3D plot a function f(x,y,z)

I have a function of the coordinates x,y and z like the following :

function f= f(x,y,z)
    if (x>0) & (y<1)    % this is just an example, do whatever you want with the variables
        f= 1;           
    else 
        f= x-y+2*z;
    end
end

That I want to plot like by using the fimplicit3() function :

syms f(x,y,z)
f(x,y,z) = x^2 + y^2 - z^2;
fimplicit3(f)

The problem is fimplicit3 deals with the symbolic variables but fails to take as argument a function that I 'manually' specified above.

Is there another way to plot such a function ?

I just wanna draw some balls in space.

Answer 1

[David Hill]

g=fimplicit3(@f);

function g = f(x,y,z)
  g=1./x.^2 - 1./y.^2 + 1./z.^2;
end

[Omar Keele]

In this case g should not be a surface, I don't understand. Every point in space should have a color assigned to it, the 'value' of the color should be g(x0,y0,z0) for the point (x0,y0,z0).

Maybe the fimplicit3() is not what I am looking for ?

[Torsten]

fimplicit3 plots the surface for which f(x,y,z) = 0.

For your function, this will be impossible for (x>0 & y<1) since f will always be 1 there.

[Omar Keele]

This is not an issue, to draw a line segment in space, take f to be

function f= f(x,y,z)
    if x=1 & y=2 & z<3 & z>-3
        f= 1
    else 
        f=0
    end
end

We can draw isolated points in space if we wish, can't we?

[Torsten]

I think you have a false impression of what fimplicit plots.

[Omar Keele]

I mentioned the fimplicit to illustrate, do you know a matlab command to do this ? Maybe scatter3D?

Something that plot values of f(x,y,z) with different colors, the space should be filled ! (or maybe empty if the value is 0)

[David Hill]

https://www.mathworks.com/help/matlab/visualize/visualizing-four-dimensional-data.html

Answer 2

[Drc]

guys i need this shape code

[DGM]

Start a new question at the "Ask" link at the top of the page. Include enough information so that other people know specifically what you want. Considering that specific details were intentionally omitted from the image, I have to wonder why you're making it difficult.

Otherwise, see cylinder(), patch(), surf()