𝛑 - shape Selfstarter func combined from 2 S-shape SelfStarter functions

[ferk88]

Hello, Fernando!
I want to ask you about your plans about new SelfStarter functions: have you intention to add new 𝛑 - shape Selfstarter func combined from your 2 S-shape declined logistic SelfStarter functions to your SelfStarter functions list? I ask this, because time to time you add in repository new selfstarters and your perfectly robust sdlf fucntion allow to fit my rat baroreflex data with nlme mixed models(thank's a lot! https://doi.org/10.1134/S0022093024050338).
This examples of my data. It's reaction of left heart diastolic volume of rat to switch breathing gas mixture from normoxic to hypoxic and and again to normoxic. Solid verticle line in zero represent start of hypoxia, change in shape of points from circle to triangle represent end of hypoxia (so, I have start values for x-axis breakpoints).





Is it difficult to make this 𝛑 - shape Selfstarter?
Now I model my data separatedly for hypoxia and recovery from hypoxia with your sdlf selfstarter(raw):

modeled:

Sincerely yours, Alexander Abramov!

[femiguez]

@ferk88 Would you want to provide more details about the function? I see the data you are trying to model and maybe there is a 'classic' nonlinear function that works. However, it looks like gams (as in mgcv package) could be a solid option for this. Let me know