Alois Steindl

Sorry, I missed to attach the input file in the first post. Here it comes. With kind wishes Alois

Continuation of a P2-orbit in an non-autonomous ODE: How to deal with the gluing conditions

Dear MatCont team, first of all: Merry Christmas, Happy New Year and a quiet and comfortable holiday time! I encountered some problems when playing (again) around with the Mathieu equation: Fixing the excitation amplitude and varying the excitation frequency ny along the trivial solution the program locates the period doubling points and some BPCs, where the Floquet multiplier becomes 1. When trying to find the BPCs in the (a, ny) plane, MatCont throws the error "Not enough input arguments". I guess...

Hello, it is still not clear, what you tried to do: After you obtained the approximate limit cycle, did you tell MatCont, that you are looking for limit cycles? (I think, MatCont automatically selects that choice, after it finds the approximate circle.) Did you select a proper bifucation parameter? Looking at your parameters: w is quite close to w1 and w2. You could try to start at e.g. w=4 and decrease it. Since you have two quite similar modes, I would expect a lot of resonances near w=w1=w2. (PS.:...

Hello, I am not a member of the Matcont team. Your description is quite vague: I guess you have rewritten your differential integral algebraic equation as some regular set of ordinary differential equations (or at least a set of n equations in n unknowns (and some parameters)). If you have found a regular solution (without zero eigenvalues), it should normally work to pass it to MatCont as initial guess and start a continuation. You might have to play around with some continuation settings (initial...

Dear Harry,thank you very much for your kind response and the fast treatment of the problem, I am really impressed.I guess, that it is actually a fault in Matlab on Windows, because the help entry for strsplit in Matlab states that "The substrings specified in delimiter do not appear in the output newStr." so I think I should send a bug report.I am learning coco and could already find a family of periodic solutions containg BPCs and LPCs. I still have to get familiar with the details, but coco makes...

You are guessing right, I use Matlab in Windows. I just tried your suggestion with strncmp and that also works. Thanks again for your efforts! Alois

Dear Jan, thank you very much for your patient treatment of the problem! I put a breakpoint at the end of funend and could observe, that the treatment of the newline character in string functions might be the problem: After splitting the string at the newlines, the newline character remains in the strings, so one gets 'end\n' (actually Matlab 2023b distinguishes between the placeholder '\n' and the actual newline character <nl>, so the second last entry in str is 'end<nl>'. Therefore strcmp gives...