The other one is over the bump limit
Anyone knows the answers to these?
I know the answer would differ depending on the program, amount of students in said program, etc., but is it common to not be given any type of assistantship during the first year of a Master's degree?
>>8097066
I would guess A for both, but I really have no clue.
>>8097066
Use snell's Law. The index of refraction of vacuum is less than the index of refraction of air, so that means the angle in vacuum has to be larger than the the angle in air.
Now look at pic related. The red lines are the rays of light, and the blue lines represent the surface between air and vacuum and the lines normal to the surface. Snell's law applies to the angle between the light ray and line normal to the surface.
For question 7 (box labelled 8 in the picture) notice the angle the light makes with the normal line in air is smaller than it is in vacuum, just as we stated it should be from Snell's law. Now from an observer in space looking at the system (that's us looking at pic related) it appears that the light ray is pointed above the moon. So for number 7 the answer would be C. The same reasoning applies to question 8 (box 9), except it appears that the laser is pointed under the moon.
>>8097154
Could the light refract the opposite direction at the same angle, like pic?
For my complementary functions I get
x = A exp(it)
y = B exp(it)
And for the particular integrals I guess
x = at + b
y = ct + d
But this results in the general solution
x = A exp(it)
y = t + B exp(it)
Which makes the solutions obtained from the boundary conditions inconsistent with the original equations. I'll humour them a second:
t = 0, x = 0, y = 1
A = 0 -> x = 0
B = 1 -> y = t + exp (it)
Back in the first equation:
0 + 1 + i exp (it) + 0 = 1
Which means i exp (it) = 0...
I have no idea where I went wrong. Help! Exams are in two weeks...
If I blow on my hand with my mouth wide open it feels hot. But if I blow on my hand with my mouth barely open it feels cold. Why?
>>8097215
no it still feels hot. you're the one who blows more.
when you blow faster, the air current drags surrounding air with it. You also make the water particles on your hand evaporate much faster which cools it.
>>8097215
My assumption is that with the small amount of airflow, you are mostly feeling the existing air in the room moved by the air coming out of your mouth into your hand, which is not warm and will pull a little heat from your hand. However, when you increase the airflow, more air that was actually inside of your body reaches your hand, which is warm and puts a little heat into your hand.
>>8097215
surface area/volume
the air from an wide-open mouth has a smaller surface area/volume ratio than air from a barely-open mouth, so it loses less heat along the journey.
if you hold your hand right next to your mouth, both variations feel warm. your breath has travelled a smaller distance and lost less heat, so the difference between the two variations is not as apparent.
>>8097175
No. Draw the normal line in, you'll notice that the angle made in air is larger than the angle made in vacuum. Remember snell's law, because the index of refraction in air is larger than the index of refraction in vacuum, the angle in air must be smaller than the angle in vacuum. You could draw any light ray from 8 to the moon, and you'll see that the angle in air is smaller than the angle in vacuum ONLY if the light ray is initially directed above the moon.
Just aim where you see it. Light from there is bend anyway so your light will go the same path.
>>8097179
x(t) = Acos(t)+Bsin(t)
y(t) = t + (B-A) cos(t) - (A+B) sin(t)
particular solution implies A = 0 and B=1
x(t) = sin(t)
y(t) = t + cos(t) - sin(t).
I got the general solution by differentiating the second equation and plugging in it the first one after that. This gives d2x/dt2 + x = 0
you get general form of x
then you replace in second equation to obtain directly general form of y.
>>8097254
Ah clever. I didn't think to differentiate to get rid of the y. Not that anon btw.
just trying to help, I couldn't care less about this.
>>8097272
>caring
Go cry about it, you wasted two full seconds of my life scrolling.
1/2
>>8097317
2/2
Where he got + 594/7 and -662/5?
>>8097317
Dude, I responded to your first thread with the answer and an explanation. If you didn't understand my post, why didn't you ask me a question? I'm not gonna ridicule you because this is a stupid questions thread after all, but let me give you a second shot at doing this thing yourself. Here's what I responded with:
Well if each clock's rate is constant (which they should fucking specify because this problem makes no sense anyway so they should be as specific as possible), then we know that 512-312 seconds on A is equivalent to 290-125 s on B. So we know the ratio A:B is 200:165. It tells us that A is 600 seconds, so we plug that into the equality
A/B=200/165
600/B=200/165
B=600*165/200=495 s
You can also make a ratio between B and C using 200-25 and 142-92, then use the 495 s we just calculated in this ratio to find what the time for C is.
The same procedure can be used for the next part of the problem, except instead of using 512-312 for A we use 512-400 for A and 290-x for B. Then you plug in A and B into that original ratio we found and solve for x.
>>8097317
its ratios:
40/33 s on clock A to 1 s on Clock B
3.5 s on Clock B to 1 s on Clock C
40/33 s on Clock A to 2/7 s on Clock C
, 600 s on Clock A = 990/7 s on Clock C
, 600 s on Clock A = (???-your turn)
,,,similarly, other parts follow
Is biological sex a social construct?
can anybody help me figure this stuff out?
its a differetial equation problem thanks
If you know the initial and final states of a system, and you also know the change of energy. Allegedly you can know if the change was due to work or heath transfer. How?
Also if an ice cube melts its volume changes. Is the change of its internal energy equal to the heath transferred? I'm guessing it has to be equal because energy goes from outside the ice to inside the ice, so it can't be bigger or lower, only equal right?
Can I get into a decent EE PhD with good/very good GREs, multiple papers (1st author on one, lower authorship on two others), but a 3.1-3.2 gpa? I never cared that much about grades because I assumed I'd go straight into industry, but I'm doing an internship at a research lab and it's making me reconsider.
>>8097516
The first law of thermodynamics is [math] q= \Delta E +W [/math] and work [math] W=P \Delta V [/math] so you're right if you know the initial volume and final volume, the pressure, and the change in energy you can determine the work done and using the first law determine the change in heat.
>Is the change of its internal energy equal to the heath transferred?
No, refer to the first law. The heat transferred is equal to the change in internal energy plus the work done ([math] P \Delta V [/math]). Also, in the case for phase changes, there is something called the latent heat which is apart of the total internal energy [math] \Delta E [/math] but does not contribute to a change in temperature, just change in phase.
