alpha release

is an alpha release of a javascript version of Loglet Lab, which fits S-curves of the form:

For a demo, click the buttons labeled “step 1″, “step 2″, and “step 3″ (in that order). That will load the “classic” dataset on the growth of a sunflower, and fit a single S-shaped logistic to it. The data and plots all load on one page, so you have to keep scrolling down. There are other datasets pre-loaded. The data is “live” once loaded, so you can change values and click “step 3″ (fit) with new values.

This “app” is mainly to test browser support and work on the algorithms and plotting, with the eventual goal of turning this into a google spreadsheet widget, but it is actually usable on its own.

I am using a “new” constrained regression algorithm that is inefficient (but robust…). So you really need a cutting edge browser (i.e. google chrome, webkit nightly build, or Firefox 3.1 beta with JIT enabled). I don’t use Microsoft IE, so it probably won’t work on IE. I plan on explaining the regression algorithm in a later post.

This PDF explains a bit about the logistic formulation used and how we do our plots.