Why does "[x,y,z,v] = image" result in error in MATLAB, where 'image' is a 3D matrix?

There is a predefined double-type matrix named 'flow' in MATLAB with dimensions of 25*50*25. when I want to implement this command in MATLAB:

[x,y,z,v] = flow;

It is ok and there is no problem. But, when I want to perform the same command using a similar hand-made double-type matrix with dimension of 21*101*101 , an error arises:

[x,y,z,v] = image;

Why? Why does it happen?

[DGM]

What error arises? Image() is the name of a built-in function, so if you're shadowing it with something, I can't know how exactly you're doing so.

[Stephen23]

"There is a predefined double-type matrix named 'flow' in MATLAB with dimensions of 25*50*25. when I want to implement this command in MATLAB: [x,y,z,v] = flow; It is ok and there is no problem."

Lets try it right now:

flow = rand(25,50,25);
[x,y,z,v] = flow;

Insufficient number of outputs from right hand side of equal sign to satisfy assignment.

It is not okay and there is a problem.

"Why? Why does it happen?"

Because you are trying to assign one array to four different variables... which makes no sense in MATLAB.

[moh mor]

Hi @DGM , even if I attribute 'image' matrix to another matrix with a particular name, this error happens again:

im234 = image;
[x,y,z,v] = image;

[DGM]

% flow() is a demo file which generates 3D scalar fields
[x,y,z,v] = flow;
slice(x,y,z,v,5,0,0)

[moh mor]

Hi @Stephen23 ,

thank you for your answer. But, do not assign something to flow. just do this:

[x,y,z,v] = flow;

This is enough. do not include this line:

flow = rand(25,50,25);

[DGM]

image() is a function. If you have a matrix that you want to use, just don't call it image.

You can't reassign image() to a new name by doing this assignment:

renamedfunction = image

If you do that, the output is a handle to an image object in the current figure.

It's best to just avoid shadowing functions like that.

[Stephen23]

"But, do not assign something to flow. just do this: [x,y,z,v] = flow;"

Sure, but in that case FLOW is a function, not "a predefined double-type matrix named 'flow' in MATLAB with dimensions of 25*50*25" as you incorrectly wrote in your question. We can easily confirm that FLOW is the name of a function:

which flow -all

/MATLAB/toolbox/matlab/demos/flow.m

Calling functions with multiple outputs is shown in the introductory tutorials:

https://www.mathworks.com/help/matlab/learn_matlab/calling-functions.html

"Why? Why does it happen?"

Misunderstanding what you are working with.

[moh mor]

yes, you are right @Stephen23 . thank you