>>8097578
So if the work in the ice example is negative, the change in internal energy would be bigger than the transferred heath? This means that I can just use the sign of the work to know which one of both is bigger?
>>8097066
where can i find good math articles? specifically linear algebra and applications.
I have absolutely no clue what to do here, we weren't taught this and there's no recommended reading material.
>>8097812
Write that transcendental functions are not real.
>>8097563
Short answer: probably.
But there's no surefire way to get into a PhD program unless you have connections in the faculty. Every admissions committee thinks different things are important and there's no telling beforehand how any given one will decide.
That said, publications are a massive boost when applying for a PhD. First and foremost they care if you can do research or not, and papers are a great signal that you can.
>>8097820
Can you not post joke responses?
People who can actually answer questions are more likely to notice posts with no replies.
>>8097826
>no fun allowed, just do my homework
>>8097812
idk for a
but for b) literally write out what cosh is in exponentials and do algebra
c) is a really really easy integral
>>8097812
[math]\pi = e^{\log(\pi)}[/math] and
[math]x = e^{\log(x)}[/math]
take it from there.
>>8097812
Just express cosh and sinh in their exponential form.
What happens to the Pollard ρ algorithm when it is run with n = 35, x1 = 6? Show that
the same thing happens (for at least one value of x1) whenever n = p(p + 2) for twin primes
p, p + 2.
please halp
If time passes more quickly the further we are from a center of gravity, does time stop when we're at the center of the earth?
>>8098253
>if it gets hotter the closer I get to the stove, does it reach an infinite temperature when I touch it
Of course not
everyone who posts after this line is gay
----------------------------------------------------------
Mom, dad, I need to tell you something
>>8097826
>Can you not post joke responses?
lmao reddit kid trying to moderate 4chyn threads
I'm a bit confused about combinations/exponential sets. I understand that combinations quite literally compute the number of combinations (irrespective of the order) of a number of elements out of a bigger set of elements.
But what do exponential sets compute? i.e. [math]N^{M}[/math]
>>8098605
the number of associations between two sets.
specifically:
if you start from a set A with M elements
and you go to a set B with N elements
then you can make N^M distinct functions that associate elements of A to elements of B : for each element on A, you can choose one of N elements of B. Do that M times, and you get N^M
What is the 'physical process' behind a hybrid initial velocity? Doesn't make sense to me
>>8097254
ah, that's my fault for not wanting to differentiate any of them. lol
>>8097812
>we weren't taught this
What are the odds he means "my TA didn't do an example problem that looked just like this with different numbers :("
>>8097689
yes, but be careful, the change in internal energy can be negative, and so can the change in heat. So the sign of the work may not always tell you which of the two has a bigger magnitude.
Could anyone tell me why this is wrong and can't be done, please? (self teaching hs math)
why is it that the closer I get away from being an animal and more human, the more expensive it gets? Fuck degrees.
>>8098852
The quadratic formula doesn't work on polynomials that have their x^2 coefficient greater than 1. You have to factor in a different way.
>>8099776
generally humans trade for more money than pets.
>>8098852
sorry mate we don't know what you're trying to do.
Probably not the right place to ask this, but there doesn't seem to be anywhere more appropriate.
I'm currently a comp sci/psychology double major with declared minors in biology, writing, and cognitive science. I'm most interested in biopsychology, cognitive psychology, and neural networking. Would it make sense to drop the bio minor for a math minor? From what I've heard, biology doesn't even help that much in biopsychology. I'd prefer not to drop the writing minor, but I'd be willing to if bio actually helped me with anything.
I'm gonna ask my psychology and my comp sci professors about this, but I'd like a little bit of anon input. Thanks
>>8099786
What? The quadratic formula includes the leading coefficient.
Are there any reasonable researches proving superiority of diverse societies? Superiority defined as higher efficiency/productivity/lower crime-rate etc. not muh feelings inspirational bullshit.
>>8099999
There's research showing diversity in religious views leads to less trust and more conflict IIRC.
Tell me what to declare as my major, oh wise /sci/. My biggest priorities are making a lot of money and working from home. I'm going to double major, btw.
>Electrical Engineering & Computer Science
Could do a wide range of jobs, seems very employable and likely to give me a type of job I could do from home. Could I ever go into grad school for math with this set up?
>Math and Computer Science
Probably a narrower set of jobs, but this would likely make me more qualified candidate for the jobs I CAN do from home.
I'm more interested in math and computer science, not actually really interested in hardware beyond trying to find an open source BIOS (for fuck sake) but I can't help but envision myself making boatloads of money by going into EE and CS and keeping math on the side.
I have until fall term to decide.
If we iterate by taking a convergent sequence and fitting it into each interval between its own points, then fitting it into the intervals between the points of that sequence and so on, can the limit of that process lead to different Hausdorff dimensions based on the sequence chosen?
Let set A={a,b,c}, B={d,e}
1)How many maps f:A->A satisfy f o f = f?
2) Can you find a pair of maps f: A->B, g: B->A for which g o f = 1_{A} (identity of A)
Need help with these..
>>8100220
Also for 2) If so how many such pairs.
>>8100080
I'd go for Math & CS. If you want to go to grad school for math you'll need more math than what you'll be exposed to with a CS degree.
>>8100220
1) seems f must be bijective, thus invertible. So f^{-1} exists. so f^{-1) f f = f^{-1} f, so f = identity.
>>8100220
2) No. the range of g can only contain at most 2 elements. thus g f can't be surjective.
>>8100305
sorry, this is wrong. rethinking...
>>8100305
Wrong, f can swap two elements.
>>8100228
I'm not set on grad school, but I'd like to keep that door open.
Which ones are most useful subjects/courses to actually study?.
>>8100479
single var calc, multivar calc, lin alg, math for cs, intro to CS and prog, introduction to algorithms
>>8100305
this shows that if the range of f is 3 elements, then f(a)=a, f(b)=b, and f(c)=c.
if the range of f is 1 element, there are 3 possibilities:
f(a)=f(b)=f(c)=a
f(a)=f(b)=f(c)=b
f(a)=f(b)=f(c)=c
So that's 4 maps so far, and you are left with the range being 2 elements.
f(a)=f(b)=a, f(c)=c works
f(a)=f(b)=b, f(c)=c works
f(a)=f(c)=a, f(b)=b works
f(a)=f(c)=c, f(b)=b works
f(a)=f(b)=c, f(c)=a doesn't work
f(a)=f(b)=c, f(c)=b doesn't work
no others
Looks like 8 total
>>8100488
thx anon
Is there an oscillating function without imaginary numbers?
