This appears to be the git repo. potentiall an awful lot of manual downloading that way, though. Annoyingly seems to depend on a lot, including, indirectly on (drakma) which is a completely different topic. This is a bad sign.
The GNU Scientific Library for Lisp (GSLL) allows you to use the GNU Scientific Library (GSL) from Common Lisp. This library provides a full range of common mathematics operations useful to scientific and engineering applications. The design of the GSLL interface is such that access to most of the GSL library is possible in a Lisp-natural way; the intent is that the user not be hampered by the restrictions of the C language in which GSL has been written. GSLL thus provides interactive use of GSL for getting quick answers, even for someone not intending to program in Lisp. Topics include: roots of polynomials, special functions, vector and matrix operations, permutations, sorting, BLAS support, linear algebra, eigensystems, fast Fourier transforms, quadrature, random numbers, quasi-random sequences, random distributions, statistics, histograms, N-tuples, Monte Carlo integration, simulated annealing, differential equations, interpolation, numerical differentiation, chebyshev approximation, series acceleration, discrete Hankel transforms, root-finding, minimization least-squares fitting, IEEE floating-point, discrete wavelet transforms.