In this question concerning negative signs and the alignment of entries in matrix environments, Heiko Oberdiek gave a great answer in which he uses a user-defined command called
\matminus instead of the usual
How can I define a matrix environment that will automatically perform this replacement of leading negative signs for me?
Thanks for the help!
I have adapted the code provided by Heiko Oberdiek and egreg, and created a package that defines a set of alternate matrix environments (spmatrix, sbmatrix, sBmatrix, svmatrix, and sVmatrix). These environments function analogously to their counterparts without the 's', but reduce the length of the minus signs within them to achieve better alignment of the entries within each column. The project is hosted here.
Here is a picture that shows the difference between the regular and reduced minus matrix environments: