# Search results

1. ### Prove that f(n) = n * log (n) is O(n(1+sqrt(n))).

I don't know where to start to solve for c.. that is my problem... I don't understand where the 1 comes from... I know O(logn) < O(sqrt(n)) so I can get that but where is the (1+srt(n)) comes from?
2. ### Prove that f(n) = n * log (n) is O(n(1+sqrt(n))).

yes well I don't know how to go from f(n) to g(n)... the examples I have seen were just that you would multiply so part of f(n) until you could group everything together to get c* g(n) but this time I don't see how I can multiply anything to get anything that looks like g(n)...
3. ### Prove that f(n) = n * log (n) is O(n(1+sqrt(n))).

f(n) is O(g(n)) if and only if there exists an n_0 part of natural numbers and a constant C that is part of rational numbers for which f(n) <= that c*g(n) for all n >= n_o I know the def just don't know how to get g(n)...
4. ### Prove that f(n) = n * log (n) is O(n(1+sqrt(n))).

Homework Statement Prove that f(n) = n * log (n) is O(n(1+sqrt(n))). Homework Equations n/a The Attempt at a Solution I really don't know what to do else I wouldn't be here :? Some hints would be appreciated!
5. ### Vector field

TO DICK. F=(x*i, y*j) DIV F = d/dx(x) + d/dy(y) = 2 which means it goes outward and not to the origin... // EDIT F=-(x^2 + y^2)^3/2 * (x*i, y*j)
6. ### Vector field

F=k*(x^3*i,y^3*j), k<0 ? Is this good then? // I did not mean inversely.
7. ### Vector field

Homework Statement A particle is attracted toward the origin by a force proportional to the cube of it's distance from the origin. (...) What would be this Force equal to (in xy plane)? The Attempt at a Solution So distance is Sqrt[x^2+y^2]... and from here I don't know what to...
8. ### Nonlinear ODE

wow I'm so stupid... dy/dt = y^(1/2) dy/y^(1/2) = dt 2y^(1/2) = t + c y^(1/2) = 2t + 2c y = 4t^2 + 8tc + c^2 thanks
9. ### Nonlinear ODE

Homework Statement I have to find the solution of (1) and show that it is not unique if y(0) = 0. I can prove it is not unique by using Picard's theorem but I don't know how to find the non trivial solution. Homework Equations (1) y(t)' = Sqrt(y(t)) The Attempt at a Solution I...
10. ### Complex derivatives

e^ix first i*e^ix second i^2*e^ix e^-ix first -i*e^-ix second i^2*e^-ix p.s. I've read about the Cauchy-Riemann equation but just not sure how to apply it... should I split the exponential in a sin and a cos? p.s.s. There are probably rules, like exponential function are always derivable or...
11. ### Complex derivatives

I have to solve an ODE with variation of coefficient technique. It's pretty easy but I have no clue what is the first and second derivative of e^ix and e^-ix.
12. ### Weighted lest square fit

pdf PDF of latex file.
13. ### Weighted lest square fit

Homework Statement I have a project for one of my class and I have been given a sheet to do the statistical analyst of my data. I am not convince this sheet is proper and I need someone to look over it it. I don't understand where my Delta R goes... Homework Equations \chi^2...
14. ### Number if rational iff it has periodic decimal expansion

Thanks... that was kinda easy but I guess you just need to know it. Btw good job, this forum is a great ressource :P
15. ### Number if rational iff it has periodic decimal expansion

Ok well I guess my intuition was bad. I made a few search on books.google.com and found a couple of proofs. One is pretty easy and I actually though of that solutions before but didn't know how to generalise it. My only problem now is that I'm not familiar with one notation in the proofs. I...
16. ### Number if rational iff it has periodic decimal expansion

My teacher gave us as excercices this: I'm pretty certain you have to prove it by contradiction, but I don't get how to represent to periodic decimal expension in a proof? Any hint is welcome, thanks in advance.
17. ### Courses Choice of course Phys-Math (McGill)

Hi, I'm going into the Joint Honours Program in Mathematics and Physics @ McGill next session... I'm seeking for help on what course to take... (also how to take them...using minerva???) I'm new to all that university stuff... not too shure how it works.... here is the list of class...
18. ### Effect of distance and temperature on tunnel current

Hi, I'm studying the effect of distance and temperature on tunneling current and I need to find information about it before... so if you guys can point me out links or articles... or just tell me what you guys know about it... I know the distance/current is an exponential function but I can't...
19. ### Circuit of a Scanning Tunneling Microscope (STM)

I know that but I want to know more in debt to what i have to adjust them. Are you shure it wouldn't work? It looks it would work by looking at this software site (http://polly.phys.msu.ru/~zeld/oscill.html" [Broken]) but I can't tell... I was more scared about amperage or frequency of the...
20. ### Theory of a Scanning Tunneling Microscope (STM)

Hi, for my integration class I am building a scanning tunnelling microscope (STM). I found some interesting designs and I choose the cheapest one (students are poor) witch uses a unimorph disk. Here is the STM design I plan to build: http://www.geocities.com/spm_stm/". For my class I need to...
21. ### Circuit of a Scanning Tunneling Microscope (STM)

Hi, for my integration class I am building a scanning tunnelling microscope (STM). I found some interesting designs and I choose the cheapest one (students are poor) witch uses a unimorph disk. The circuits are not that hard to build but I also need to understand them. I have some knowledge in...
22. ### Why is the constant 5?

1/2mv_o^2=5/2mgr v_o^2=5gr v_o=\sqrt{5gr} w00t
23. ### Why is the constant 5?

Alrigth we had a lab were we had to find out what is the initial speed to give a particle to go through a vertical loop with no friction (like a rollercoaster) the equation we found was this : V_o=\sqrt{(c*G*r)} V_o = initial speed c = constant G = 9.8 m/s^2 r = radius of circle If you...
24. ### Schools University & Physics

can someone tell me what is undergraduate & graduate & then whats next before PhD ? I live in Quebec & our system is different... not only because it's french bus also because after high school we got cegep before university... here you have : High School wich is grade 7 to 11 Then CEGEP...
25. ### Schools University & Physics

well then wich one is seen as the best in Canada... US = MIT CAN = ? I was wondering how hard it is to get into MIT ... If I got to mgill & get good grades can I get in MIT for graduate... how good do you have to be to get a scholarship to MIT? I don't know crap about university's & the...
26. ### Schools University & Physics

humm ok I'l try that... so whats are the best university's for Physics in Canada.. Waterloo & Toronto ?
27. ### Schools University & Physics

What ? Ok... thanks for the info but is Mcgill any good or any university in Quebec? or is Queens any good as I'm a sailor & it would be great to study & train in Kingston.... Also I'm not too familiar with the english terms when you say graduate school thats after completing what we...
28. ### Schools University & Physics

Alright well I won't be applying for university till next year but I was wondering whats best to do... I was thinking to go McGill University (http://www.physics.mcgill.ca/ ) in Montreal as it is closed to me but is it better to like go in USA or in a foreign country to start off or I'm I better...
29. ### Usenet forums: sci.physics.strings and sci.physics.research

is that good or bad ? (being compared to m\$) ... that is the question
30. ### PF Member Photo Thread Archive

well here a 2 pretty recent pictures for your pleasure ladies :) one I'm all clean other I got my "dirty" look anyways thats it http://img211.exs.cx/my.php?loc=img211&image=me27uu.jpg http://img211.exs.cx/my.php?loc=img211&image=me5bw.jpg