Hiya, For my phd thesis, I wrote a custom unstructured finite element (tri / tet) 2D/3D reaction-diffusion solver in matlab. It uses an adams- bashforth / trapezoidal predictor-corrector time integrator with a customised GMRES linear solver (which itself uses matlab's '\' operator), with adaptive time-stepping based on the Gresho and Sani depiction in their CFD books. Hence, this thing handles multiple space and time scales - which I needed for the computational cell biology modeling I performed. Note, there's no Newton solver in it...yet? Anyway, I'm curio...

I'm trying to solve numerically a 2d/3d reaction-diffusion equation using NDSolve. The system can be solved for one spatial dimension (+ time dimension), but it does not converge for two spatial dimensions (x,y,t). Actually, I'm trying to use polar coordinates (r, phi, t), because the problem has a point source. I'm using NDsolve with the following method: Method -> {"MethodOfLines", "SpatialDiscretization" -> {"TensorProductGrid", "Coordinates" -> myGrid} which fails. Can you recommend a better method to solve the problem in 2D (and eventually in 3D) ? Kind regards, Alois On Tue, 4 Jan 2011, Alois wrote: > I'm trying to solve numerically a 2d/3d reaction-diffusion equation > using NDSolve. The system can be solved for one spatial dimension (+ > time dimension), but it does not converge for two spatial dimensions > (x,y,t). Actually, I'm trying to use polar coordinates (r, phi, t), > because the problem has a point source. > > I'm using NDsolve with the following method: > Method -> {"MethodOfLines", "SpatialDiscretization" -> > {"TensorProductGrid", "Coordinates" -> myGrid} > > which fails. Can you recommend a better method to solve the problem in > 2D (and eventually in 3D) ? > > Kind regards, > Alois > > > > Alois, you find an example of one...

How would you write a MATLAB code for the explicit finite differece eqaution? The diffusion equation (in 1-D) is dependent on a spatial variable (x) and a time variable (t). How would you write this in a loop in matlab? I get an error message for defining the equation C(x)=w*C(x+1)+(1-2*w)*C(x)+w*C(x-1) Katie Hoff wrote: > How would you write a MATLAB code for the explicit finite differece eqaution? > The diffusion equation (in 1-D) is dependent on a spatial variable (x) and a > time variable (t). How would you write this in a loop in matlab? I get an > error message for ...

i want to write Matlab program of gaussian beam (2D or 3D) using helmholtz equation.... if anyone could give the full program, that will help me to do my project work...... thank you :) "Debashis Roy" <deba4u@ymail.com> wrote in message <lhv04i$6sf$1@newscl01ah.mathworks.com>... > i want to write Matlab program of gaussian beam (2D or 3D) using helmholtz equation.... if anyone could give the full program, that will help me to do my project work...... > > thank you :) If anyone could give the full program, they WILL do your project work, not just h...

i want Matlab program of gaussian beam (2D or 3D) using helmholtz equation.. help "Debashis Roy" <deba4u@ymail.com> wrote in message <lhv0dn$7ja$1@newscl01ah.mathworks.com>... > i want Matlab program of gaussian beam (2D or 3D) using helmholtz equation.. help Look at this link: <<http://en.wikipedia.org/wiki/Helmholtz_equation>> It might help. ...

Hi all, I am attempting to solve the diffusion equation for the concentration of a compound (MgO), where the diffusivity depends on the concentration of some other compound (SiO2). The concentration of SiO2 is itself determined by a differential equation. I have "solved" the problem, but the solution takes several hours when I think it ought to be much faster. Being quite sure that my solution is just an ugly hack, I'm hoping somebody has some advice on how to speed it up. The algorithm is as follows: Step 1: Solve the 1-D diffusion equation for SiO2 concentr...

Hi I want to know how I can plot some equation like this equation like this: x^3+ zyx^2+z^2yx+y^2xz+xyz+y^3+z^3=0 By and large how I can plot equation without parametrization in matlab. Thanks. "F.Vesali" <farshad.vesaly@gmail.com> wrote in message <ad978129-7f90-4685-b8d9-dc536dc63a31@r24g2000yqd.googlegroups.com>... > Hi > I want to know how I can plot some equation like this equation like > this: > x^3+ zyx^2+z^2yx+y^2xz+xyz+y^3+z^3=0 > By and large how I can plot equation without parametrization in > matlab. > Thanks. a hint: help ezplot; ...

