Ventana software support forum

...there's some other software you use that does things differently/better... what I would like to see in Vensim is the possibility to use transfer functions for LTI systems i.e. the possibility to convolve an input with the system's pulse response. (I guess Vensim operates in the time domain only,...

tomfid wrote:...It's then scaled so that (a) the area under the curve is 1 and (b) the mean arrival time is equal to the delay time parameter.

how does 'delay time' do both a) and b) at the same time? what's the math behind it? r

...what happens to the results of the outflow with regard to your expectations, if you put the Delay Time value = the mean delay of your pdf? In the screenshot example below, my 'pdf' peaks at time=11 (unit = 1/4year) . If I set 'delay time' to 11 the results look quite ok. Nevertheless it seems st...

thx for the example, Tom A while ago I have built a very simple model to test my case. It should illustrate the pulse response (Dirac) of the delay function (lookup of a weibull pdf), thus convolving 'in' with the 'pdf'! I have to admit that after playing around with it for a while I still do not un...

thx for all your help Tom,
what would be a great help would be a mathmatical description of the algorithm - 'the formula' . From there it will be easy to figure out the use and setting of the parameters
rolf

this is what I tried but got confused with the parameters 'delay time','init' and 'init grow' - referring to the Vensim Help it seems straight forward ...The delay response is the response that the output will show when given a pulse as an input... = transfer function of an LTI system... Also this s...

thx for the swift reply. My applications are strictly physical and thus causal. Currently I'd like to model end of life behaviour of large numbers of electrical appliances and use various probability density functions (pdf) to shape failure rates (e.g. Weibull distribution). The system behaviour cou...

I'd like to perform a convolution f(t)*g(t) in Vensim (see e.g. http://en.wikipedia.org/wiki/Convolution ). I played around with the DELAY PROFILE function as it looks close to what I need but I couldn't figure out what it actually calculates. Could anyone point me to some help on how to construct a...