3d Definition and 1000 Threads

  1. A

    MATLAB Creating 3D Scatter Plot in Matlab - Ashley, IU Chemistry

    Hello I am very new to Matlab and need help on importing my data for a 3D plot. Currently, I have x,y,z data that I am trying to import to look like Figure 5 in the following paper: http://www.nature.com/nmeth/journal/v4/n5/fig_tab/nmeth1038_F5.html I have no idea how to import the...
  2. E

    Calculating an elliptical surface and formulating this surface in 3d

    Hello. Let's think that we have a sphere that shown in the picture above. The user will select 4 different point the Earth's surface. Then I must merge this points with shortest curves, then I got a surface. (Like picture 2) Because of the world's surface, our area is elliptical. How can I...
  3. E

    Calculating an elliptical surface and formulating this surface in 3d

    Hello. Let's think that we have a sphere that shown in the picture above. The user will select 4 different point the Earth's surface. Then I must merge this points with shortest curves, then I got a surface. (Like picture 2) Because of the world's surface, our area is elliptical. How can I...
  4. Vorde

    3D Model of the 2MASS Redshift Survey

    Does anyone know of a 3D model of the data from the 2MASS Survey? I have to imagine it would be incredibly easy to code, but I haven't found one. Thank you.
  5. Femme_physics

    3D statics - looks impossible to solve

    This question was on my mechanics test but I skipped it. It seemed kinda crazy. Homework Statement In the drawing is described a weightless beam AC connected to the wall through joint C. The beam is supported by two cables, BE and AD, connected to the wall. At the end of the beam at...
  6. L

    How Do You Fit 3D Coordinate Data to a Parabola?

    Homework Statement I'm trying to go about fitting some (x,y,z) coordinate data that I got out of a simulation to a parabola, but I'm not entirely sure how. Is there a general equation for a parabola that instead of having usual (x,y) coordinates has (x,y,z) coordinates? Homework Equations...
  7. E

    Help needed with 3d geometry problem: important

    help needed with 3d geometry problem: important! Homework Statement find the equations of the two planes through the origin which are parallel to the line (x - 1)/2 = (-y-3) = (-z-1)/2 and at a distance of 5/3 from it. also, show that the planes are perpendicular Homework Equations...
  8. A

    What is the cross product of two 3D vectors?

    Homework Statement Homework Equations A=i+j-2k C=j-5k The Attempt at a Solution How to obtain the correct answer?
  9. H

    Distance between point and 3D spline

    Hello, I have a few dozen nodes spaced in a helix shape and an object trying its best to follow the path of the nodes. The nodes are like pylons/cones on the road, and the object is the car trying to navigate and follow them. The helix isn't perfect, so I am thinking to use a spline curve to...
  10. A

    Nonlinear Orthonormal Bases for Dynamical Systems in 3D

    I propose 27 scalar functions {fn : n = 1,2,…,27}, 9 delay-coupled 3D unit vectors {eij : i,j = 1,2,3} of general periodic nature, 7 ortho-normal bases {Zk : k = 0,1,2,…,6} each having three 3D unit vectors, 4 tensors {Y3,Y4,Y5,Y6} of order 2 and a tensor E of order 3. Z3-Z6 and E are defined...
  11. N

    Solving a 3D Integral: Finding the Volume Enclosed by x=y, z=0, and y^2+z^2=x

    find the volume enclosed by x=y z=0 and y^2+z^2=x i built \int_{0}^{1}\int_{x}^{\sqrt{x}}\int_{0}^{\sqrt{x-y^{2}}}dzdydx i tried to traw the projection of the top interval in the z-y plane z=\sqrt{x-y^{2}} -> z^2+y^2=x so we have a circle but the radius changes from x to...
  12. rhody

    Medical But I digress...Explore the Intricacies of Swine Anatomy with Visible Body 3D!

    FYI. I ran across http://www.visiblebody.com/", and thought I would share... It is pretty cool... Rhody... :approve:
  13. I

    Can Smooth Curves in 3D Have Cusps?