>>8100554
sin(x)
Re{sin(z)}
>>8100479
Most useless?
>>8100570
>without imaginary numbers
>>8100707
sin(x) doesn't have imaginary numbers in it. I know it's hard to believe.
>>8100710
Not that guy, but, while the result of sin(x) does not have imaginary numbers, an analytic expression of sin necessarily involves them. I believe is a fair complaint or at least note to make.
Mine is a little convoluted but I hope someone can figure it out, even within a rough estimate.
I have just "purchased" a home currently worth $500,000. I put $0 down when I did the deal. I currently owe $440,000 on the home. I will always be the only person paying the mortgage of lets say $1900 every month, and I will always have to split the equity 50/50 with my "investor" when I sell the property.
So being that there's $60,000 in equity in the home that at this moment technically ALL belongs to my investor, and I'm paying $1900 a month is there a point where I'll experience diminishing returns, where if I choose to keep the property and not sellI'll just be essentially paying for him to make more money and I'll stop benefiting from it? I'm assuming its the point when I've paid $30,000 into the mortgage (half the current equity) but I'm unsure.
How is consumer demand calculated?
>>8100712
>an analytic expression of sin necessarily involves them
no.
sin is just sin.
sin is a solution to y''+y = 0
sin(x) is the sum of the series (-1)^n * x^(2n+1)/(2n+1)!
If you think that somehow going through the exponential to define sin makes it more valid, think again.
So either the guy takes 30seconds to explain what he's really asking, or he won't get any valid answer.
>>8100741
I was just wondering why imaginary numbers are needed for rotations
>>8100754
Because real numbers are one-dimensional?
Science is a liar... sometimes.
So I'd spend less time doing that and more time earning God's graces.
>>8100757
Elaborate, please.
>>8100762
What would rotation mean on a line? You can multiply by -1 if you want. I must be misunderstanding your question.
Since we classify dogs differently based on their heritage (one breed is smarter/stupider/etc. than an other), is it ludicrous to apply that differentiation between interspecific organisms to humans?
(not a /pol/ shitposter, seriously just want to know)
>>8100769
What about for R^2?
>>8100776
You can accomplish rotation in R^2 with matrices. But R^2 is isomorphic to C, so it's in some sense equivalent to using i.
My personal analysis knowledge doesn't extend far enough to explain much further, hopefully that helps.
>>8100762
look at what -1 does: it takes a number on the real line and flips it a whole 180°. 5 becomes -5.
There is nothing in between.
Now imagine a number I that corresponds to a rotation of 90°.
That number would be such as I^2 corresponds to a rotation of 180°, or a negative number basically. If you want it to preserve length, you can also ask that I^2 = -1
and bam, you just got your first imaginary number: i.
If you want to go further to know what happens when you want other angles, watch this https://www.youtube.com/watch?v=oxF5VQSA4Hw
then you will also understand why e^(i*pi) = -1 is actually beautiful
With the binomial theorem, I don't understand how this part works.
It's clear that it's what gives the coefficients, but how?
>>8100793
C has multiplication and division defined.
>>8100098
Please answer.
Does it always fill up to Hausdorff dimension 1?
>>8100837
doesnt R2 also have multiplication define
>>8100819
>solve this while 4chan is ded
>"you cannot delete a post this old"
>>8100866
scaling multiplication. C is pretty much R2 with complex number multiplication defined.
What does that bar mean? The author never defined it. Honestly I don't really know what's going on with this bit:
Suppose [math]f_i \colon A_i \rightarrow Y[/math] is a function, [math]1 \le i,\ j \le n[/math], iff [eqn]f_i \vert A_i \cap A_j = f_j \vert A_i \cap A_j, 1 \le i,\ j \le n.[/eqn]
I'm having a weird parsing error, I can't see the sides of the "iff".
>>8100967
It's general notation for restricting the domain of a function to a subset.
>>8100793
>What's the difference between R^2 and C?
As real vector spaces, absolutely nothing. In fact, multiplication by any element [math]a+bi \in \mathbb C[/math] defines a linear operator on the plane given by [eqn] \displaystyle \pmatrix {a & -b \\ b & a}[/eqn]. If a+bi is on the unit circle, this is exactly a rotation! Otherwise, it's a rotation followed by scaling.
>>8098852
-4 * -2 * -3 does not equal 16. Rewrite your damn equation is ax^2 + bx + c, good lord.
can any1 post the picture where it has the diff tiers of math? from elementary math to uni
what level of math is simson line?
at what age do people usually see this?
Tried my luck at /g/ but I bet they don't use R.
Anyways I saved a lot of data frames in nested lists.
I know I can access my values with mylist[1][1][2,2]
for the value in cell 2,2 but I wanna save all [2,2]s of all nested list as a vector or list in a variable.
How do I do this?
>>8101212
in matlab, it would look like this
M = mylist(:,:,2,2)
maybe there is something similar in R (double colon basically goes through all the possible values)
>>8101232
There is something similar but it doesn't work for lists
[code]> li[[1]][[2]][2,2]
[1] 0.6235412
> li[[2]][2:3][2,2]
Error in li[[2]][2:3][2, 2] : incorrect number of dimensions[/code]
>>8097066
I say it's A for both, because your view of the moon is refracted also, so the laser will refract onto the correct path if you aim it straight at the moon. Supposing that the dispersion is the same for the laser and the reflected light off the moon.
>>8101242
you can always create your storing vector, then loop through all the elements you're interested in and store them there.
>>8100512
Not even close. There are several permutations of order two.
My landlord complains when I do any sort of cooking where the oil/liquid bubbles and sparks in a frying pan, because those splashes end up on the hob surface and kitchen wall.
Are the hob surface and kitchen wall not intended for this? Can't you just wash them with dish soap?
Is the amount of volume gained of homogeneous liquid a the same as the amount of volume gained of homogeneous liquid b after submerging an object of mass p in both? (liquid and b have the same initial volume)
>>8101498
what the fuck you never clean those?
>>8101517
I forgot, and they both haven't the same density. (aka different molecules)
>>8101517
the mass doesn't matter, it's the volume.
