Hi Guys,

So I'm in no rush to get this question answered but I am certainly struggling trying to wrap my head around this problem.

The Background

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I'll be performing a FRAP experiment as a means to measure a diffusion coefficient. The model I'll be using to determine the tracer diffusion coefficient is the following:

Attachment 18686 Solving this equation will likely be done through Matlab or VBA using a least squares fitting procedure. My issue stems from the two Bessel functions in the equation. I've done some research into them and I can honestly say I'm stumped as to what they are and how to approach a solution to them.

To simplify my question:

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How would one approach a least square fitting procedure to this equation? The Bessel functions are primarily throwing me off. Perhaps there is a simplification which can make my work easier?

The experimental data will output the fluorescence intensity with respect to time. My objective is to find TD, the characteristic diffusion time.