    "smooth" curves with cusps in 3d While reviewing basic calculus, I noticed that the curve (1+t^2,t^2,t^3), which clearly has a cusp at (1,0,0), has a derivative curve (2t,2t,3t^2) which is clearly smooth. This struck me as odd since differentiation usually seems to turn cusps into...
  14. G

    How do I create a tornado figure using plot3 and comet3 commands?

    Homework Statement Hi, I'm taking Intro to Computing for Engr. and my highest level math course I have taken is Calculus I. I'm trying to solve this problem in my book for Intro to Computing for Engr. and believe that the math is over my head. This may well be the case. But sense this...
  15. C

    3D Schrödinger Equation for a magnetic vector potential in cylinder coordinates

    Hi there, during my work on my PhD thesis as an experimental physicist I ended up with a very theoretical problem: What does the wavefunction of an electron traveling through a magnetic vector potential look like? I chose a cylindrical coordinate system with a magnetic vector potential A...
  16. H

    Are 8D Movies More Immersive Than 3D Films?

    How often do you watch 8D movies ? or do you watch mostly 3D. How many theatres are there in your locality? My other question is Do 8D theatres need more preparation time to load the movies ( i guess lot of weeks) than 3D(which is instantaneous)? I think 8D theatres need to prepare for...
  17. Femme_physics

    3D statics - is there a simpler, shorter way to solve problems?

    Do I have to do three 2D free-body-diagrams like I did here -> https://www.physicsforums.com/showthread.php?t=503368 Or is there a shortcut?
  18. H

    3D magnetic field simulation software (open source)

    Hi Everyone, Can anyone tell me an "open source 3D MAGNETIC FIELD SIMULATION SOFTWARE", which can add more than 3 magnetic fields and then give their resultant magnetic field... Any help will be appreciable. Regards, hsn
  19. J

    Centroid of a 3D Region using Triple Integral

    Homework Statement Compute the centroid of the region defined by x^{2} + y^{2} + z^{2} \leq k^{2} and x \geq 0 with \delta(x,y,z) = 1. Homework Equations \overline{x}=\frac{1}{m}\int\int\int x \delta(x,y,z) dV \overline{y}=\frac{1}{m}\int\int\int y \delta(x,y,z) dV...
  20. Femme_physics

    Solving the Mystery of 3D Mechanics: Is the Sum of Moments 0?

    I recently fall upon this principle while trying to do this 3D mechanics exercise. http://img193.imageshack.us/img193/1416/legitwheel.jpg Looking from a side view (only z and y axes), this should be about right: http://img28.imageshack.us/img28/5758/momentsq.jpg Ignore the question marks...
  21. Femme_physics

    Solving 3D Statics Problem: Calculating Tension and Reactions

    I've kicked it up a notch and tried tackling 3D statics :approve: Homework Statement http://img849.imageshack.us/img849/4640/attempt01drawing.jpg A rectangular board is held in the condition shown in the drawing by clutching devices A and B (I couldn't find the exact translation in Hebrew...
  22. T

    Pitch for a 3d hyperbolic spiral

    Hi, have worked out the formula for a hyperbolic spiral space curve to be r(t)=1/t X cos(alpha)+1/t X sine(alpha) + t and obtained the tangent vector T, normal vector N, and curvature (kappa) with the z axis being the central axis of the spiral. Am having trouble finding the formula for the...
  23. W

    Variational Calculus to minimize distance on a generalize 3D surface

    Homework Statement A mountain is modeled by z=f(x,y) which is a known function. a) What are the differential equations for x(t) and y(t) that minimize the distance between 2 points. b) If z=f(x,y)=(\sin^2 2\pi x)(\sin^2 2\pi y) Solve the equations. Homework Equations The...
  24. L

    3D glasses and polarization, how it works?

    I was thinking about how does the 3D glasses(not the one with red and blue lens) work. My first idea is that the lenses are polaroids with orthogonal polarization. So I got a 3D glasses from a cinema and try to prove it. I wear the glasses properly(with the arms on my ears) and then look at...
  25. P

    Do these 3D vectors intersect at the given points?

    If I put these 2 lines into wolframalpha.com it comes up with a solution x = 1 + 2t , y = 2 – t , z = t ; x = -2 – s , y = 3 + 3s , z = 1 + 4s t = -8/5 and s = 1/5 using equations for x & y Solution; x = -11/5 y = 18/5 z = 9/5But the z values do not match so how can these...
  26. D

    Converting 2D Movies to 3D: How is It Done?

