Re: Mesh, membrane, oscillations

[Rob Mahurin]

On May 24, 2009, at 4:19 AM, Adrian Spiridon wrote:
> Hello there,
>
>         I need to simulate a square membrane oscillation (like  
> http://www.kettering.edu/~drussell/Demos/MembraneSquare/ 
> Square.html), but ussing Bessel's
> function of the first kind (besselj). The task is to use as  
> starting point a vector y=besselj(0,v1:0.1:v2) , where v1 and v2  
> are the zeros of the derivative of the bessel's and of the bessel's  
> function (eg.: first zero of the derivative and the second zero of  
> the function, then third zero of the derivative and the fourth zero  
> of the function, and so one, depending on how many oscilations we  
> want). The reason of choosing this ends of the interval is that we  
> want to have maximum in the center and zero on the margin of the  
> figure.
>         For example, for the first oscillation, y would be y=besselj 
> (0,0:0.1:5.52) , where  0 is the first root of the derivative and  
> 5.52 tthe second root of the function. From this results the first  
> figure in the drum file attached.(the second 2 figures are the next  
> 2 oscillations).
>         After plotting the vector y, I obtained like a "thread"  
> from the surface(see plot and mesh files for different views of the  
> graphic).
>         The question , for this particular case (this y - first  
> oscillation), is how to generate  the entire membrane like in  
> figure 1 ? My first ideea was to rotate the graphic of y, but the  
> teachers said that this is not a circular membrane oscillation so  
> this method isn't good. They suggested creating a matrix from the  
> vector y using the exterior product, and then just use mesh 
> (matrix). But how on earth can I do this ?My problem is that the  
> membrane has no radial simetry as you can see from he images.


I'm not quite sure I follow you, but look at "meshgrid."

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Cheers,
Rob

--
Rob Mahurin
Department of Physics and Astronomy
University of Tennessee                 865 207 2594
Knoxville, TN 37996                     address@hidden