3d Definition and 1000 Threads

I believe this is the correct place to post this as I believe I'm going to need to solve this as a linear system, however I suppose it might be solvable using trig as well. However, I've been at it for a while and I'm out of ideas and I think I'm missing something silly. Consider the...

Hi. I have a set of samples with small white gaussian noise that form a small part of an ellissoid in 3D space. I'm looking for a way to find the center and the axes directions of the ellipsoid that best fits these samples. This is an overdetermined problem with much more 3d points than...

i don't really understand the dirac delta function in 3D. is it right that integral of f(r)d3(r-a)dt = f(a) where a = constant ,r is like variable x in 1D dirac delta function? so why when i have f(r')d3(r-r') , it picks out f(r)? where r is now a constant and r' is a...

Homework Statement The degeneracy of the nth level above the ground state for a three dimensional harmonic oscillator is (n+1)(n+2)/2 where n takes values n=0,1,2,... A gas of N non-interacting identical lithium atoms (mass 6amu) each having spin1/2 is confined in a 3d harmonic potential...

Hello, I am trying to model a basic automobile suspension arm in 3 dimensions. The model consists of basically a triangle made up of 3 vectors a, b, and c. Vector a is "ground" and magnitude and direction is known. Magnitudes of vectors b and c are also known. So, I can write the following...

Was just wondering if anyone here has tried 3D programming. If you have, what language did you write in, what difficulties did you have, and what did you find interesting about it? As of now I know of Direct3D and OpenGL, but, if I'm not mistaken, you can use different languages to write...

I'm not sure if this is the best place to post this, if not please point me in the direction I should go. I'm doing robotics research with a professor who told me to study a few different things. One was to find some papers on plane extraction from 3d laser data. Can anyone give me the name...

Homework Statement So have this theorem defined for transforms on the Fourier kind, and hilbert spaces, on R2 The theorem sets bounds for norms of the functions and the transforms in the hilbert scale I have the proofs for the 2D case given in my lecture notes Problem: Generalize the...

Hello, I read an article about a year or two ago and I cannot remember in what magazine I read it, so I was hoping to generate some leads by reaching out. I want to find it because my professor wants to see it as well. The article was about a team or group of physicists, at a certain...

Homework Statement how to find FA, FB, FC, FD in 3D equiblirium static? Homework Equations W1 = 500kg http://www.flickr.com/photos/djaguank/5450648168 distance (see at image) if you can't see the image, please follow this link http://www.flickr.com/photos/djaguank/5450648168...

Hello, I'm having trouble getting started on this problem. Here's the question: [PLAIN]http://img810.imageshack.us/img810/2464/ee323assn3q3.jpg My issue is in setting up the governing partial differential equation in 3 dimensions. What I've tried so far is setting du/dt equal to the...

1. Three guy wires hold a pole BO as shown. The resultant R of the forces due to the three wires has a magnitude of 1000-N and is directed on the pole BO. Force F2 and F3 have a magnitude of 400-N and 500-N, respectively. The distance from point A to point D is 5-m. Find the tension in cable...

Hello! First post here at the forum. I am a member of the underwater robotics team at my school, and I have been put in charge of building the arm. I won't get too specific about the design of it, but it will include gears, motors, and stuff in between. Luckily enough, my school owns a 3D...

Homework Statement For a system consiting of a single particle of mass m in a box of volume L^3 (Lx = Ly = Lz = L) develop a relation between the number of accessible states, Ω(E) and E Homework Equations E = ((π^2ћ^2)/(2mL^2))(nx^2 +ny2 +nz2) The Attempt at a Solution nx^2 +...

For example. L1: x = 11+3t y = 7+t z = 9+2t L2: x=-6+4t y=-2+3t z=-7+5t I was given this problem, and technically these lines don't intersect, right?

Hi, just got set a 3d Fourier transform to solve but I've never seen one before and can't find any examples online. once the integral is set up I should be fine but I'm not sure how to set it up; What is Fourier transfrom (f(k)) of following 3d function for k=(kx, ky, kz)=(1,2,3) for...

Dear frnds, suppose one have a 3D matrix, A=ones(3,3,3); he wants to have eigen value of A, then, A-Lamda*I=0 where A is 3D matrix, I is 3D matrix. now Problem is our mathematical soft can only do 2D inversion or eigen calculation. Please refer me any info to find out the...

