Recent content by jacobrhcp

Yes! of course, you are very right, I am very sorry I did not write them down in the initial problem description, I've edited them in. Without these it's all nonsense. Though it's no assignment, it is a purely mathematical problem. (in fact if you're interested: it is was mathematical model...

Hi! I have a system of four differential equations: \dot{x}(t)=Ax(t)+a where A\in R^{4x4} and a\in R^{4} are known and, x(t)\in R^4 \forall t>0 EDIT: the constraints I have on these differential equations are: x_1(0)=x_{1,0}, x_2(0)=x_{2,0}, x_3(T)=x_{3,T}, x_4(T)=x_{4,T} I know...

Now that I reread, I am sorry for how poor this question was phrased. What I mean is indeed the four-dimensional box: \{(x_1,x_2,x_3,x_4)\in ℝ^4|a_1\leq x_1 \leq b_1, a_2\leq x_2 \leq b_2, a_3\leq x_3 \leq b_3, a_4\leq x_4 \leq b_4\} And what I meant is not the cross product of the points...

Okay, I'm a bit confused by your problem. you mean, taking a specific example, for instance f(x,y)=(xy)^3? Then, if you know for instance f(x,y)=14 and y=pi/2, that x should be \frac{14^{1/3}}{pi/2}. Using that you can then see that f(x,y)=f(y)=(\frac{14^{1/3}}{pi/2} y)^3. Trying the...

Hi! I stumbled upon something I need to implement my problem in a computer. Because I think its actually fun to puzzle on, I thought it might be nice to post it here. The problem is this: If you have a 4D hypercube, (a_1,b_1)\times(a_2,b_2)\times(a_3,b_3)\times(a_4,b_4), what is an easy...

A former professor of mine made a page dedicated to what you need to know to become a good theoretical physicist, along with learning material and everything, all learning material is available online. It is truly a good place to go for physics. The other sciences I know nothing of, so can't...

Hi, Currently I'm finishing a masters' degree in Econometrics in Holland, I posses a physics bachelors, and did a ton of mathematics courses on the side during, my studies. Here it is common to do both a bachelors and a masters, and after that either start work or do a PhD. I feel like I...

Hey! If you're only looking for the answer, you can use this. For methodology, you can do two substitutions: first v=a+b\theta Then you need to make a second substitution v=b*sinh(u). Don´t forget the derivatives. For more information you can visit this topic...

verifying: if you have a solution to a problem (like: can you solve a particular version of TSP in less then k meters?), can you then in polynomial time in the input parameters (in this case the number of nodes and arcs in the TSP network) check if it is indeed a solution that is shorter than k...

So maybe when going from 2 to 3, you don't need to use evenness but 'divisible by three' ;)

If you want to generate random numbers you of course first need to think about what distribution you want. If for instance, which is maybe what you mean, you want to draw random numbers uniformly from an interval (a,b), then there are several algorithms that can do so. For instance linear...

Thank you jtbell, but I'm not sure that is what I meant. Even if I write a function to do something like this, I still have to call the function again and again. I was wondering if there is a way to make some global statement like: if anywhere at any point, the user input to this program is the...

I read your tutorial, and liked it! Now I am writing a text-based adventure game. I was wondering, though. If someone types something like 'help' or 'exit game' or something, I want to always give the same reply to that. How do I do that without typing something like getline(cin,a)...

I have Zeidler's applied functional analysis, which I liked at the time. For me, aside from calculus and other computational courses, some analysis courses were also prerequisite. If you are just interested in the physics, i.e. Euler Lagrange equations, Hamiltonian dnamics etc. I can...

First, note that the limit intuiteively means that if you go really far from the origin, g becomes almost zero. if you first suppose by contradiction the limit does not hold and g(x,y)=g(x(r,\theta),y(r,\theta)), then there must be some constant angle theta along which g_{\theta}(x(r),y(r))...