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From: "hyun doo ahn" <hjlovme@hotmail.com>
Newsgroups: comp.soft-sys.matlab
Subject: Re: circular plate 3D plot
Date: Mon, 3 May 2010 18:52:26 +0000 (UTC)
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"Roger Stafford" <ellieandrogerxyzzy@mindspring.com.invalid> wrote in message <hrn0fc$s6m$1@fred.mathworks.com>...
> "hyun doo ahn" <hjlovme@hotmail.com> wrote in message <hrmr2n$sij$1@fred.mathworks.com>...
> > Dear all
> > I know how to make 2d circle plot by polar function
> > I have a question to make a circular plate 3D without polar3d
> > .......
> 
>   As you have stated the problem you have a circular ring, not a "plate", in the x-y plane.  To make this a solid disk which would be appropriate for using 'surf' you need to have a mesh containing both a varying theta and a varying radius.  Perhaps you mean to do something like the following.
> 
>  radius = linspace(0,20,10); % For ten rings
>  theta = (pi/180)*[0:45:360]; % For eight angles
>  [R,T] = meshgrid(radius,theta); % Make radius/theta grid
>  X = R.*cos(T); % Convert grid to cartesian coordintes
>  Y = R.*sin(T);
>  Z = (corresponding values of Z in terms of X and Y)
>  surf(X,Y,Z) %Plot the sound pressure surface
> 
>   If you really do have only a ring, then you should be using 'plot3', not 'surf'.
> 
> Roger Stafford


thank you very much Roger^^

I got the idea from you.

I clealy undertood how to work