a_reductions	pbdDMAT		rowSums, colSums, and the like.
b_matprod	pbdDMAT		Matrix product.
c_solve		pbdDMAT		Matrix inversion and solving systems of equations.
d_svd		pbdDMAT		Singular value decomposition.
e_cholesky	pbdDMAT		Cholesky factorization.
