Cohomology.com

The Online Row Reducer. A JavaScript tool teaching the Gauss-Jordan elimination method of row reduction, letting you perform individual row operations, completely row reduce the matrix to row echelon form or reduced row echelon form, or just ask “What do I do next?”. Keeping a stack of all row operations, you can undo them by performing the inverse operations. It also has a separate LU / Inverse Calculator. All computations are performed using rational numbers.

The Linear Algebrator. A Mac OS X application which does everything the online row reducer can, plus the Gram-Schmidt orthogonalization procedure and QR factorization. You can also copy and paste matrices as TeX, and it works offline.

TeXShop. An open-source Mac OS X TeX editor and PDF previewer. I played only a tiny part in the creation of this award-winning program, adding autocompletions (so that, for example, typing “^” gives you “^{}” and typing “...” gives you “\dots”). All the credit goes to Richard Koch, Dirk Olmes, and the long list of contributors.

Cohomology. Here is a PDF file listing the cohomology of a few of my favorite spaces. If you have a favorite space which you would like to see added to my list, please drop me a line, telling me the space, its cohomology (including the ring structure), and the best reference which I can cite or link to. If you are wondering what is this magical thing called cohomology, see Wikipedia for a definition.

If these tools help you with linear algebra, or you like my additions to TeXShop or BibDesk, please consider making a donation to support this site and my efforts. Thank you very much!

Want to hire me? I am available for contract work, consulting, part-time, or full-time work. Please take a look at my resume.

The Adinkramat. If you’ve ever tried quantizing supergravity, you know it’s not easy. Adinkras are diagrams describing supersymmetry, which we believe will help us comprehend our universe. And they also look really cool, all cube-y and fractal-y.

BibDesk Scripts. This AppleScript examines what you are viewing in the front Safari window, and if you are looking at an article on MathSciNet or the Front for the Mathematics ArXiv, it extracts the BibTeX citation data for that article and sends it, along with the text review or abstract, to the front BibDesk window.

Symplectic Geometry Conferences. A web site with upcoming symplectic geometry conferences as well as announcements relevant to the symplectic geometry community. A Wiki, it can be edited by anyone, allowing updates with new conferences without relying on a moderator. Please contribute and spread the word: tell your collaborators and students, and link to it from your own web pages.