
No idea, but i'd imagine it's belonging or something like that
I'd say this looks very similar to Fourier sums
O ok thx I’ll take a look at that. But I’ve never rly heard of Fourier sums. Is it an advanced concept?
Depends on how you approach it
Effectively, it's about summing sine waves to get different functions
does the determinant of conics have any geometric significance?
i feel like it does but
i cant figure out how
is this necro?
i mean there had been no activities here since last year
Sorta? We had different channels before, they're just archived now
Wait
I fell for it
💀
Can anyone help me learn calc 2 its so hard
intuitively or formally?
is pair of straight lines a smooth curve?
depends on how do you treat it
elaborate
the issue here is
yeah its derivative is defined everywhere
so yeah its derivative is not defined on the point of intersection
again, it's complicated
if you treat it as a set of two lines
so you have
{line A, line B}
then you can easily make a function that does that
whereas saying a union of the set of all points in both lines
then, it is not smooth
depends, it can be
when can it be?
when all points in the two lines also satisfy an equation of the form $a(x-b)^2-c(y-d)^2=1$
yoavmal
why?
do they have to satisfy this equation too?
because that's how conic sections work
very helpful bro
so other conics also satisfy this equation?
sometimes
well, not others
but conic sections are parts of a 3d form
what
so like ellipse circle parabola
?
yes
but what is that equation?
$x^2-y^2=z^2$, with linear transformations accordingly
yoavmal
what
you are expecting too much from me
google "conic sections"
sorry, google "en passant"
Is it possible to calculate the values of trig functions using only algebra and geometry and not calculus
lmao
for some
yeah
but it's usually very tedious, and won't work for the majority of values
mainly because we do use calculus... to define trig functions
even in the geometric form, we need to define the length of a circle arc, and this is done using calculus
What kind of maths ultimately ended up interesting you?@open whale
Googology, which is really big yet finite numbers
One way to make a really big number is using the tree game
The longest game for a given number, we'll use n, of unique colours, is denoted TREE(n)
TREE(1)=1, TREE(2)=3
And TREE(3) is so big you cannot express it in physical terms conventionally
TREE(4) is even incredibly unimaginably larger
One number even larger than that is your mom's weight
Just kidding I like fractal geometry
Heh cool
Hey @topaz cobalt
Here it is!
Yep, I'm reading it too
i'll skim through it, i have homework to do
Nope, besides it will take me some time to figure out since I am sick lol
Ok tell me the remarks when you get the concept!
Will do
Actually the main purpose is partitions
wait
so, like, a number notation designed for one specific use?
Yeah but it also has additions , multiplication ect
So We can also see it as aa new way to write numbers in the case of big partitions
"...powerful enough to revolutionize the mathematics." is kind of a clickbait then
it doesnt "revolutionize the mathematics", it kinda just solves one little problem
I accept
Never be afraid of overselling yourself
Actually It was meant to write"It will revolutionize the mathematical world of Partitions"
font size 100 pt
Damn
so it says that uh
"This formula is best in the case of huge numbers such as 737747, ..."
Tell fast
you scale this method to numbers like 737747?
Use manual method!
which is?
Written in pdff
oh
oh i found it
isnt manual method the same as N.C. method but like only a one specific row
that yields only partitions of a specific scale
am i missing something?
Actually yes
You are missing some notations not mentioned in this pdf
Because these are just basics
Those notations minimise the time to a great extent!
Please can you tell me if it is helpful or not!
Yeah because the chart method can be used in smaller numbers but it will be useless in huge numbers!
so you have no method of getting an amount of partitions for large numbers?
We have it!
But that isn't in pdf
Because this pdf is just about basics
And the methods in this pdf will also work for huge numbers but if we want to find ""all partitions"" then it would be just some time taking!
Using advanced NumenCastical Functions will minimise the time by 95%
Here I meant that we should use manual method in huge numbers because drawing N.C chart in case of large numbers will be time taking NOT WRONG!
well then whats the point of the thing if it doesnt offer a faster or more convenient way of getting the results
Yes it minimises the time by 95%
I said above!
I just want you to rate my work please
@normal arrow
I don't think "minimising the time by 95%" is a small deal!
The best things I liked in NumenCasus are:--
Even a 2nd grade student can easily understand NumenCasus basics!
And also it is always accurate
im thinkin
that maybe you should look into the uh
generating functions
if you're lucky enough, you can find a closed form solution for amount of partitions of any number
I know a formula for number of partitions already
n² maybe!
Because it is still in research
But the main thing I am asking to you is to rate my concept a little so that I can get that I am doing right or not!
eh
you're trying to make a system being able to be used by even 2nd grade pupils but really
its only goal is solving a single problem
Ok
its only worth developing a system if it allows solving a whole group of problems
like p-adics
or it makes computation easier/faster
for things like these, you should pretty much just say
"here's a closed form solution and few fun facts"
Should I continue researching on it to find its other functions or It is worthless!
First of all the main thing you aren't understanding about NumenCasus is "Using it as a new system can be a choice, but it isn't a new system!" It can also be used like a Identity, theorem or formula.
I already said that "It may be a new system for writing positive integers but it is used in partition numbers only" and I don't think we can say it a whole new system then!
Just take it as a linear function!
try to find a closed form solution and prove it
Ok
Can somebody tell me what I should do? I had a 2 tutors in elementary, and 2 now. I am in 7th grade and have a good teacher who everyone understand but me. I had an 89 until today I got two 50’s and now have a 0. I think I might have dyscalculia. I don’t really study besides from when I was in elementary and now my 2 tutoring sessions, and I’ve never been that good. I just need help on what to do, I don’t want to fail. Any advice?
Study without outside stimulus
Maths is hard to learn, but it's doable
Also you can see a doctor to get diagnosed
But the first step is to study by yourself
Anything that stops you from is the issue
hey!
anyone good at math here? i am working on finding a formula for prime numbers and i would love to work with someone !
there is one already
so you're kind of too late
unless you want to make a better one
which will require, like, a very deep understanding of mathematics
its basically related to an unsolved problem
how would you define a formula?
it's important to know what exactly are you trying to achieve
Hey
Zeta functions right? That’s kind of what I’m talking about solving
Plug in “n” get the nth prime
essentially a function
well, i have the "formula" for you
it's a function so that
f(n) = nth prime
i think what you're really asking is
if there's a way to calculate it
yea
@open whale yes, since there is no known approach i am looking at areas of math that i think will help narrow down a solution
@open whalenumber theory obviously, statistics, and calculus for things like zeta functions
As far as I recall there is no formula
there is one
Formulas for the nth prime number actually exist! One was cleverly engineered in 1964 by C. P. Willans. But is it useful?
References:
Herbert Wilf, What is an answer?, The American Mathematical Monthly 89 (1982) 289-292.
https://doi.org/10.1080/00029890.1982.11995435
C. P. Willans, On formulae for the nth prime number, The M...
whats the best way to learn quadratic inequalities
starting from absolute value inequalities
@normal arrowthat uses a floor function tho....not quite something im looking to find
trust me, if it can generate primes, then having a floor function is not a big deal
a bigger deal is making it easy to compute
and not some scary nested sum
hi
im new here because I had a stupid thought that I know im not smart enough to figure out lol
so basically I made a 3d scatterplot of all rgb values (255x255x255) and the thing is very trippy.
it has some very strange properties depending on the perspective you look at it from, which got me wondering about a 2d grid question I saw before.
if you have grid of squares like a chess board, the whole thing is a big square but how many squares are contained within (regardless of size)? so in the chess board example a single space would be a square but 4 spaces 2x2 would also count for the question because it is also a square and the 4 squares inside of it would count separately as well.
if you see where i'm going with this the next question is obviously: how many cubes are in that 255x255x255 cube I made?
here's the cube and a small glimpse of the trippiness inside for reference, if it helps XD
gay cube
can we come up with some fancy function that can solve intersections between quadratic and exponential like Lambert-W solves linear = exponential
generalize it to taylor, really
How does one phrase and prove Taylor's theorem, over the complex numbers?
Hmm
I'd suppose i'd want to clarify Taylor's theorem first
Sorry, differentiability
$f'(z)=\lim_{h(\in\mathbb Z)\to0}\frac{f(z+h)-f(z)}{h}$
yoavmal
yoavmal
Now, how do I convert this to real and complex methods
$f'(z)=\lim_{a+bi\to0}\frac{f(z+a+bi)-f(z)}{a+bi}$
yoavmal
$f'(z)=\lim_{a+bi\to0}\frac{(f(z+a+bi)-f(z))(a-bi)}{a^2+b^2}$
yoavmal
$f'(z)=\lim_{a+bi\to0}\frac{a(f(z+a+bi)-f(z))-b(f(z+a+bi)-f(z))i}{a^2+b^2}$
yoavmal
Now I suppose we can decompose f to g+hi
Hmm, what if I do it earlier
$f'(z)=g'(z)+h'(z)i$
yoavmal
$f'(z)=\lim_{d\to0}\frac{g(z+d)-g(z)}{d}+\lim_{d\to0}\frac{h(z+d)i-h(z)i}{d}$
yoavmal
$f'(z)=\lim_{d\to0}\frac{g(z+d)-g(z)}{d}+i\lim_{d\to0}\frac{h(z+d)-h(z)}{d}$
yoavmal
So g,h must be differentiable
But, that isn't enough, no?
There has to be some connection between them
$f'(z)=\lim_{d\to0}\qty(\frac{g(z+d)-g(z)}{d}+\frac{h(z+d)-h(z)}{d}i)$
yoavmal
Well surely it's equivalent
Then it must be that if f is not differentiable, at least one of those isn't
Right, well, what if I express each as a function on two variables?
$f(a+bi)=g(a,b)+h(a,b)i$
yoavmal
Now I can take partial derivatives
So $\pdv{a}f(a+bi)=\pdv{a}g(a+bi)+i\pdv{a}h(a+bi)$
yoavmal
yoavmal
$\lim_{n\to\infty}\abs{f'(z)-f(z_n)}=0$
yoavmal
yoavmal
No, well,
I'll work with g only for now
$\lim_{n\to\infty}\frac{g(z+d_n)-g(z)}{d_n}$
yoavmal
yoavmal
$\lim_{n\to\infty}\frac{(g(a_n+b_ni)-g(0))(a_n-b_ni)}{a_n^2+b_n^2}$
yoavmal
So this goes to infinity unless the left side converges
To 0
$\lim_{n\to\infty}\frac{g(a_n+b_ni)-g(0)}{\sqrt{a_n^2+b_n^2}}$
yoavmal
Hmm
$f'(z)=\lim_{a+bi\to0}\frac{a(f(z+a+bi)-f(z))-b(f(z+a+bi)-f(z))i}{a^2+b^2}$
yoavmal
$f'(z)=\lim_{a+bi\to0}\frac{a(g(z+a+bi)-g(z)+h(z+a+bi)i-h(z)i)-b(g(z+a+bi)-g(z)+h(z+a+bi)i-h(z)i)i}{a^2+b^2}$
yoavmal
$f'(z)=\lim_{a+bi\to0}\frac{ag(z+a+bi)-ag(z)+ah(z+a+bi)i-ah(z)i-bg(z+a+bi)i+bg(z)i-bh(z+a+bi)i+bh(z)ii}{a^2+b^2}$
yoavmal
$f'(z)=\lim_{a+bi\to0}\frac{ag(z+a+bi)-ag(z)+ah(z+a+bi)i-ah(z)i-bg(z+a+bi)i+bg(z)i-bh(z+a+bi)ii+bh(z)ii}{a^2+b^2}$
yoavmal
$f'(z)=\lim_{a+bi\to0}\frac{ag(z+a+bi)-ag(z)+ah(z+a+bi)i-ah(z)i-bg(z+a+bi)i+bg(z)i+bh(z+a+bi)-bh(z)}{a^2+b^2}$
yoavmal
$f'(z)=\lim_{a+bi\to0}\frac{(ag(z+a+bi)-ag(z)+bh(z+a+bi)-bh(z))+(ah(z+a+bi)-ah(z)-bg(z+a+bi)+bg(z))i}{a^2+b^2}$
yoavmal
$f'(z)=\lim_{a+bi\to0}\frac{(ag(z+a+bi)-ag(z)+bh(z+a+bi)-bh(z))}{a^2+b^2}+i\lim_{a+bi\to0}\frac{(ah(z+a+bi)-ah(z)-bg(z+a+bi)+bg(z))}{a^2+b^2}$
yoavmal
ok i'm on computer
i may have done wrong calculations
$\lim_{n\to\infty}\frac{f(z+a_n+b_ni)-f(z)}{a_n+b_ni}$
yoavmal
$\lim_{n\to\infty}\frac{g(z+a_n+b_ni)-g(z)+h(z+a_n+b_ni)i-h(z)i}{a_n+b_ni}$
yoavmal
ok
i have a better idea
if $f$ is differentiable in some region $s=\qty{z\middle|\abs{z-z_0}\leq r}$ around $z_0$
yoavmal
and also $f(z_0)=f(z)$ for some $z\in s$
yoavmal
then there is some $c\in s$ such that $f'(c)=0$
yoavmal
is that correct?
that would require proof
how does the regular proof go? it uses weierstrass's extremum theorem
how do i convert that to complex numbers?
i need...
well, $\abs{f(z)}$ takes a minimum and maximum in the closed region
yoavmal
can i say that if $|f(z)|$ is an extremum point and differentiable, then $f'(z)=0$?
yoavmal
that requires fermat's theorem
how is fermat's theorem proven then?