Hello: I would like to generate a 3D graph in SAS. The points are (x,y,z). I would like to have a SCATTER plot on the (x,y) axes. But then each one of these (x,y) points are LINE connected to their respective z point. If anyone has code for this, or know how to do this in SAS, it would be so helpful. Thx!! I tried to attach the graph as a visual as part of my question, but apparently we cannot send .gif. ...

Hi, I was googling for a while, but I could not find anything. I would like to export the 3D meshes created in Matlab to Blender or different 3D rendering software like i.e. 3D Studio MAX. Does anyone have experience with that and some scripts or converters that wuold sovle tihs problem ? Thanks Kamil Kamil G. wrote: > Hi, > > I was googling for a while, but I could not find anything. I would like > to export the 3D meshes created in Matlab to Blender or different 3D > rendering software like i.e. 3D Studio MAX. > > Does anyone have experience with that and some scr...

Hi, everyone: I am studyiing the caculus of variation and the heat equation. But I do not quite understand the meaning of the steady-state equation. For the linear diffusion equation: u_t = c*△u its steady-state equation is 0 = c*△u Does this funcion mean that the diffusion process has reached a balance state, in which the net diffusion is zero (or the diffusion is stopped)? And what's the mathematical meaning of the stead state equation? Does this mean the solution of the heat equation? By the way, I found that the Euler-lagrange equatio...

Hi All, I am trying to plot a 3D grid onto a 3D image in Matlab. May I ask how to do it please? For example, I have got a 3D image with 201x201x201 voxels. I want to plot a 3D grid with 10 voxels spacing on to the image (there will be 21x21x21 cubes to form this 3D grid). I have got the coordinates of the grid in three matrix X, Y, and Z all sized 21x21x21. Then I want to plot both the image and the 3D grid using a Matlab function slidingviewer(...); at FEX. Here is an illustration of the image I want to get. NB: the grid has no need to be regular. http://i54.tinypic...

Hi I am having difficulties matlab programming the 2D wave equation( Helmholtz equation) expressed in terms of greens function (the boundary element integral formulation). Anyone who can give me feedback will be of great help as it is my thesis project. Vasishta, Normally I would not respond to the write my thesis posts - but I am doing something similar - and found the Student Version lacking - you need to buy the Partial Differential Equation toolbox. http://www.mathworks.com/products/pde/ ...

Hi to all, i would like to know if i can create a 3d model of the face of a person without using a 3D scanner. Could i use a normal digital photo camera??? Thanks Yeap you sure can, Its called structure from motion, you need to take several images from different angles, calculate the F matrix for the camera parameters of each camera, detect features common in all images (try harris corners) reproject the features from the images or view frame into some common view frame, triangulate the features (aka vertexes), taking into account reprojection errors etc and your done. Arash Partow ________________________________________________________ Be one who knows what they don't know, Instead of being one who knows not what they don't know, Thinking they know everything about all things. http://www.partow.net kingpin@freemail.it wrote: > Hi to all, > > i would like to know if i can create a 3d model of the face of a person > without using a 3D > scanner. Could i use a normal digital photo camera??? > Thanks ...

Hello: I am working w. PROC G3D per Art's nice recommendation below. When I try to pre-specify the order and spacing of the axes, SAS ignores it and just picks its own axis values. Also one of my axis is date, and I would like to make the font smaller or change it to numeric (MM/YY) so that they are legible. But I can't seem to get that to work either. My code dm 'log;clear;output;clear;'; options ps=*50* ls=*70* pageno=*1*; goptions reset=global border ftext=swiss gunit=cm htext=*0.4* htitle=*0.5*; goptions display noprompt; axis1 order=-*.15* to *.15* by *.05* ; ax...

