This is the home page of 2x2, the program described in The numerical inversion of functions from the plane to the plane , with Iaci Malta and Carlos Tomei, published in Mathematics of Computation 65, no. 216, 1531-1552 (1996) (you can also get it here). The program tries to find out what the critical set of a smooth function from the plane to the plane looks like: this allows for a graphical global understanding of the function and for very solid inversion.
I am no longer maintaining this program. The person responsible for newer versions of the program is Humberto Bortolossi. Here are two recent versions of the program, which should work in Windows and Linux, and the material of a talk given on November 24th 2006.
wx2x2.2006.11.24.tgz, palestra-2x2.2006.11.24.tgz, wx2x2.2006.09.08.zip.
Here is the last version of the program for which I was directly responsible. The program was then in a very rough state.