>>8101531
it makes sense now
only thing that changes is the mass
>>8101431
name one?
it's f f = f, not f f = id
Ann invested $80,000 in two bank accounts. One of the accounts pays 4% annual interest, and the other account pays 5% annual interest. If the combined interest earned in both accounts after a year was $4100, how much money was invested in each account?
I had this on my pre-calc test. I couldn't get it for the life of me. Asked a buddy and he said it's impossible with no solution. Before I send a stern email to my prof, I'd like some more eyes on the problem.
say [math]p \subset R[/math] is prime (R noeth., commutative with 1) and some finitely generated R-module M localized at p is free.
Then there is some f, which doesnt lie in p, such that inverting just f and its powers make M a free module..
why?
>>8101523
This is my first flat. I just cleaned them for the first time and it came off instantly.
I want to understand why my landlord thought it was a problem. I don't think they do much cooking, could be that.
>>8101714
tell them you will clean it every saturday or whatever day.
>>8100098
Please answer.
>>8101622
Take a basis for [math]M_p[/math] and take f to be the product of all of the denominators of your basis elements. That should work
Taking BC calc next year. Do I go with regular or graph paper
>>8101770
latex
>>8101731
It wasn't about that though. They thought that you shouldn't be doing any cooking where things splash outside the pan. As if it would be permanent.
>>8101585
Eh, reading is hard. I apologize.
Hey guys, how do you recommend one study for a college Biology II course? Previously I was basically taking notes based on the powerpoints provided because that in itself was a summary of the book, but its too time consuming and I don't have time to look over the notes enough to memorize the info without falling behind in taking notes for the next section so i can keep up with the class. I'm thinking of just studying the powerpoints religiously, seems like a better use of my time to directly start studying and memorizing rather than taking the time to write it down in a notebook. How the fuck do i study this shit? I'm a comp sci major so I've been dealing with maths mostly which seems less memorizing and more critical thinking.
So the real part and imaginary part of a complex function are separately represented by 2D surfaces... How is the complex function in its entirety represented geometrically?
What is the typical surface used for the Riemann zeta function, for example? Does it represent the whole of the function?
Are complex functions 4D?
Please someone, why does in log inequations a base lower than 1 govern that the sign changes?
>>8101761
can't one simply assume all basis elements to be of the form m/1 for some m in M, or am I missing something?
>>8102118
one way to visualize complex functions is via colormap plots. the brightness indicates magnitude and the color indicates phase
>>8102157
Graph log(x) for base 2 and base 1/2.
>>8097066
I have a question:
I want to use several of this motor for a robot I am building.
Do I need to buy that company's driver and controller? Or can I buy cheaper controller that has the same resolution and electrical config?
Also... does double axis controller mean it can control 2 motors?
>>8102190
SHIT forgot link:
http://catalog.orientalmotor.com/item/all-categories/pk-series-5-phase-stepping-motors/pkp564fmn24a?plpver=11&categid=100&prodid=3001062&origin=keyword
>>8102175
I want to visualize complex functions as surfaces. I haven't taken complex analysis and won't for a good while, but I'd just like to have a basic grasp on how (complex) functions are represented geometrically.
The absolute value surface leaves out important information, right? Is it the standard method of representing the function as a whole?
>>8102210
Thanks Anon!
>>8102222
waste of quads
nigga you're trying to visualize a function that has 2 inputs and 2 outputs.
Do you see how this can be difficult?
You're always going to have to add a subtle dimension, like color, to get access to a 4th (or more) dimension
>>8102157
Because a fractional log base corresponds with a negative exponent. You can see the result from the base change formula.
[math]log_0.1 x = \frac{log_10 x}(log_10 .1} = -log_10 x[/math]
>>8102234
So complex functions are 4-dimensional?
>>8102166
That would only generate a submodule of M.
>>8102250
just
imagine a function of 2 inputs that has 1 output.
your typical z=f(x,y).
That can be represented with a surface.
you use one x and one y axis for the inputs, and on z axis to describe the height of the surface.
If you add one other output, where do you want to put it lol
>>8102118
Well obviously you can't plot a function from C to C because that would require a 4D graph, but that's not how one thinks about complex functions.
You have never plotted a rotation of the plane but that does not keep you from completely understanding how it works. In the same way, you should think of complex (or at least holomorphic) functions as (complicated) transformations of the plane that locally behave like similitudes.
>>8097424
For sufficiently broad values of "social construct", every category of things that isn't a quantum field is a social construct. Planets are a social construct. (See also: Pluto, brown dwarfs, Ceres).
Obviously there is such a thing as differences between things, but there are always, always edge cases to every category and it becomes somewhat arbitrary which ones we decide are members of one category, which ones are members of another, and how many categories to divide a certain class of things into anyway.
For instance, there are people that are obviously biologically male and obviously biologically female, but intersex people (while very rare) do exist. Is somebody with XY chromosomes but who was born with a female body and a vagina male, or female, or do they get their own category? Any such categorization is inherently a bit arbitrary; you might even say the boundaries of this categorization system are constructed by society. A social construct, if you will.
>>8102257
How exactly are the real and imaginary surfaces of a complex function combined to form the geometry of the function in its entirety? Does the absolute value surface tell much about the resulting 4d surface?
I have 4 weeks until I start an accelerated Calculus 2 course. I did decently in calculus 1.
What should I do to best prepare for calc 2? It's accelerated, about 6 weeks long, so I want to go in with a head start so I don't get smashed by the first exam. Anyone have book recommendations?
I'm considering using a cheap blood substitute to raise mosquitoes, what can I use that they would actually want to suck out of a warm pig intestine sausage?
I'm not raising larvae for fish food btw, this is a pet research project of sorts and the like. I can't use blood because naturally it tends to clot and it messes with the setup, not sure about using anti-coagulants though, are those cheap or at least give me a good yield of clot-free blood?
Any advice on this one? The zero is obvious as is w0, but I'm having a hard time finding Q for the poles
>>8102844
oops forgot my pic
>>8101602
4100=.04*x+.05*(80000-x)
>>8102836
>raise mosquitoes
Why?
Why are Geotechnical Engineers such uptight cunts?
>>8102923
I'm going to attempt to instill a fear/disgust in them to anything that even remotely tastes or smells like cinnamon by basically killing off the ones that go for the sausages coated with cinnamon scent. Hopefully this fear is inherited by the offspring through epigenetics. Then all there is to it is to just switch to a cinnamon perfume and no more mosquito bites.
