Plot in complex plane - Symbolic toolbox

I'm trying to plot the function of complex variable:

mu:=10;lambda:=mu;n:=100;
f2:=16*mu*n^2/(16*mu*n^2-exp(-9*lambda*(n^2-4*k^2)/(64*n^2)))
plot(f2,Re(k)=0..100,Im(k)=0..100,#3D)

and keep getting this message: Error: unexpected arguments: Re(k) = 0..100, Im(k) = 0..100 [plot::Canvas::new]

what am I doing wrong?

Answer 1

[Paulo Silva]

That doesn't look like MATLAB code, are you using MUPAD instead?

[Alex Ter-Sarkissov]

yes

[Paulo Silva]

My experience with MUPAD is very small, please explain what are you trying to do in the plot so I can try to help you.

I plotted something like this plot(f2,Re(f2),Im(f2),#3D) but doesn't seem to be what you want.

[Paulo Silva]

I managed to crash my MUPAD but what you are looking for might be this plot(f2,Re(f2),Im(f2),k=0..100,#3D) , again my MUPAD experience is very small.

[Alex Ter-Sarkissov]

A contour plot in complex plane, with singularities, something like this:

http://www.wolframalpha.com/input/?i=plot(1%2F(z*(z^2%2B1)*Log(z))

[Alex Ter-Sarkissov]

I tried plot(Im(f2),k=0..100,#3D) and plot(Im(f2),k=I*0..I*100,#3D) instead but is definitely not what I'm having in mind

[Paulo Silva]

sorry but I have no idea how to do it but someone else might, good luck

Answer 2

[Walter Roberson]

mu:=10;lambda:=mu;n:=100;
f2:=16*mu*n^2/(16*mu*n^2-exp(-9*lambda*(n^2-4*(k+j*I)^2)/(64*n^2)));
plotfunc3d(f2,k=0..100,j=0..100);

[Alex Ter-Sarkissov]

this looks a bit better. Is there any way to see a contour plot, since I'm primarily interested in poles. I tried plot::Implicit2d, but didn't get any output.

[Walter Roberson]

You probably need to specify the Contours attribute for Implicit2d . See http://www.mathworks.com/help/toolbox/mupad/plot/ATTRIBUTES_Contours.html

[Alex Ter-Sarkissov]

I don't think so. What I need are poles/singularities in the complex plane, something I can't 'specify' - see my link to Wolfram Alpha above.

[Walter Roberson]

Any particular reason not to specify the contour levels as (say) -1e10 -1e9 -1e8 -1e7 ... 1e7 1e8 1e9 1e10 ?

Having it choose automatic contour levels might be more difficult.

I do not have the Symbolic Toolbox and have not used MuPad graphics myself, so I do not know the standard idioms.

[Alex Ter-Sarkissov]

OK, how do you plot complex functions then?