The function for matrix multiplication for sparse matrices (gsl_spblas_dgemm) currently only works when both inputs are in column- compressed format. It would be straightforward to expand it to cover also row-compressed matrices (without transposing them).
As well, the spmatrix module supports convertion of coordinates/triplets formats to row- and column-compressed, but it doesn't support convertion from a compressed format to coordinates/triplets. This makes it also problematic to perform basic algebra on matrices which might later get multiplied.
