Why can't the sys0 extracted using the convertsys command be processed with collect? However, when I extract its amplitude and then perform collect again, it works. Why is this happening? Is there a good method to handle this? I feel that copying it out is inconvenient for subsequent modifications.

nature_frequency_question.mw

I’m trying to plot a 3D surface in Maple with variables l and m. I used numerical substitution to evaluate the function and the results are real and positive. However, when I plot the function over a range of l and m, the graph shows complex (imaginary) values instead.

This seems very strange to me and has been quite frustrating. I’ve tried many different approaches to resolve the issue, but nothing has worked so far.

Why is this happening? How can the function evaluate to real numbers with direct substitution, but show complex values during plotting?

Any suggestions or explanations would be greatly appreciated. Thank you!
gra423_Omega.mw

I have used plot3d in Maple to generate a 3D plot, but I’m not sure how to export it in high resolution. I tried right-clicking to export the image directly, but the SVG output appeared garbled, and the JPEG version was too low in quality. I also attempted to export the plot using commands, but the resulting image still lacked sufficient resolution. I would like to ask how I can properly export a high-quality 3D figure from Maple.

Commands I have tried：

plotsetup(jpeg, plotoutput = "C:/Users/gfy/Desktop/data5151.jpg", plotoptions = `dpi=1200`);
print(ddd);
plotsetup(default);

I aim to conduct a numerical frequency sweep analysis on a nonlinear, coupled two-degree-of-freedom vibration model and compare the results with the analytical solution. However, I am currently facing two main difficulties:

1. I am unsure how to determine whether the computed response has reached a steady state. If I simply use the maximum value to represent the steady-state amplitude, it can be misleading—since transient responses prior to reaching steady state may yield a higher peak, as seen in the uploaded code.

2. I do not know how to properly select the steady-state result from the previous frequency as the initial condition for the next frequency step.
   2.mw

This time domain diagram has been drawn, but if you want to draw its outer outline, how should you command it?
saopinjifen1230.mw