Archive for July 2009

four parameter logistic (first pulse only)

Per a suggestion of Dr. Modis, The first logistic pulse is now a four parameter logistic:

\displaystyle p(t) = \frac{\kappa}{ 1 + \exp\left( \frac{\ln(81)}{-\alpha} (t - \beta) \right)} + d

where d is a initial displacement value.
The default constraints on d are zero and zero, so the
default is to fit a three parameter logistic for the first pulse
(i.e. the guessing algorithm will not attempt to guess a displacement)


I have written some preliminary and hopefully helpful documentation. Click “Documentation” in the tab bar above this post.

Comments appreciated.
Please send email to p e r r i n m e y e r _at_ y a h o o _dot_ c o m

copy and paste spreadsheet data!

I figured out the javascript to allow a user to copy data from two columns of a spreadsheet and paste it into the application. I have tested it on google chrome (fastest! - my recommendation ), safari (almost as fast, and firefox (about half the speed).

For this reason I consider the app slightly useful, and so I have decided to call it “beta.”. Click on the “Try LogletLab 3.0″ tab on the top of this page.

I thank the coders at for their helpful answers.