OR Stats sent me a copy of the desired graph offline. While it looks very similar to the one shown in the example I originally provided, one of the graphs on the following link is even closer, and doesn't require activeX: http://statistics.unl.edu/faculty/bilder/stat873/data_sets.htm http://statistics.unl.edu/faculty/bilder/stat873/SAS.htm cereal_ch3.sas It uses the cereal data set which is also downloadable from the page. I'm posting it to the list as it was one more nice set of examples, including all data, which others might find useful. Art --------- On Sun, 20 Sep 2009 06:54:...

i have x,y and z all are column vectors of equal size.i want an equation such that z=f(x,y).please help "Karthi " <gdkkannan@yahoo.co.in> wrote in message <hv2g0o$5te$1@fred.mathworks.com>... > i have x,y and z all are column vectors of equal size.i want an equation such that > z=f(x,y).please help one of the very many solutions - given the abundantly exhaustive information you share with CSSM... z=x+y; us Karthi wrote: > i have x,y and z all are column vectors of equal size.i want an equation > such that z=f(x,y).please help Step 1: Pick the...

Hello, Can anybody help me to solve the following diffusion equation using Matlab? dN/dt = delta^2*N - alpha*N - lambda*alpha^2 delta = 0.00035, alpha = 1, lambda = 10 many thanks if you can help me out. Hi Ryan, The equation as written can be solved analytically. N = exp(b*(t-c)+d)/b where b = delta^2-alpha, d = lambda*alpha^2 and c is the constant of integration, determined by specifying some initial condition. To generate a solution in Matlab try one of the ode routines i.e. ode45 Hth Darren "Darren Rowland" <darrenjremovethisrowland@hotmail.com&...

Dear all I am wondering whether you could tell me how cut the equation in several pieces so that matlab can still recongises it as one equation. For example, I have a very long matlab equation like this: value_1=c.^(gamma_v+1/2)*exp(sgn(a)*c)*(1+u).^(gamma_v)./ (sqrt(2*pi)*gamma(gamma_v)*gamma_v)*besselk(gamma_v +1/2,c)*F_1_1(gamma_v,1-gamma_v,1+gamma_v,(1+u)/2,-sgn(a)*c*(1+u)); it is very long equation, I have typed it in one line. Can I make it two lines without introducing a new variable, like value_1? Cheers Ron "ronarld.chan@googlemail.com" <ronarld.chan@googlemail.com&g...

I'm doing a fourth year project...Im just starting out and was wondering if anyone would have any suggestions on where to start for this topic.... Melissa wrote: > > > I'm doing a fourth year project...Im just starting out and was > wondering if anyone would have any suggestions on where to start > for > this topic.... Hi GP Agrawal 's book on NL fiber is good start.. Dr. Abhay Kumar > > 4 years? I had to solve this problem in 6 months.... (NLSE + a constitutive equation which correlates the optical field to another physical quantity present i...

Hi, can I export equations from mathtype, mathcad, Ms word or from other program, as matlab plot title or axis? Thanks ...

How to change the shape of the bar plots in Matlab from squared to round bars? Is it even possible? ...

Hi All, I'm trying to solve the equation I=Iph-Io*(exp(V-I*Rs)/(n*Vth)-1)-(V-I*Rs)/Rsh in Matlab. I'd be glad if anyone will help me with this. Thanks. Don Optoelectronics homework? Use the <A HREF="http://en.wikipedia.org/wiki/Newtons_method"> ewton-Rapshon method</A>. Don wrote: > > > Hi All, > > I'm trying to solve the equation > > I=Iph-Io*(exp(V-I*Rs)/(n*Vth)-1)-(V-I*Rs)/Rsh in Matlab. > > I'd be glad if anyone will help me with this. > > Thanks. > > Don Greg, Thanks I know that method, however, I'm...

Hi, I wanted to know if there were any inbuilt commands in matlab to solve the equation of the form f(x)=0 numerically. The function f(x) is composed of user written functions. I would really appreciate any help of this as I need it for some urgent work. Thanks. In article <ef26062.-1@webx.raydaftYaTP>, "Apoorva Shende" <apoorvashende@indiatimes.com> wrote: > Hi, I wanted to know if there were any inbuilt commands in matlab to > solve the equation of the form f(x)=0 numerically. The function f(x) > is composed of user written functions. I would really apprecia...

Hello everybody.. I'm a new programmer in MATLAB. I need to know if there is any possibility to control/move a 3D character using MATLAB??? Do I need to learn another programming language with it; in order to reach my point?? If so, what should I do?? what books do I need to read??? For example, if I want to move my 3D character from one point to another point in (x,y,z) position, using commands. How can I do that?? I want to do that using a programming language and not by a character animation. Please help me with such a topic, Best regards. "shaima' &q...

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