I don't know if anyone's reading here any more, but here you go:
https://sourceforge.net/projects/matgts/files/jsmath/
Access "index.html". Some of the programs require at least Firefox 3 or 4, because of , but the one which solves systems of equations should run in earlier versions (and up to the latest one, of course). Easy to use, download and run offline, like JavaScript programs are always supposed to run. For accessing web sites, NetSurf is the best (https://www.netsurf-browser.org/), no JavaScript. JavaScript is a great language, just not online, where it's just a great nuisance.
A JavaScript function which uses Cholesky's method (the program mentioned above uses Gauss elimination) is included here:
https://sourceforge.net/projects/matgts/files/jswall/
The file is "js/chol.js", the comment above the function says how the elements of the matrix should be organized.
Equivalent C functions are also provided. All GPL version 3.
P.S. I tried to post the message with NetSurf and it didn't work, apparently this site has some serious problems, which I find surprising for a site about programming, I would have expected its creators to know something about the subject.