As far as I understand it, there's core.matrix which is intended as sort of a universal Clojure API for linear algebra. There are different implementations of the core.matrix API, like the pure JVM vectorz-clj, BLAS based clatrix and even a clojurescript one, aljabr. Incanter uses core.matrix and can therefore use these different implementations. However, the Neanderthal library does not support core.matrix, so Incanter can't use it.
As for why Neanderthal doesn't support core.matrix, I don't know. I see the author is active in this thread, so he can probably give a much better answer, but from reading the mailing lists I gather he mainly created Neanderthal to scratch his own itch, so core.matrix support wasn't a priority.
As for why Neanderthal doesn't support core.matrix, I don't know. I see the author is active in this thread, so he can probably give a much better answer, but from reading the mailing lists I gather he mainly created Neanderthal to scratch his own itch, so core.matrix support wasn't a priority.