Recent content by kisengue

Thank you both for your answers! My specialization is scientific computing - I lack quite severely in "hard" engineering skills, except that I'm getting quite good at programming. Not even close to the programming skill of a comp.sci engineer though.

Your question is kind of a non-question - your f(x) is not mathematically smooth, that is, it is not in C^inf. It is only in C^0 or D^1.

Hello everyone! I am currently studying Engineering Phyics at Lund University in Sweden. I have one year left, which will give me a master of science degree with a specialization in simulation and scientific computing. Thing is, people have always been telling me that Engineering Physics is a...

I'm an almost finished engineer, and have started working (as an engineer) on the side of my studies. I do what the other engineers do, no more and no less. My discipline is engineering physics with a specialization in simulation (so lots of math and numerical analysis) and I work for a large...

The proof (sorry for not linking it immediately). Fredrik, I'm asking the first of those two - the second I understand. Micromass: I didn't think of that... but of course. Of course. Damn it. Now I get it, I think.

So, I've found the result that orthonormal sequences in Hilbert spaces always converge weakly to zero. I've only found wikipedia's "small proof" of this statement, though I have found the statement itself in many places, textbooks and such. I've come to understand that this property follows...

Hello! I've found this paper, wherein page 33 states that the reverse Poincaré inequality gives \forall v \in H^1_0(\Omega) , \|v\|_{L^2(\Omega)} \leq C(\Omega) \|\nabla v\|_{L^2(\Omega)} This I can follow - it gives a norm equivalence between the norm of a vector and the gradient of its...

Oh... you're right, of course! That's helpful. But that only reverses the direction of my final unit vector, it still has the same magnitude... The problem is marked as "more difficult" in the book, and it doesn't seem all that hard so i guess there's something that i don't immediately consider.

Hmm... the way I've done it thus far, and is described in my mechanics book, is to form the vector from A to B by subtracting A from B... so AB in the problem would be B-A=(4,0,0)-(0,0,3)=(4,0,-3), right? Or have i left something out? Also, how would this change the magnitude of anything? I...

This should be simple, I've already solved several problems just like this one but it won't come out right however i try... apologies in advance for non-native english. Homework Statement In a 3-dimensional coordinate system, a hook is placed in A=(0,0,3). Two lines connect the hook down to...

1. You are not wrong. You have x^2sin(-x). But sin(-x)=-sin(x), and so x^2sin(-x)=-x^2sin(x). 2. f(-x)= (-x)3 + cos(-x) = -x3+ cos x = neither 3. (-x)sin3(-x) frankly i have no clue how to do that one. Again, sin(-x)=-sin(x)...

This is indeed a problem of conservation of energy. As the crate collides with the spring, at some point all the kinetic energy of the crate will have been transferred to the spring. The mathematical expression for energy stored in a spring is E=ky^2/2 where k is the "spring constant" (don't...