This not so much of a homework proble, but something I need to visualize and understand to do a homework problem. If theeres and atom at x,y,z = 0, and one located at x,y,z, = 1/2 and we pull second atom from its posistion with a force F in anyone of the x,y,z directions, what are the...

Hi I have an issue I am trying to solve, so far I haven't managed to get past it. I have some data for 200 points in theta from 0 to 2PI. The data is spherically symmetric so there is no phi dependence. Basically what I want to do is turn the 2D plot into a 3D by revolving the 2D plot. My...

I need to take the 3-Dimensional Fourier transform of a point charge potential. I have an integral of this form, but I am unsure as to how to approach this integral. \int e^{-i\vec{x}\vec{k}} \frac{q}{|\vec{x}-\vec{x'}|}d^3x A push in the right direction would be appreciated.

Hi, Can anybody help me to find the polar angle and the azimuthal angle of a given 3D vector? Say we know the ordinates of the two point A(x1,y1,z1) and B(x2,y2,z2). So the question is find angles (Theta and Phi) of the vector AB. Any suggestion would be really appreciated. Thanks. Susantha

Just like we can draw 3D-looking images on paper, has anyone tried to "draw" out a 4D image onto 3D space? It's not really drawing, more like building. Since nobody can visualize 4D, it would have to be done mathematically. I've seen projections of hypercubes onto 3D, but it was still 2D since...

An explanation given to the question, "Why do I look different in pictures versus a mirror?", cited that in a picture one views a 2D image but in a mirror one views a 3D image. This difference can effect the depth perceived in ones face. Is this explanation valid? My take is that the...

Homework Statement In a solid state book I am reading the 3 dimensional electron gas is derived. It says, "An unconfined electron in free space is described by the Schrodinger equation where m is the free-electron mass. The solutions of the equation, phi(r)=1/(2pi)^3 Exp(ik.r) are plane...

For example, how would I plot the fixed vector <3, 4, 3>? I'm not sure if I'm using the correct language; I mean the vector with its tail at (0, 0, 0) and head at (3, 4, 3).Also, how would I plot the plane 11x + 19y + 39z = 88?

Hello everybody! I'm dealing with a MATLAB script that is made up in this way: I've this external loop % ALTITUDE [ft] h_ft = 0:200:10000; % TEMPERATURE [°C] T_C = 0:1:50; for mm = 1:length(h) for nn = 1:length(T_0) The aim of this loop is to calcuate a velocity, so at the end I...

Hi! My problem is connected with solving 3-dimentional Schrodinger equation for descrete spectrum. I need to consider arbitrary 3D-potential and find characteristics of boundary levels, produced by this potential (energy levels, quantum numbers...) All I found over the internet were...

I was wondering, after reading a few posts on various things related to 'The clockworks of the solar system' such as angular velocity and orbital periods,in a 3-dimensional sense, are planets orbital paths all over, or are they flat on one plane, varying in only 2 dimensions? i imagine it...

Who here has seen it? I saw it today in 3D imax. After my eyes stopped hurting I rather enjoyed myself. Not a bad way to get back into the series.

[PLAIN]http://img337.imageshack.us/img337/3623/pensp.jpg Homework Statement I need to find the equations of motions via Lagrange's formulation when the generalized coordinates are: \vec{q}=[x,y,z]^T2. The attempt at a solution I need to verify whether what I obtained so far is true or not...

Homework Statement A 1125 N force F is supported by cable AD and by struts AB and AC as shown. If the struts can transmit only axial tensile or compressive forces, determine the forces in the struts and the tension in the cable. a = 6 m b = 1 m c = 4 m d = 6 m f = 2 m...

Hi, I just saw this video on youtube, originally from Carl Sagan's 'Cosmos', about a 4th spatial dimension. http://www.youtube.com/watch?v=Y9KT4M7kiSw&NR=1" So what happens when the photons that are traveling in 3D hit an object in a 2D plane universe. To a 2D object it seems like photon...

http://arxiv.org/abs/1011.5049 The Quantum 3D Superparticle Luca Mezincescu, Paul K. Townsend (Submitted on 23 Nov 2010) The minimal (N=1) superparticle in three spacetime dimensions (3D) is quantized. For non-zero mass it describes a spin-1/4 semion supermultiplet of "relativistic...