    How do they convert movies that were shot in 2D to 3D? I recently saw that they were rereleasing Titanic in 3D... Doesn't this require multiple camera angles? or is it more like doing a 'cutout' of the actors and placing them on a Z-Plane? The other method I can think of is recreating the sets...
  27. S

    What is the Correct Approach to Solving This 3D Fourier Transform Problem?

    Homework Statement What is the function f(r) s.t int {d3r.f(r).e-iw.r= 1/w2} where w = (kx,ky,kz) Homework Equations None The Attempt at a Solution I tried to directly take Fourier transform of 1/w2 as \int{ d3r.1/w2.eiw.r}. I started integrating dkx bu calculus of residues, calling the...
  28. T

    Creating a Vector Field from a 3D Parametric Equation

    I am trying to turn a 3D parametric equation into a vector field for an experiment, but I am not having much luck. [x,y,z]=[r*cos(u),r*sin(u),a*u] is the equation, I'm using grapher on the Mac. I want it all going in a helix, which is what the equation is for. Thanks!
  29. ChristinaJ

    Mathematica Mathematica: Plot time evolution data in 3D

    Hi all, I have 3 lists of data where lists; A={numbers}, B={numbers} and C={{y,m,d,h,m,s},{...}} (i.e. C is in the form DateList). I have no problem plotting using DateListPlot for the 2D case (C VS A) but can't seem to plot all 3 sets of data together. Mathematica seems not to be able...
  30. S

    Calculating Fixed End Moments with Uneven Beam Heights?

    Ok, so I have a problem as follows: A beam is simply supported at joints A, B, C D and E. there is a UDL acting on the BC member The member is 6m long with a UDL of 60kn/m However the tricky part is that this member is 1.2 times higher than the height of the members AB, CD, and DE. So BC =...
  31. P

    The 3D modeler, newbie and odd questions box

    Hi I do 3D modeling and lately i have been trying to make some more theoretic diagrams about the whole thing. Sometimes i try to go through ways where math and geometry are needed (or so i think) and my background is not up to it. I'll use this thread to post some initial questions per post...
  32. M

    Mathematica Plot 3D matrix as 2D plot and 3rd dimension as color in Mathematica

    Hi! It's been like two days since I have tried to make this work, still I got nothing. Searched Google etc. but no help there. I have a three dimensional matrix in form of {{a,b,c}, {d,e,f}, {g,h,i}, ... etc. } with a total of 51 elements, i.e. 51x3 matrix. What I want is to plot it as...
  33. M

    Proving three 3D points are collinear with Cross Product

    Hi. I've been studying for a test and have been scouring my text for methods of proving points in 3-dimensional space are collinear. The best I can see is that the cross-product of the vectors must equal zero. Can someone explain how to do this a little more clearly?
  34. Femme_physics

    Is the transfer from 2D mechanics to 3D mechanics intimidating?

    How much more than is to learn when you go from 2D to 3D? I'm curious to know whether all these problems I solve in 2D are less helpful for when we move to 3D, where there are more elements?
  35. atyy

    Turaev-Viro, Levin-Wen, 3D gravity

    What is the relationship between these? On the TV and LW side, these seem relevant http://golem.ph.utexas.edu/category/2011/03/liang_kong_on_levinwen_models.html http://arxiv.org/abs/1004.1533 http://arxiv.org/abs/1004.1737v2 On the TV and 3D gravity side, this seems relevant...
  36. atyy

    Is 3D Quantum Gravity Equivalent to a TQFT?

    I'd always assumed it was, since LQG spin foam models are based on BF theory. And it is typically said that in 3D it is BF, and in 4D constrained BF. The 4D quantum case is not known to be gravity, but I had thought the 3D case was. Yet in http://math.ucr.edu/home/baez/week254.html Baez...
  37. K

    Understanding 2D and 3D Stress: Differences and Applications Explained"

    Dear all, I having a trouble in defining 2D and 3D stress . As I know Maximum principal stress in 2D and 3D cases is totally different. In which condition we should apply 2D stress formula and when we need to use 3D stress formula?
  38. D

    Finding default unit vectors in 3D modelling

    When you are modelling elements like tubes, the local x-axis is defined along the tubes length. If a unit vector for the z-axis is not applied, modelling softwares defaults to a coordinate system where the local zx-plane is parallel with the global zx-plane. I'm not sure what that means...
  39. S

    Can CAD be replaced by 3D software?

