Help with this MATLAB GUI code

Question

Bastion 2011-9-26

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/16744-help-with-this-matlab-gui-code

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
contour3(X,Y,C,100)

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?

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Answer 1

Grzegorz Knor 2011-9-26

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In this line:

[X,Y] = meshgrid(-10:0.1:10);

You overwrite X and Y.

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Grzegorz Knor 2011-9-27

If X and Y will be a scalar values, then C also will be a scalar, and you will not be able to draw a contour plot.

Bastion 2011-9-27

How do I change this? Use ()?

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Answer 2

Jan 2011-9-27

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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;

Or:

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);

Or:

X = -X:0.1:X