Ezimplot3: implicit 3D functions plotter

Plots a 3D surface defined implicitly

Description

At last Matlab do it!!!
Useful tool to plot a 3D implicit surface defined in cartesian coordinates. You can give f(x,y,z) = 0 as a string or as a function handle. Type <help ezimplot3> for usage. Remember to leave your comments and ratings...Thanks!

;)

Acknowledgements

The author wishes to acknowledge the following in the creation of this submission:
implot.m

• Required Products: Symbolic Math Toolbox
• MATLAB release: MATLAB 7.6 (R2008a)

[Tamara Kolda]

This is fantastic! Just what I was looking for and what ezplot3 should do!

One questions/suggestion: Is there a way to also choose the color of the surface that's plotted? I was able to do it manually using the get/set commands, but I was hoping to be able to do it using the function directly.

Thanks for sharing this with the community.

[Gustavo Morales]

I'd like to study ezgraph3 throughly to make -ezimplot3- a "real command", and maybe some day, Mathworks could take it ;)
And...There's a way.... try writing:
>>help ezimplot3
for usage

[Dave Yap]

Dear Gustavo, really nice and neat program.
I would like to plot a DeJong1 test function as below,
f1(x)=sum(x(i)^2), i=1:n, -5.12<=x(i)<=5.12

I'm unable to plot the Dejong1 test function.
Could you pls help me on this?
my email is [e-mail]. Thanks in advance.

[Gustavo Morales]

Dave, as you should know, you only can see plots for explicit R2 to R functions, so the index "i" must be at most 2. Your function is also known as "Parabola", and has this other explicit (not implicit) form:
                  f(x,y) = x^2 + y^2 ... a paraboloid
I suggest that use instead the following command:

>> plotobjective(@dejong1fcn,[-5.12 5.12;-5.12 5.12]);

;-)

[Brian Bak]

Hi

Does anyone no why I can't plot the following:

f = '(x/(400^2 - 0.3*y))^2 + (z/(400^2 - 0.3 *y))^2 -1';
ezimplot3(f,[-3000 3000 -10000 10000 -3000 3000])

It just shows an empty plot from 0 to 1 on all axes. And gives the output: ans = 0.0037

thanks in advance

[Brian Bak]

My mistake it was just the boundaries that where wrong.

[Gustavo Morales]

the numeric answer you get is a handle for the patch object

[Gustavo Morales]

I didn't understand you... so... have you already discovered the mistake? I was trying to do something about it, and that's what I've found:
> f = '(x/(4 - 3*y))^2 + (z/(4 - 3 *y))^2 -1';
> ezimplot3(f,[-3000 3000 -10000 10000 -3000 3000]);

It produces a nice graph... maybe the function that you provided is too small...
Regards!

[Brian Bak]

Hi Gustavo Morales

Just as you wrote the boundaries was not large enough for the surfaces to be plottet.

Do you have any suggestions to how you kan change the surface to be a grid instead of a color?

Thanks in advance.

Very nice program btw!

[Gustavo Morales]

Hi!
> h = ezimplot3() outputs a handle for the patch object. So you can do the folowing:
> set(h,'FaceColor','none','EdgeColor','k')

I hope I have been able to help you.
"I prefer being useful than being important"

[Hisham Moideen]

hi Gustavo,

I have an implicit function, but the variables are alpha, gamma and R.
Can i use ezimplot3() to output my function?

Also is it possible to input different range for my variables like
ezimplot3(M1,[0.2 6 0 5 0 0.34]), will that work?

Appreciate the help and code.

[Gustavo Morales]

Hi...
*fun can be a string, an anonymous function handle, a .M-file handle, an inline function or a symbolic function. Any other variable present at the function (aside from alpha, gamma and R), must have a known value, that is, your function must depend only of alpha, gamma and R.
*>> domain = [min-alpha max-alpha min-gamma max-gamma min-R max-R];
ezimplot3(fun,domain);

test with the examples of help: >> help ezimplot3

regards from Venezuela!

[Hisham Moideen]

hi Gustavo,
I tried plotting the way you suggested.

h1=ezimplot3(M1,[0.02 5 0 4 0 0.35]);

where M1 is the determinant of a matrix involving the three variables alpha,gamma,R.

I got the following error:
"??? Error using ==> ezimplot3 at 82
FUN must have no more than 3 arguments"

To make sure i dont have more than 3 unknowns, i substituted specific values for each and got a single value for my Function M1.

Is is possible that i could send you my code of generating M1 and maybe you could help me.

Problem is my function M1 is not a simple function. Its a determinant of a matrix of order 8. Some of the terms in my matrix is polynomial fit of alpha and R. So the determinant is one crazy looking expression. Matlab cant output my entire determinant value (out of line limit error).

Appreciate any help in this regard!!!

[Gustavo Morales]

Hi Hisham.. ok! send me the code of M1 by email...

[Camilla Colombo]

Dear Gustavo,

thank you for your function. I am trying to plot an implicit function coded into an m. file. However i get an error and i think this is due to the fact that my function contains some "if condition". So I get the error at line 168 of ezimplot3:
f_sym = eval([fun,'(x,y,z)']); % evaluating FUN at the sym point (x,y,z)

do you know a way to avoid this problem?

thank you in advance

Camilla

[Gustavo Morales]

Hi Camilla!
Your funcion has others arguments than x,y,z?
Can you send me the code of your function?... Send it by email...

[Camilla Colombo]

Hi Gustavo,

I sent you an email to [e-mail]
Please let me know if you received it.

Thanks
Camilla

[Gustavo Morales]

Hi Camilla!!! I've already aswered your email...!

[Michelle Gledhill]

Hello Gustavo,
Is there a way to add a contour plot on the x-y-plane in a similar way that the function "surfc" does?
Thank you for your time!

[Jonathan]

This seems like a good function. However, I could not discover it since my time has been fruitlessly spent. This function requires the symbolic toolbox, yet no mention of this was explicitly included on this page or in the function help.

[Gustavo Morales]

Sorry for not being a good software documenter. I'm just a Electrical Engineer .... all the "symbol part" of the code, you can replace it...

[Daniel Lopes]

Nice code! Well done!
You should try to combine it with the implicitplot3d(.)[go this website http://www-users.math.umd.edu/~jmr/241/surfaces.html].
It realy gives an excelent visual result as an alternative to the cranky mesh from isosurface(.) :S.

%% ____________________________________
figure,
syms x y z;
h=x^2+y^2+z^2;
implicitplot3d(h, 1, -3, 3, -3, 3, -3, 3, 40); axis equal
hold on
ezimplot3(h-1,[-5 5])

[Shahab]

Nice Job Gustavo
I just needed an implicit plot in the middle of my code somewhere to show an obstacle...
You saved me a few days of work.
Thx man

[Gkcn]

Dear Gustavo,thank you for your useful function.I tried to use it for plotting my own equation but it gives many surfaces together although i need only one surface around first root of my equation.Please can you help me how can i find it?
my equation is:

tan(sqrt(y)*(1-1/x)*z)-sqrt(y)*(x-z^2)/(x+y)*z=0

1<=x<=10 , 0.1<=y<=10 , 0<=z<=1

Thank you in advance.