Using version control during software development allows experimentation without worrying about removing the experimental work when it does not pan out. Apple has gone a long way to integrating Subversion into Xcode but their instructions are oriented more towards groups of developers rather than a stand-alone version control for a single developer. There is a much easier and more secure way to use Subversion.

This serial routine computes the QR decomposition of a matrix A in Re^mxn, m > = n, such that