Search found 2 matches

by gaulocher
Thu Nov 21, 2013 12:59 pm
Forum: Vensim
Topic: What improvements would you like to see in Vensim?
Replies: 150
Views: 11162927

Re: What improvements would you like to see in Vensim?

I have not found any function for computing the time derivative of a signal, i.e. y = du/dt, where the output y(t) is the time derivative of the input u(t). It would be nice to have a ready-made function for this. The time derivative in a discrete-time setting can be approximated for example using y...
by gaulocher
Thu Nov 21, 2013 12:54 pm
Forum: Vensim
Topic: What improvements would you like to see in Vensim?
Replies: 150
Views: 11162927

Re: What improvements would you like to see in Vensim?

It would be really nice to have a ready-made function for a second-order system (similar to DELAY1 or DELAY1I for a first-order system), i.e. a system behaving according to the following differential equation: T^2*d^2y/dt^2 + 2*D*T*dy/dt + y = u y(t) and u(t) are the output and input of the system, ...