They already seem to dislike cinnamon, so I'm taking advantage of that.
>>8103033
breeding mosquitos to dislike cinnamon doesn't mean all mosquito's will automatically become that breed. There needs to be something about the mosquitos you are breeding that makes them more likely to survive in the real world. Killing off the ones with unfavorable traits in the lab does not mean those same mosquitos will be killed off outside the lab.
>>8103045
Well it's good that you mention that because I got you covered; I'll be designing simple 'traps' that give off co2 using yeast and heat from a simple resistance, some will smell of cinnamon and be laced with a random nasty poison or toxic chemical, others will be basically free food with no cinnamon or nasty nothing.
They will learn, anon, or they will die.
>>8103063
I still don't understand how that helps. You plan to install these traps all around the world? Because sooner or later mosquitos will find you and not give a shit about your cinnamon spray.
is there any difference between algebraic closure and topological completeness?
>>8103066
>You plan to install these traps all around the world?
Hey why not? If enough people do it it's sure to have a greater impact. For now I'll just stick to testing the idea with the local fauna and see what results I get.
>>8103033
Insects don't feel fear or disgust.
>>8103084
I don't care what feelings drive them, as long as they know to stay away from cinnamon.
I would argue against them not feeling fear though, that is like the most primal feeling to survive if you don't count hunger.
>>8103072
yes
when you take the closure of the rationals [math] \mathbb{Q}, | \cdot |_\infty [/math] with respect to the Archimedian valuation to [math]\mathbb{C} [/math] you get a closure which happens to be topologically complete, but if you go from [math] \mathbb{Q}, | \cdot |_p [/math] with the p-adic valuation you get a closure [math] \overline{\mathbb{Q}} [/math] which is not topologically complete, and so you need to perform one more step to complete to a new field [math] \mathbb{C}_p [/math]
see http://wstein.org/129/projects/hamburg/Project.pdf
>>8103117
*those should be [math] \mathbb{Q}_p, |\cdot |_p [/math] and [math] \overline{\mathbb{Q}_p} [/math] in the p-adic part
Let [math]X \subset \mathbb{A}_k^n[/math] and [math]Y \subset \mathbb{A}_k^m[/math] be affine varieties. Let [math]\mathcal{O}\left( X \right)[/math] denote the the coordinate ring (i.e. sheaf of global regular functions) of [math]X[/math].
Prove: [math]\mathcal{O}\left( {X \times Y} \right) \cong \mathcal{O}\left( X \right){ \otimes _k}\mathcal{O}\left( Y \right)[/math]
>>8103084
Holy shit I am now so in disagreement with this post! I just witnessed a mosquito begging me for mercy! She was actually very epxressive with the front legs, imagine what a guy ambushed by soldiers and begging not to get shot would look like, It's holding your arms out with your palms doing a "calm down" gesture. Now just picture a mosquito doing the same gestures when it realizes you have it cornered and there's no escape.... I tried recording other encounters but the camera can't see that close up.... gotta buy me those little macro lenses if I wanna deliver on this bullshit...
I tried on another with just the phone light and I could see the shadow of the mist of pee coming out of it's ass right before it took off.....
>>8103258
>Attempting to torture mosquitoes to prove that they feel fear
I think you are humanizing, but this is hilarious.
>>8103261
It's.... not torture, I wouldn't torture any form of life by my own will (inb4 no will), it's just scared to be eaten by my gecko or killed by my brother.
>>8102905
I'm not asking for help to solve, I'm asking can it be solved. I tried like hell and someone else took a crack and said no dice.
>>8103290
Considering you were just given the problem expressed as an equation, and that equation is clearly solvable, yes.
By the way are there any knowledgeable biologists/chemists/biocehms around to help me make the blood sausages last longer? This is a pretty warm place, I'm afraid they'll rot fast and I've no clue about proper preservatives (except for the pig intestine)(which, by the way, gross).
>>8103290
1% of mathematics is linear algebra, the other 99% is mathematicians trying to reduce more complicated problems to linear algebra.
you have before you a linear equation in one variable. I believe you can solve that, champ
Any med students know about dermatitis? My particular case is pretty much nothing but itchy peeling/flaking dry skin. Most concentrated on underarms where I also have creases of thinned out skin between "normal" skin (unsure of terminology); but also a couple of much more minor patches on face and now skin is flaking off of my balls.
Before you tell me to see a doctor, I've seen multiple useless drug-pushing fucks over the course of ~2 years and have been "controlling" somewhat ineffectively these days with corticosteroids. I initially had scrape tests done by a dermatologist before the term eczema triggered all future doctors to shut their brains off and say "lol incurable here's your script". Sucks to have meh-tier insurance.
A question I have is if this could be misdiagnosed candidiasis. If I recall correctly, I also had an "unrelated" pink patch on my chest when I first went in that was identified as yeast and solved with antifungal pills. I wonder if that was why corticosteroids seemed to have a more significant effect at first - the antifungal was the real treatment. I've never had disgusting shit like thrush for what it's worth.
I'm given a solid P which is contained between two spheres. Then given a vector field F, they want me to calculate the surface integral
[eqn]\iint_{\partial P} \mathbf{F}\cdot\mathbf{n} \ dS[/eqn]
what the hell do they mean, calculate the surface integral over a hollow solid? Does the [math]\partial P[/math] mean they want me to do it for both surfaces and then find the difference?
inb4 use divergence theorem, they want the surface integral as well as the triple
>>8103370
I'm behind you in calculus, but out of my own curiosity I ended up at a list of uses of ∂:
https://en.wikipedia.org/wiki/%E2%88%82
It seems to be the boundary of of the solid P. See its usage as boundary here:
https://en.wikipedia.org/wiki/Reynolds_transport_theorem
>>8097066
What's wrong with me. I had a bunch of open assessments/projects/reports whatever and a bunch of exams this year.
For the open assessments -- which are basically sort of a report or problems to solve but you have more time -- I always get the highest mark or around that mark
For closed assessments -- which are just exams where you have like 2 hours to finish -- I almost never get the highest mark, I just get decent marks.
Am I just too stupid and I get good marks for the open assessments because I invest more time than everyone else, but in the exam we all have the same amount of time and smarter people get better grades? I'm pretty sure I was quite prepared for the exams.
