# mesh plot

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## mesh plot

 I am trying to get a mesh plot in a program where I think the N and iter values are very high.  So it is taking too long. Is there some way I can change the following code in order to just get a sample of 1 in 5 or 1 in 10 points. That might reduce the density and may speed the whole thing. Please advise. Thanks Asha G  colormap(gray)view(30,45)[xx,zz]= meshgrid(x,z);mesh(xx,zz,y)qm = [xx(:) zz(:) y(:)];save -mat-binary cabunbact1doctN41mesh xx zz ysave -ascii cabunbact1doctN41meshascii qm       _______________________________________________ Help-octave mailing list [hidden email] https://mailman.cae.wisc.edu/listinfo/help-octave
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## Re: mesh plot

 On Fri, 2013-05-03 at 12:46 +0800, asha g wrote: > I am trying to get a mesh plot in a program where I think the N and > iter values are very high. Your script doesn't refer to either 'N' or 'iter', so the following is a *guess* that 'N' is numel(x) and 'iter' is numel(z).  Furthermore I *assume* that the quantities 'x', 'y', and 'z' are computed by some external means, have conformable dimensions and Just Exist[tm] in your environment. To pick up every five elements of 'y' in each coordinate direction, you could do something like this:         i = 1 : 5 : numel(x);         j = 1 : 5 : numel(z);         mesh(z(j), x(i), y(i,j)) Adjust the stride (in this case, '5') appropriately if you want more or fewer points in your mesh plot. Note: mesh(z(j), x(i), y(i,j)) is not a misprint.  If you use vectors as coordinates, then number of rows of the third parameter must match the number of elements of the *second* parameter and the number of columns of the third parameter must match the number of elements of the first parameter. Sincerely, -- Bård Skaflestad <[hidden email]> _______________________________________________ Help-octave mailing list [hidden email] https://mailman.cae.wisc.edu/listinfo/help-octave
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## Re: mesh plot

 Your script doesn't refer to either 'N' or 'iter', so the following is a*guess* that 'N' is numel(x) and 'iter' is numel(z).  Furthermore I*assume* that the quantities 'x', 'y', and 'z' are computed by someexternal means, have conformable dimensions and Just Exist[tm] in yourenvironment.To pick up every five elements of 'y' in each coordinate direction, youcould do something like this:        i = 1 : 5 : numel(x);        j = 1 : 5 : numel(z);        mesh(z(j), x(i), y(i,j))Adjust the stride (in this case, '5') appropriately if you want more orfewer points in your mesh plot.Note: mesh(z(j), x(i), y(i,j)) is not a misprint.  If you use vectors ascoordinates, then number of rows of the third parameter must match thenumber of elements of the *second* parameter and the number of columnsof the third parameter must match the number of elements of the firstparameter.Am running it right now. Will keep you posted on whether I get the required result.Asha  _______________________________________________ Help-octave mailing list [hidden email] https://mailman.cae.wisc.edu/listinfo/help-octave
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## Re: mesh plot

 In reply to this post by Bård Skaflestad          i = 1 : 5 : numel(x);        j = 1 : 5 : numel(z);        mesh(z(j), x(i), y(i,j))Adjust the stride (in this case, '5') appropriately if you want more orfewer points in your mesh plot.Note: mesh(z(j), x(i), y(i,j)) is not a misprint.  If you use vectors ascoordinates, then number of rows of the third parameter must match thenumber of elements of the *second* parameter and the number of columnsof the third parameter must match the number of elements of the firstparameter.N = 41, iter = 111000;vvvv(iter,:) = V;tmax = 55; x= linspace(0,tmax,niter);z = linspace(0,l,N);y = vvvv';On using the following i = 1 : 5 : numel(x);        j = 1 : 5 : numel(z);        mesh(z(j), x(i), y(i,j))I get an error message at line mesh(z(j),x(i),y(i,j))error: A(I): Index exceeds matrix dimension.Maybe it needs to be rewritten Asha G  _______________________________________________ Help-octave mailing list [hidden email] https://mailman.cae.wisc.edu/listinfo/help-octave
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## Re: mesh plot

 On Fri, 2013-05-03 at 17:46 +0800, asha g wrote: > N = 41, iter = 111000; > vvvv(iter,:) = V; Okay.  This means that 'vvvv' has (at least) 'iter' (=111,000) rows. You haven't said how many columns it has though.  I'm forced to assume that it has N columns and that 'V' (whatever that is) is a 1-by-N (i.e., a 1-by-41) row vector. > > tmax = 55; > x= linspace(0,tmax,niter); I'm confused.  What is 'niter'?  Is it the maximum value of 'iter' or something else entirely?  Whatever it is (presumably a positive integer), at least we know that         all(size(x) == [ 1, niter ]) > z = linspace(0,l,N);         all(size(z) == [ 1, N ]) > y = vvvv'; Size unknown.  In the following, I'm going to assume that         all(size(y) == [ N, niter ]) because that seems the most likely given your setup.  If that is not the case, then you *really* need to tell us the size of 'y'. > On using the following >    i = 1 : 5 : numel(x); >    j = 1 : 5 : numel(z); >    mesh(z(j), x(i), y(i,j)) > I get an error message at line mesh(z(j),x(i),y(i,j)) > error: A(I): Index exceeds matrix dimension. That's seems consistent with the fact that numel(x) (i.e., 'niter') is (much) larger than numel(z) (i.e., 'N'). > Maybe it needs to be rewritten By 'it' I assume you mean the 'mesh' call, rather than your own calculations.  I already said in a previous e-mail that in an invocation like         mesh(U, V, W) in which 'U' and 'V' are vectors, then the following conditions must hold         rows(W)    == numel(V)         columns(W) == numel(U) In other words, your 'mesh' invocation must then (assuming, as stated above, that all(size(y) == [ N, niter ])) be written as         mesh(z(j), x(i), y(j,i)) Sincerely, -- Bård Skaflestad <[hidden email]> _______________________________________________ Help-octave mailing list [hidden email] https://mailman.cae.wisc.edu/listinfo/help-octave
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## Re: mesh plot

 On Fri, 2013-05-03 at 13:39 +0200, Bård Skaflestad wrote: >         mesh(z(j), x(i), y(j,i)) Sorry.  That should be         mesh(x(i), z(j), y(j,i)) Sincerely, -- Bård Skaflestad <[hidden email]> _______________________________________________ Help-octave mailing list [hidden email] https://mailman.cae.wisc.edu/listinfo/help-octave
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## Re: mesh plot

 In reply to this post by asha g On 05/03/2013 10:46 AM, asha g wrote: > > Maybe it needs to be rewritten > > Asha G Off-topic: could you please refrain from sending HTML emails? -- Zé _______________________________________________ Help-octave mailing list [hidden email] https://mailman.cae.wisc.edu/listinfo/help-octave