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From: "Matthew" <matthew.merritt.nospam@utsouthwestern.edu>
Newsgroups: comp.soft-sys.matlab
Subject: need exponential growth function with features
Date: Thu, 5 Nov 2009 22:47:01 +0000 (UTC)
Organization: University of Texas Southwestern Medical
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Hi,

I am trying to model the bolus delivery of a pharmeceutical. Theoretically, the delivery shold look like:

1-exp(-rate*abscissa);

However, we are actually delivering the bolus through a syringe with the plunger being pushed by a human, i.e., it is hardly constant. When I try to model the data, I get back a rate, but the fit doesn't seem to model the data very well. It tends to peak a little early, then last longer than it should. 

I suspect that I need a model for the injection that has more detail associated with it. Is their a function that would produce an exponential growth with small oscillations in it that could be controlled by very few variables? I am trying to use fminsearch, and I don't want to have to search over a large number of parameters to get a decent fit, but I suspect only fitting the rate is insufficient. 

Any ideas?

Thanks