I haven't had all the script viewings yet, but for the one that I went to, I lost marks for calculation mistakes, not paying attention, not having the units properly, etc. Am I just too disorganised in the exam? How do I get better I'm frustrated as fuck. This is not meant to be a humble brag or something, I study A FUCKING LOT
>>8103370
>then find the difference?
no, you are supposed to find it for both surfaces then add. Make sure your normals on the two spheres are opposite though, i.e. have them all pointing out of the solid.
>>8103370
[math]\partial P[/math] is boundary of the solid [math] P[/math]. But becouse the integral is a flux integral, you can use those spheres to help you. The outflow of F is same with [math]\partial P[/math] as with [math]H[/math] where [math]H[/math] is the surface, oriented outwards, of the outer sphere.
How many maps f: A->A satisfy f o f = f
where A={a,b,c}
I do not understand how this is no different than asking how many maps there are for f:A->A which is 3^3=9.
Can anyone explain this?
>>8103667
> I do not understand how this is no different than asking how many maps there are for f:A->A which is 3^3=9.
Say f is a map such that
1 -> 2
2 -> 3
3 -> 1
Thus the composition f o f is
1 -> 3
2 -> 1
3 -> 2
which is not equal to f (right?)
>>8103667
If f o f = f, then for all x, f(f(x)) = f(x). In other words, applying the same map twice is equivalent to only applying it once. Pretty sure that's just the identity in this case.
Only saying pretty sure because I should prefix that I'm technically behind you in math lel.
>>8103377
reread your calc 1 book from cover to cover. Do example problems if you really want to be prepared. Also, what book did you have for calc 1? Usually the book you get will actually contain material up to calc 3 and you just use the same book all 3 semesters, but yours may be different.
Just try to have a good understanding of the foundation material, and try to train yourself to have an intuition about it, and you'll be fine for calc 2. good luck.
>>8103667
What you're asking for are the permutations of A that satisfy fof=f.
Let f be such a permutation.
Since all permutations can be decomposed into cycles, the condition fof=f implies that f decomposes into cycles of length <=2.
Since CardA=3, f is decomposed into a cycle of length 2 and a cycle of length one, or three cycles of length one.
That makes four permutations.
Explicitely, those are :
Identity
f1 :a->a
b->c
c->b
f2:a->b
b->a
c->c
f3:a->c
b->b
c->a
>>8103702
I'm kinda curious myself now.
If f has an inverse
f = f^{-1} o f = I
So now you just have to check the cases that don't have inverses.
My gut tells me it's just the four *identity and 3 constants), but I have no idea how to prove that
>>8103679
> Pretty sure that's just the identity in this case.
constant functions work
>>8103718
(f1 o f1)(x) =/= f1(x) for x in {b, c}
Similar for f2, f3.
You found f o f = identity.
>>8103726
Yeah my bad, I can't fucking read
>>8103574
ok thanks -- subtracting the inner surface integral with the wrong normal turns out to be the same as adding it with the right one, since the correct normal is the negative of the one I used. I thought my problem was with my surface integration but maybe not ...
basically my vector field, when parametrized spherically, has values of r^2, so because the normal contains r, the dot product gives me an expression with r^3 and integrating wrt r gives me something with a coefficient of r^4. But then when I do the divergence of the field, the r^2 sticks around, so when the Jacobian multiplies the whole thing by r^2 I'm left with with a coefficient of r^4, which when I integrate becomes r^5. Obviously these two can't be equal because they're in different degrees. So I'm scratching my head ...
Sorry if that doesn't make any sense but any help would be appreciated. (The field is <z^3,y*(x^2),z*(y^2)> if that makes it any clearer about why the divergence has r^2 values.)
>>8103723
>>8103718
Thanks. Reading through your responses.
What does it mean for a permutation to be decomposed into a cycle? What is a cycle?
How do you know that the condition fof=f implies that f can be decomposed into a cycle of length <=2? Or Since CardA=3, f is decomposed into a cycle of length 2 and a cycle of length one, or three cycles of length one => 4 permutations?
Also what am I missing here:
where -> represents mapping f on A
A={a,b,c}
fof=f,
a->a->a
b->b->b
c->c->c
a->b->c
b->c->b
c->b->c
a->c->a
b->b->b
c->a->c
Can you do something like?
a->a->a
b->a->a
c->b->a
Is this all the mappings that satisfy our conditions? What are we missing?
where -> represents mapping f on A
A={a,b,c}
fof=f,
a->a->a
b->b->b
c->c->c
a->b->c
b->c->b
c->b->c
a->c->a
b->b->b
c->a->c
Can you do something like?
a->a->a
b->a->a
c->b->a
a->b->b
b->b->b
c->b->b
a->c->c
b->c->c
c->c->c
If so then this is 6
>>8100512
We need
f(f(a))=f(a) and
f(f(b))=f(b) and
f(f(c))=f(c).
There are 10:
(f(a),f(b),f(c)) = (a,b,c)
(f(a),f(b),f(c)) = (a,a,a)
(f(a),f(b),f(c)) = (b,b,b)
(f(a),f(b),f(c)) = (c,c,c)
(f(a),f(b),f(c)) = (a,a,c)
(f(a),f(b),f(c)) = (b,b,c)
(f(a),f(b),f(c)) = (a,b,a)
(f(a),f(b),f(c)) = (c,b,c)
(f(a),f(b),f(c)) = (a,b,b)
(f(a),f(b),f(c)) = (a,c,c)
Check, for example, if
(f(a),f(b),f(c)) = (a,a,c) then
(f(f(a)),f(f(b)),f(f(c)))
=(f(a),f(a),f(c))
=(a,a,c) =(f(a),f(b),f(c))
There are two capacitors in series, one is 4F and the other one 2F, with a voltage of 120V. How do I know the voltage in one capacitor?
I know that V = V1 + V2, but that still doesn't tell me how much in V1 or how much in V2.
>>8102292
>How exactly are the real and imaginary surfaces of a complex function combined to form the 4-dimensional geometry of the function in its entirety?
Surely this is something very simple?
>>8097066
what's the point of writing this in scientific notation: 2.528243e+06
to my understanding, this would be 2,528,243 in decimal notation, and scientific notation is meant to make it easier to write but it doesn't apply here
>>8104035
The order of magnitude immediately gives you an idea of the general size of the number without having to read/write the whole thing.
