MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi

Learn moreOpportunities for recent engineering grads.

Apply TodayTo resolve issues starting MATLAB on Mac OS X 10.10 (Yosemite) visit: http://www.mathworks.com/matlabcentral/answers/159016

Asked by Walter Manns on 7 Oct 2011

Sorry for the horrible english, but i don't know how to explain it otherwise.

I want to plot these matrices:

val(:,:,1) =

18 18 18 18 18 18 18 18 18 18 18 18 18 18 18 18 18 18 18 18 18 18 18 18 18

val(:,:,2) =

18 18 18 18 120 18 18 18 18 120 18 18 18 18 120 18 18 18 18 120 120 120 120 120 120

val(:,:,3) =

18.0000 18.0000 18.0000 18.9139 120.0000 18.0000 18.0000 18.0000 18.9139 120.0000 18.0000 18.0000 18.0000 18.9139 120.0000 19.0662 19.0662 19.0662 19.9802 120.0000 120.0000 120.0000 120.0000 120.0000 120.0000

val(:,:,4) =

18.0000 18.0000 18.0082 19.8115 120.0000 18.0000 18.0000 18.0082 19.8115 120.0000 18.0119 18.0119 18.0201 19.8234 120.0000 20.1118 20.1118 20.1200 21.9041 120.0000 120.0000 120.0000 120.0000 120.0000 120.0000

On the same graph, so i can see (with colors) how the matrices develop trough time. The matrix itself shows me the spacial location. The numbers on the matrix shows the temperature, and the first matrix is time = 1, the next time = 2, then time = 3 and last time=4.

Thanks.. :D

*No products are associated with this question.*

Answer by Grzegorz Knor on 7 Oct 2011

Accepted answer

My suggestion:

for k=1:size(val,3) imagesc(val(:,:,k)) colorbar caxis([18 120]) drawnow pause(1) end

Answer by Elige Grant on 7 Oct 2011

If you want to make a movie to use outside of Matlab, then look up "getframe" and something like "movie2avi" in the Navigation Help. For example:

for k=1:size(val,3) handle = imagesc(val(:,:,k)) colorbar caxis([18 120]) save_frame(k) = getframe(handle); end

movie2avi(save_frame,'MyMovie.avi')

You can adjust the rate that frames are displayed per second (see Help for more info).

Walter Manns on 7 Oct 2011

Thanks Grant, very helpfull. The problem is that i see squares changing color, and i can't fin out how to make it smoother. One solution is changing the programming for getting those matrices from 5x5 to 10x10, but i get so much data if i do this i cannot see the results (matlab doesn't let me because they are more than 540,000 data values or something like that). Can i use another plotting form, instead of imagesc, to make a smoother image?

Thanks for the help!

Elige Grant on 7 Oct 2011

Check out "interp2" in the Navigation Help. Instead of calculating and storing a bigger NxN matrix for each time stamp, you might be able to interpolate between the calculated points and use this more dense version for display purposes only.

For N = 5:

[X,Y] = meshgrid(1:5);

[X1,Y1]=meshgrid(1:0.1:5);

handle = imagesc(interp2(X,Y,val(:,:,k),X1,Y1));

Put the definition of X,Y,X1, and Y1 before the for loop... since these do not need to be redefined after each loop iteration.

## 1 Comment

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/17727#comment_39271

The colors should indicate the temperature (120°C should be red, to indicate heat and 18°C blue).