ejs5.3 and ejss6.0 solvers behave differently (maybe?)
Paul DeYoung
100 Posts
First thank you to wolfgang and fransisco for a prompt response to my recent post. That post was a question asked that I thought would solve the problem below. I apologize for thinking I understood the issue when I should have described the problem.
I am updating a number of our local ejs simulations to ejss. One involving SHO with friction was working strangely. The amplitude of the oscilation would blow up when the friction coefficients were zero (after a few to a few dozen oscillations depending on dt). To probe this I downloaded an EJS sim from the compadre site simple sho - attached in next post) and found that it worked just fine. I made a stripped down EJSS sim (from scratch, also attached) that is, as far as I can tell, functionally equivalent. The amplitude in the EJSS version always grows over time (less so if the dt is made smaller) in contrast to the ejs version that is very stable and insensitive to reasonable changes in dt. I also tried a number of the algorithms and got the same behavior in all that I tried.
I am guessing the basic solver algorithms are the same in 5.3 and 6.0 which leads me to think that I have missed something in the programming, set up, or some option setting.