So like "e+06? oh that's something million."
>>8104056
thanks that's helpful. do you know whether there's a particular reason why it's "06" instead of "6"? i was thinking it may be to keep consistent among magnitudes > 9 such that they all have 2 digits, but not sure
>>8104059
It'll just be a convention thing, heck I rarely ever see it written as e outside of excel spreadsheets, it's written as x10^whatever most places I read it.
But yeah the general idea behind it is that since our number system is in base 10 it's usually helpful to indicate the power of 10 that your value lies in the vicinity of to get an idea of how big it is. Makes it pretty easy to check if your predicted value is absurdly large/small.
>>8103971
First, you need to work out the charge. Using the relation Q = VC, where C here is the total capacitance. Do the reciprocal adding (1/C_tot) = (1/C_1) + (1/C_2) to get that the total capacitance as 4/3 F. Hence the total charge is 160C.
The key idea is that the charge is the same for both capacitors in series, and hence you can now analyse them individually using Q = VC again. You'll find that you get 40V and 80V for the 4F and 2F respectively.
To check: 40 + 80 = 120 as expected.
>>8103779
What is an easy way to churn through these and figure it out?
>>8102222
>I want to visualize complex functions as surfaces.
Look into algebraic curves.
I know the total area of this polygon.
i know the area of the light blue polygon.
i also have information (the coordinates) of all vertexes in this polygon.
how can i determine the areas of A, B and C?
pic related
>>8104317
https://en.wikipedia.org/wiki/Shoelace_formula
>>8104324
yeah i used that to calculate the area of the lightblue polygon.
but i want to calculate the area of A, B and C polygon.
>>8104327
Apply it again to the appropriate subsets of points?
>>8104334
the thing is, i'm suppose to write a program to calculate A, B and C given the vertexes of the polygon.
in the input they give the coordinates of the lightblue polygon and i'm expected to find the areas inside the total polygon, that is A , B and C.
If the universe expands faster than the speed of light, does that mean that no spacecraft could reach our solar system? Like is there a paradox in play that says no craft going slower than the speed of light can reach another galaxy?
>>8104338
bump
>>8104382
>As of March 2013, NASA estimates the rate of expansion is about 70.4 kilometers per second per megaparsec.
The speed of light is 299792.458 km/s. Expansion faster than the speed of light thus happens at a distance of 4258 megaparsecs.
Here is a list of galaxies within 3.6 megaparsecs:
https://en.wikipedia.org/wiki/List_of_nearest_galaxies
>>8104338
You can first find the concavity of any test point:
http://stackoverflow.com/questions/10673740/how-to-check-if-a-point-x-y-is-inside-a-polygon-in-the-cartesian-coordinate-sy
Then, simply go through each point and assume it's not in the original polygon. Test if it's interior or exterior, and if it's exterior, you keep it, else, make a new polygon without it. You might have to play with the recursiveness to make sure you don't just end up eliminating all the points. Something like poly A might be tricky. After you obtain a completely convex polygon, it's (probably) the larger polygon, then you can just subtract areas.
How one proofs that sin(n^2) (n is a natural number) does not have a limit as n ->∞. It is very easy to show for sin(n), but I'm stuck for sin(n^2).
If you want a person's brain to believe several days have passed, when in reality maybe an hour or two has passed, do you speed up its perception of time or do you slow it down?
Are there any drugs capable of doing either of those things?
>>8104490
>speed up its perception of time
http://www.wikihow.com/Speed-up-Time
>>8104490
>Are there any drugs capable of doing either of those things?
I mean, if you give them enough acid you can probably convince them of it
>>8104428
Not sure, but maybe a proof by contradiction?
Assume that such a limit exists, then test the function to see whether it obeys the behaviour. In particular, could you examine the difference between sin((n+1)^2) and sin(n^2). If it reaches a limit, the (absolute value) of the ratio between these terms must decrease (necessary condition).
If you tried some addition formulae for trig functions, could you make headway?
Part of me wants to say that if you've proved it for n, then surely it follows immediately for n^2 since the squares form a subset. But that sounds really tenuous.
>>8104490
synthetic cannibinoids spec happy shaman herbs.
makes 15 minutes feel like multiple hours
>>8104644
>synthetic cannibinoids
Also can seriously fuck your shit up.
>>8104382
>>8104401
>>8104413
The universe is expanding everywhere (the classic analogy is that of a surface of a balloon). As such, there are objects far away that are receding from us at faster than the speed of light. Nothing by itself is moving > c, but their relative speed from us is > c*
As a corollary, light from objects leaving these places will never reach us. In posh terms, they are outside of our past lightcone (and have never been in it). Likewise, spacecraft from these places cannot reach us either.**
But nearby spacecraft could still reach us, because the expansion rate is fairly modest when close by. More importantly, for gravitationally bound systems, this expansion is not really happening at all. And we are only ever likely to be able to travel within the galaxy, so it's not an issue.
Is that what you were getting at?
*Think of two cars approaching at 100mph. Their relative speed to each other is 200mph, but nothing is going this fast - you can prove this by recognising that almost all cars are not physically capable of 200mph.
** There is a bit more subtlety here. If the expansion is decelerating or under certain other conditions, light from such objects will eventually reach us. See this paper: http://arxiv.org/abs/astro-ph/0310808
>>8104631
>Part of me wants to say that if you've proved it for n, then surely it follows immediately for n^2 since the squares form a subset. But that sounds really tenuous.
This doesn't work. Obvious example is the sequence defined by
a_n = 0 if n is not a square
a_n = 1 if n is a square
for squares it's just 1 1 1 1 1... but the parent sequence has no limit
>>8104631
>Part of me wants to say that if you've proved it for n, then surely it follows immediately for n^2 since the squares form a subset. But that sounds really tenuous.
I think it's valid for a continuous functions but definitely not for discrete.
>>8104428
I don't see why it's more complicated than sin(n), a similar argument works
>>8104827
What argument did you use for sin(n) then, and how do you adapt it?
>>8104837
Nah never mind, bad heuristics, it's trickier than I thought. I'll think about it.
