Help with this MATLAB GUI code

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Bastion on 26 Sep 2011
I'm writing a code for a GUI program and there's something I can't get around.
M = str2double(get(handles.Input_M,'String'));
n = str2double(get(handles.Input_n,'String'));
Vx = str2double(get(handles.Input_Vx,'String'));
Dx = str2double(get(handles.Input_Dx,'String'));
Dy = str2double(get(handles.Input_Dy,'String'));
Dz = str2double(get(handles.Input_Dz,'String'));
t = str2double(get(handles.Input_3D_t,'String'));
X = str2double(get(handles.Input_3D_x,'String')); %%%error
Y = str2double(get(handles.Input_3D_y,'String')); %%%error
Z = str2double(get(handles.Input_3D_z,'String'));
[X,Y] = meshgrid(-10:0.1:10);
C = ((M./n)./(8).*((3.14.*t).^1.5).*sqrt(Dx.*Dy.*Dz)).*exp((-((X-Vx.*t).^2)./4.*Dx.*t)-(Y.^2/4.*Dy.*t)-(Z.^2./4.*Dz.*t)); %%%equation
I let the user input the variables for the equation which will generate a 3D contour. However for X and Y i get the red squiggly line that says "The value assigned to variable X might be unused".
So when I test the program, each different variable would change the contour in someway, however no matter what value I put for X or Y the contour doesn't change! Any ideas?

Answers (3)

Grzegorz Knor
Grzegorz Knor on 26 Sep 2011
In this line:
[X,Y] = meshgrid(-10:0.1:10);
You overwrite X and Y.
Bastion on 27 Sep 2011
How do I change this? Use ()?

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Jan on 27 Sep 2011
After your comment to Grzegorz's answer:
I'm deeply confused about your question, how you could do this. The problem is, that you overwrite an existing definition equivalent to:
X = 3;
X = 4;
You can avoid this by renaming on of the variables, e.g.:
X1 = 3;
X = 4;
X = 3;
X2 = 4;
But this is trivial and the program you've posted looks like you have enough programming skills to find this by your own.
The user can "input any number" for X and Y, so let's assume it is 19 in both cases. Now, how do you want this number to be used "as axis"? Currently you overwrite the values by "[X,Y] = meshgrid(-10:0.1:10);". Perhaps you want something like:
X = linspace(-X, X, 100);
X = -X:0.1:X
  1 Comment
Bastion on 27 Sep 2011
Yes that's what I want I guess, the X and Y defining the dimensions and as variables.
I'm actually only a beginner in Matlab GUI and all I'm doing is looking up the Help guide, not very helpful.
So the meshgrid() is basically setting out the dimensions in my plot? But it's overridding my values, I would be better off with linspace()?

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Bastion on 5 Oct 2011
I tried some of the suggestions but I can't seem to generate a contour anymore. Any ideas?



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