    I have seen a lot of 3D software users of Modo, 3ds Max, Maya, etc that can produce a very nice looking product designs. These ranges of items made by them include car, building, machine, airplane, household electrical product, etc. They all look as good as the outcome produced by the CAD...
  40. T

    Addition of 3d force vectors to find resultant

    Homework Statement A force of 5N acts along the vector (-4,-3,-1) A force of 2N acts along the vector (-3,-6,5) A force of 4N acts along the vector (-9,-1,8) find the resultant force vector. Homework Equations The Attempt at a Solution i tried to multiply the vectors by the...
  41. J

    Confused- Integrating a vector field along a curve in 3D.

    Homework Statement Let f be a vector function, f = (xz, 0, 0), and C a contour formed by the boundary of the surface S S : x^2 + y^2 + z^2 = R^2 , x ≥ 0, y ≥ 0, z ≥ 0 , and oriented counterclockwise (as seen from the origin). Evaluate the integral (Closed integral sign) f · dr , directly as...
  42. E

    Deriving Energy and Wave Functions from 3D Schrödinger

    Homework Statement I have a quantum harmonic oscillator with quantum numbers nx,ny,nz ≥ 0 and frequency ω0. There are three parts to the problem. To me it seems they are out of order, but I'm kind of shaky deriving these. a) Write down the energy level Enx,ny,nz of a QHO in 3d with quantum...
  43. Darken-Sol

    If a 3D object has 4 points. why use x,y,z to describe 3D?

    if the first 3D object has 4 points. why use x,y,z to describe 3D? am i confused about one or more concepts? does a tetrahedron skip 3D? a plane plus another point some where off that plane would immediately provide 4 directions to move. one for each point. could these directions not be used to...
  44. E

    Probabilities Inside Cubic 3D Infinite Well

    Homework Statement An electron is trapped in a cubic 3D infinite well. In the states (nx,ny,nz) = (a)(2,1,1), (b)(1,2,1) (c)(1,1,2), what is the probability of finding the electron in the region (0 ≤ x ≤ L, 1/3L ≤ y ≤ 2/3L, 0 ≤ z ≤ L)? Homework Equations My normalized wave function in the...
  45. R

    Calculating the Commutator of H and r in 3D - What is the Correct Solution?

    Homework Statement [\hat{H},\vec{r}]= ? The Attempt at a Solution The answer is given, and I KNOW that factor of 6 shouldn't be there. The answer should be -\frac{\hbar^2}{m} \nabla Anyway I've always been lurking these forums and I enjoy the discussions here, but this factor is...
  46. C

    Relationship between PWM, Torque and Duty for a 3D Crane System

    I am working on a 3D crane system, the system has three dc motors for y, x and z axis, and i control them with a PWM signal. i need to find the relationship between pwm and torque or torque and duty. could someone help me, thanks
  47. M

    New 3D model of solar system and night sky

    Hi, for all of you we´ve made new user-friendly interactive 3D model of solar system and night sky with real-time planet´s positions. http://www.solarsystemscope.com/ (requires flash) Application in a simple way helps students and laymen to understand the movements of the planets and...
  48. N

    MATLAB Plotting XYZ Coordinates in 3D with Matlab

    Hi all This is my first time here, so I will do my best to explain what I need help with. I have 2 sets of 11 xyz coordinates of some beads that I would like to plot in 3D. I want to show them in 3 space as a before and after (to represent a displacement of each point). I was able to...
  49. A

    Volume of Revolution: Cylinders vs Washers

    Homework Statement Find the volume of the solid bounded by the curves y = x^{1/3} and y = x when rotated around y=1. Homework Equations Volume with washers: V = \pi \int R(x)^{2}-r(x)^{2} dx where R(x) and r(x) are functions of x defining the inner and outer radii of the washers...
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