The proof I had in mind was considering the sum sin(n+1) + sin(n-1) = 2sin(n)cos(1), which would imply, if (sin n) were convergent with limit l, that 2l = 2lcos(1) and this l = 0. But of course this would not work here
There are instruments to measure electricity and stuff right? Some are based on the heath generated, and some others are based on the magnetism generated. What are the names of those two types?
What does the sum of the reciprocals of squares of primes being 0.4522474200... tell us about primes when compared to (pi^2)/6? Is it a totally useless sum?
It's about 27,5% of (pi^2)/6.
>>8104338
oooh.. you mean you need to find the convex hull? Look up convex hull.
Basically, in 2d, you can start with the point with the smallest y component. draw a horizontal line through it. imagine rotating line counter clockwise until it intersects another point. that's the next point in the hull. rotate again to find the next point... etc ... until you get back to where you started
How would I get the Lagrarian of a path I already know under a constant gravitational field? The potencial is pretty obvious but the velocity would be in terms of what?
Why do I get 12V? As far as I know the 3.7 ohm should make it less. Is the software wrong or is it me?
What's better:
Math and physics double major with CS minor or math and Cs double with physics minor
>>8097066
Supposed to use contour integration, pls halp. Not homework btw, just want to lrn2 contour.
>>8105005
Plug your metric into the geodesic Lagrangian?
>>8105227
what's the trick? poles are at z=2 pi i k for non-zero integers k.
>>8100080
If you're actually interested in making money go EE. If you're heavily interested in math, double major in it.
Will it be hard? Yes.
Will it take longer because of non-overlapping classes? Yes.
Will you be doing what you want and be ready to enter the work force AND possibly go to grad school? Yes.
>>8105174
Unless you are going to a top university, you'll just get a washed down paper with whatever of those options.
Just go with whatever you like best and focus on that. Take grad courses when you can and just try to keep your curiosity alive.
>>8105227
[math]\int_0^{\infty}\frac{x^3}{e^x - 1}dx = 6\zeta(4)[/math]
>>8105496
Cleo pls share steps.
[math]X[/math] and [math]Y[/math] are independent continuous random variables with Gamma distribution. How the FUCK do I prove that
[eqn] \mathbb{E} \left( \frac{X}{X+Y} \right) = \frac{ \mathbb{E} ( X ) }{ \mathbb{E}(X + Y) } [/eqn]
Is it so that despite functions from C to C being 4-dimensional, the geometric aspect is usually always bypassed by using alternative representations for the additional dimension? Why isn't the 4D structure commonly studied and appreciated? Does algebraic geometry describe the actual structure of complex functions?
>>8105818
remember that the joint distribution of (X,Y) is just the product of the 2 distributions thanks to indipendence, then calculate the 2 values
not sure if this is easy tho
>>8104428
just observe that there is a subsequence sin(n_k ^2) that is strictly higher than a certain value c (for example, c = 1/2) and another subsequence that is strictly smaller than 0
therefore the limit can't exist for the sequential characterization of limits in R
not sure how is to compute 2 of those explicitly but it's pretty easy to observe
>>8105818
Recall that if X has shape parameter [math]\alpha[/math] and rate parameter [math]\lambda[/math], i.e. [math]X \sim Gam(\alpha,\lambda)[/math] then [math]\lambda X\sim Gam(\alpha,1)[/math].
If X is independent of [math]Y \sim Gam(\beta,\mu)[/math] then [math]Z = \frac{\lambda X}{\lambda X + \mu Y}[/math] has a Beta distribution, and using the standard properties of the Beta and Gamma distributions we can immediately find that [math]E[Z] = \frac{E[\lambda X]}{E[\lambda X] + E[\mu Y]}[/math].
When [math]\lambda = \mu[/math] i.e. both X and Y have the same rate parameter, then they cancel out to give your result. I don't think it holds when [math]\lambda \neq \mu[/math] (I could be wrong though).
>>8105417
I subbed in for z=e^x and got i*[(ln(z))^3/(z-1)dz] in the integral. Which I can't do, but tells me there is a pole at z=1. Am i gonna have to finally suck it up and learn Laurent series?
How do I find a specific digit of pi.
I found : Pi = SUMk=0 to infinity 16-k [ 4/(8k+1) - 2/(8k+4) - 1/(8k+5) - 1/(8k+6) ]
But I have no idea what any of it means.
>>8097066
How can the median be a number that is not x.5 or x.0 ? Like how can the decimal be different than .00 or .5
>>8105971
Thank you based anon. Now I will try to understand it.
Can somebody explain the Bloch sphere to me? Specifically this formula:
[eqn]w = cos(\frac{\Theta}{2}) \left| 0 \right \rangle + e^{j\varphi } sin(\frac{\Theta}{2})[/eqn]
I don't understand why it's theta/2 and not just theta. With the limits given (theta = 0 to pi), surely this limits the vector to the upper hemisphere.
>>8106056
EDIT: should be
[eqn]w = cos(\frac{\Theta}{2}) \left| 0 \right \rangle + e^{j\varphi } sin(\frac{\Theta}{2}) \left| 1 \right \rangle[/eqn]
Forgot the |1> at the end
>>8106061
That looks suspiciously like the quaternion version of Euler's rotation theorem.
Every rotation [math] \mathrm{q} [/math] can be described by an angle [math] \theta [/math] and a rotation axis [math] \mathbf{\hat{u}} [/math], so that
[math] \mathrm{q} = \cos \left(\frac{\theta}{2} \right) + \mathbf{\hat{u}} \sin \left( \frac{ \theta}{2} \right) [/math]
https://en.wikipedia.org/wiki/Rotation_formalisms_in_three_dimensions#Quaternions
Then you can rotate any vector via this rotation by quaternion multiplication
[math] \mathbf{v}' = \mathrm{q} \otimes \mathbf{v} \otimes \mathrm{q}^{-1} [/math]
I haven't seen a derivation for the [math] \frac{\theta}{2} [/math], yet though.
>>8105451
It's so hard to pick. Math + Physics is where my interest at academically, but CS is the type of job I want (cozy programming). And I do want to keep the grad school door open, and I know that I very likely would never self study math or physics to the point I'd like to get to.
So idfk, I know with CS a degree isn't always necassary so maybe I can get away with this.
Let's say I have a hollow sphere and smaller solid balls of the same size, how can I find out how many balls I could fit inside the sphere?
Not homework btw, I'm just wondering how many Ceres I could fit into a Luna, something like lotto balls.