I have a nifty expression \frac{1}{r} = \frac{\rm{erf}(r/\alpha)}{r} + \frac{\rm{erfc}(r/\alpha)}{r} I can manipulate it easily enough in one dimension to get a similar expression for \frac{1}{|r|}. Having a little trouble with the expression in three dimensions though\frac{1}{|\textbf{r}|}...

I often look up at the sky and wonder how far away this or that star/object is. I know that most discernible stars are in our neighborhood, but I have a hard time figuring out just how close they are. Is there a map/graphic that would map all the objects we can see with a naked eye in our...

Curious as to whether there's a formula for calculating the shape of the magnetic field lines, including electro magnets (solenoids). I want to create a 3D graphical display for the magnetic field lines of magnets.

Show that the kinectic energy of a three-dimensional fermi gas of N free electrons at absolute zero is (Mathematica code used) u = 3/5 N Subscript[\[Epsilon], F] Now I know total energy of N particles is this integral u = \!\( \*SubsuperscriptBox[\(\[Integral]\), \(0\)...

Hello All, I am looking for a way to find a point on a line (eg. line 1). This line has a perpendicular which has an intersection with another line in 3d space (line 2). I have the coordinates of line 1 and 2 and their direction vectors (lines have an infinite length). I also have the...

Hi, I'm pondering the relation for the surface integral of a membrane \sqrt{1+\nabla \psi \cdot \nabla \psi} My two questions are: 1) Does this expression have an identical form if the "membrane" is a scalar field in 3 dimensions (like Temperature) 2) How does one derive this result for 3...

I am trying to create a kind of rudimentary 3d positioning system, sort of like a CNC minus the machining aspect. I am just trying to get my very basic design down and I am stuck at how i should get the position data, my first thought was to use an accelerometer placed at the tip of the actuator...

Homework Statement Two lines are given p: \stackrel{\rightarrow}{r}(t) = (4,7,4) + t(2,2,-8) and q: z = 3, x = 7 -y (second one is given in parametric form). Questions: a) find a function f(x) which has a value in x that equals a distance from a point \stackrel{\rightarrow}{r}(x)...

How to calculate 3D Principal stresses? If I got the values of 6 stress tensors: Then I can calculate the values for the 3 stress invariants I1, I2 and I3: I also know the relationship between the stress invariants and principal stresses: So how can I calculate the values for the...

Hi all, Does anyone know how to get Mathematica make a 3D plot with logarithmic axes? I need a, say, 3D version of LogLogPlot. I have a 3D function Rdb[nf, pf] which I want to plot for {nf, 10^10,10^18} and {pf, 10^10,10^18}. I can get cross sections of what I need when I do...

Homework Statement Show that the shortest distance between two points in three dimensional space is a straight line. Homework Equations Principally, the Euler Lagrange equation. The Attempt at a Solution I understand how to do this for a plane, but when we move into three...

"simple" 3d orbit question Hi folks, I am following this pattern: http://www.bit-101.com/tutorials/3D-rotation.html to build a 3d model of an atom, using silverlight. I have what i think is an easy question for math pros... I'd like to know what I can change to make the angle of the...

Hello, As part of my final year project I am to run a CFD analysis of a pump impeller. I have been provided with the impeller and diffuser CAD models and successfully imported these into gambit. However, after completing a number of the gambit tutorials I still have no experience in meshing...

i have an object and a 3d direction vector and position for it . I would like to know how do i determine if a certain point X is in the space below the plan determined by my direction ? Here is an image that i have drawn to make it more clear . In this image I've made the vector 2d...

Hello everybody, I just have no idea how to start this problem so i was hoping you guys would point me in the right direction and then i'll be able to go on by myself the problem asks to show that the total ground state energy of N fermions in a three dimensional box is given by E total =...

Few days back I posted a question here that dealt with inversion geometry. A point P inside a sphere can be inverted with respect to the spherical surface to another point P' outside. Center of the sphere O,P and P' are collinear and OPxOP'=r^2 I was wondering if it is possible to get a 3D...

Hi there. Well, I got a surface plotted with Mathematica. I've used the Plot3D command for this. But now I want to plot a point in the same graph. The thing is I've used Taylors polynomial of second degree, and I want to "see" the point around which I'm making the approximation. But I don't know...