#3 Plotting Eigenvalues and Multipliers

[Anonymous]

In the MatCont GUI after computing a curve there is an option to plot the values of eigenvalues or multipliers. The "Layout->variables on axes" dialog provides me with the possibility to plot the real part of all eigenvalues (Re[All)) at the same time. However, choosing this option and asking for a curve redraw leads to an error message : "error D2: Subscript indices must either be real positive integers or logicals". This happens independent of whether I select to plot the real or imaginary part or the norm of the eigenvalues. Plotting a single eigenvalue works OK. Something similar happens when plotting multipliers.

[Alois Steindl]

I have meanwhile found the reason for this behaviour in the file gui_EP.m
and could eliminate the error for my purposes.
I have already told the maintainers about it, but if the OP is still interested and would like to use this feature, before the distribution is updated, the cure is quite simple:
After the line 441 in gui_EP.m insert:

   ~~~~     
        if (plot2(1,j) > -100000*ndim && plot2(1,j) < -10000*ndim)
            plotall = 1;
            plot2(1,j) = plot2(1,j) + 10000*ndim;
        end 
   ~~~~

and remove the corresponding lines (previously 446ff)

        elseif plot2(1,j) < -10000*ndim
            plotall = 1;
            plot2(1,j) = plot2(1,j) + 10000*ndim;

I guess, that the same correction should be applied in the function label1 in gui_EP.m

[katerina Kaouri]

Hello, I get a similar error message when I try to find the equilibrium branch for x'=r*x-x^2.
The command I am running on GUI is Matcont:Compute:Forward (after I have let it run and settle to a steady state). I also ask for the eigenvalues to be calculated but the computation pauses - without any value given for the evals - and i get the following error message:

Error message:

"Subscript indices must either be real positive integers or logicals.
Error while evaluating TimerFcn for timer 'timer-195'

H must be the handle to a figure or figure descendent.

first point found
tangent vector to first point found"

[Alois Steindl]

Hello,
the error message sounds strange to me, but I am just a user of the
package and don't know the details. I have never come across a function
TimerFcn.
Does this error vanish if you plot only a single eigenvalue?
Which version of matcont do you use?
For 6.1 I have locally modified some functions, to resolve some errors,
which made working with matcont quite frustrating. I could send you the
modified file for dealing with the "All Re[eig]" error.
Best wishes
Alois
Am 19.08.2015 um 12:52 schrieb katerina Kaouri:

Hello, I get a similar error message when I try to find the
equilibrium branch for x'=r*x-x^2.
The command I am running on GUI is Matcont:Compute:Forward (after I
have let it run and settle to a steady state). I also ask for the
eigenvalues to be calculated but the computation pauses - without any
value given for the evals - and i get the following error message:

Error message:

"Subscript indices must either be real positive integers or logicals.
Error while evaluating TimerFcn for timer 'timer-195'

H must be the handle to a figure or figure descendent.

first point found
tangent vector to first point found"

---

[bugs:#3] http://sourceforge.net/p/matcont/bugs/3/ Plotting
Eigenvalues and Multipliers

Status: open
Group:
Created: Thu Jun 17, 2010 02:07 PM UTC by Anonymous
Last Updated: Fri May 15, 2015 10:49 AM UTC
Owner: nobody

In the MatCont GUI after computing a curve there is an option to plot
the values of eigenvalues or multipliers. The "Layout->variables on
axes" dialog provides me with the possibility to plot the real part of
all eigenvalues (Re[All)) at the same time. However, choosing this
option and asking for a curve redraw leads to an error message :
"error D2: Subscript indices must either be real positive integers or
logicals". This happens independent of whether I select to plot the
real or imaginary part or the norm of the eigenvalues. Plotting a
single eigenvalue works OK. Something similar happens when plotting
multipliers.

---

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