[vslist] Ex-Gaussian Functions in MatLab

[Evan Palmer]

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Hi--

I'm analyzing a huge data set of response time distributions, and I'd 
like to fit ex-gaussian functions to the data. Unfortunately, MatLab 
doesn't have the MLE fit procedure to do this already implemented (as 
it does for the gamma, log-normal, and weibull distributions). I was 
wondering if anyone else has written these functions before I go off 
and re-invent the wheel.

Here's what I'm looking for: As an analogy, there is a family of gamma 
functions that come standard in the Stats Toolbox in MatLab. They 
include functions like:

  gamcdf
  gampdf
  gamfit
  gamrnd
  gaminv

So, what I'm wondering is if anyone has the following functions that 
they're willing to share (replacing 'gam' with 'exg' for ex-gaussian):

  exgfit
  exgrnd

I've already implemented exgcdf and exgpdf (based on code from a 
chapter on RT Distribution fitting by Trish van Zandt), and exginv 
should be easy from there. It's just the ex-gaussian fitting function 
and random number generator functions that I need.

Thanks ahead of time for any help you can offer.

--Evan

PS-- I have looked extensively on the MatLab File Exchange bulletin 
board and haven't been able to find these functions.
_________________________________
Evan McHughes Palmer, Ph.D.
Visual Attention Laboratory
Brigham & Women's Hospital
Harvard Medical School

Phone: 	(617) 768-8819
Fax: 	(617) 768-8816
Email: 	palmer@search.bwh.harvard.edu
Web: 	http://search.bwh.harvard.edu/

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Hi--


I'm analyzing a huge data set of response time distributions, and I'd
like to fit ex-gaussian functions to the data. Unfortunately, MatLab
doesn't have the MLE fit procedure to do this already implemented (as
it does for the gamma, log-normal, and weibull distributions). I was
wondering if anyone else has written these functions before I go off
and re-invent the wheel.


Here's what I'm looking for: As an analogy, there is a family of gamma
functions that come standard in the Stats Toolbox in MatLab. They
include functions like:


 gamcdf

 gampdf

 gamfit

 gamrnd

 gaminv


So, what I'm wondering is if anyone has the following functions that
they're willing to share (replacing 'gam' with 'exg' for ex-gaussian):


 exgfit

 exgrnd


I've already implemented exgcdf and exgpdf (based on code from a
chapter on RT Distribution fitting by Trish van Zandt), and exginv
should be easy from there. It's just the ex-gaussian fitting function
and random number generator functions that I need.


Thanks ahead of time for any help you can offer.


--Evan


PS-- I have looked extensively on the MatLab File Exchange bulletin
board and haven't been able to find these functions.<fontfamily><param>Verdana</param>

</fontfamily>_________________________________

<bold>Evan McHughes Palmer, Ph.D.</bold>

Visual Attention Laboratory

Brigham & Women's Hospital

Harvard Medical School


Phone: 	(617) 768-8819

Fax: 	(617) 768-8816

Email: 	palmer@search.bwh.harvard.edu

Web: 	http://search.bwh.harvard.edu/


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