,w fermat's theorem
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hmm
what if i try prove it myself
if it is an extremum point, lets assume without loss of generality that a maximum point
in the reals
$x_0$ is a maximum point if there is some environment $\abs{x-x_0}<\varepsilon$ such that $f(x)\leq f(x_0)$
yoavmal
how would that work in the complex numbers then?
wwell, no, i want to prove it first off
the derivative
so if there is some $\varepsilon$ that satisfies this, then $\lim_{h\to0}\frac{f(x_0+h)-f(x_0)}{h}=0$
assuming the function is differentiable, of course
yoavmal
well, by definition, $\lim_{h\to0}\frac{f(x_0+h)-f(x_0)}{h}=0$ means that for all $\varepsilon>0$ there is $\delta>0$ such that for all $\abs{x-x_0}<\delta$, $\abs{\frac{f(x)-f(x_0)}{x-x_0}}<\varepsilon$
so
yoavmal
yoavmal
now, lets say x>x0
then we get
well, first off
$\frac{f(x_0)-f(x)}{\abs{x-x_0}}<\varepsilon$
yoavmal
this is still true
$\frac{f(x_0)-f(x)}{\abs{x_0-x}}<\varepsilon$
and for convenience
yoavmal
how do i show that
uhhh
well, lets assume the derivative is not 0
then, without loss of generality, $\lim_{h\to0}\frac{f(x_0+h)-f(x_0)}{h}>0$
yoavmal
yoavmal
such that $f(x)>f(x_0)$
yoavmal
and this is a contradiction
is that valid?
no, well, it loses all meaning since extremum points are uhh
nonexistent for most functions in the complex plane
no?
no, actually
hmm
maybe i can find a point that does it without the extremum theorem?
hmm, well, first the environment
it has to be between z0 and z
so
$\abs{c-\frac{z_0+z}{2}}<\abs{z-z_0}$
yoavmal
$\abs{\frac{c-z_0+c-z}{2}}<\abs{z_0-z}$
yoavmal
$\abs{\frac{c-z_0}{2}+\frac{c-z}{2}}<\abs{z_0-z}$
yoavmal
alright, lets say i understand something here
lets take sine
cosine is better since it's at 0
$\cos'(0)=0$
yoavmal
how do i show that it's true in the complex plane
well, the analytic continuation of cosine
$\cos(z)=\sum_{n=0}^\infty\frac{(-1)^nz^{2n}}{(2n)!}$
yoavmal
so all i need to do is prove differentiation of polynomials
is valid there
but no, i want to do it without knowing the formula
lets say for a polynomial, how would i prove it
what if i simply state
there is some environment $\abs{z-z_0}<\varepsilon$
yoavmal
so that for all z in this environment
$\operatorname{re}(f(z))<\operatorname{re}(f(z_0))$
yoavmal
yoavmal
right, i can work with this
is this correct though?
lets take it with cosine
,calc cos(0)
Result:
1
,calc cos(0.01i)
Result:
1.0000500004167
aha, it's not
right, because cosh is not
it's a minimum point
huh
maybe it can be a minimum point on one and a maximum point on the other?
does that count possibly?
so then i can say
$\abs{f(z_0)}>\abs{f(z_0+\varepsilon)}$ and also $\abs{f(z_0)}<\abs{f(z_0+\varepsilon i)}$
yoavmal
yoavmal
obviously no
since this is only two axis, it could go wacky all over the rest
however, it must be differentiable
so maybe not too wacky
what if i try to apply polynomial stuff here again
like, i know 0 is a minimum point of x^2
so what properties does z^2 have at 0
$\dv{z^2}{z}=2z$
yoavmal
so the derivative in this case is a scalar of the actual point
it is always pointing away from the point itself
what if i take a more complex function
where this sin't true
such as
$z^2+z^4$?
yoavmal
yoavmal
yoavmal
yoavmal
$=0.2i-0.04$
yoavmal
this is clearly not pointing in the direction itself
but it is very close to doing so, actually
so i'd imagine the limit does that
yep
it's insignificant here, the main thing is the 2z still
and if i do -z, it pulls towards the point
and it'd be a maximum point itsead
ok, i can work with this
so
i want to find a point who's derivative is always pointing away in all directions
how do i say that without differentiating proper
$f(x)\cdot x<f(x_0)\cdot x_0$ i suppose?
yoavmal
there is some environment that satisfies this
no, that isn't right
it should be
$f(x)(x-x_0)<f(x_0)(x-x_0)$
yoavmal
this creates a difference between left and right
this isn't right, but it's closer
and it would create the appropriate angle in complex numbers
so now the absolute value matters
i want |f(x)|<|f(x0)|
but only in the reals
uhhh
hmm, derivative is
well
$\dv{f(z)}{z}-kz\to0$
yoavmal