On 11/29/06, Tamas K Papp <[EMAIL PROTECTED]> wrote: > I have a sparse Matrix (kronecker product of spline design matrices), > and I need to multiply each row by a number to get another matrix. If > the matrix is A and the numbers are stored in a vector k, with plain > vanilla matrices I would do
> A*k > But when using the Matrix package (class of A is "dgCMatrix"), I get > the warning "coercing sparse to dense matrix for arithmetic". The > error message is perfectly reasonable, I am looking for a way to do it > right (keeping operations in the realm of sparse matrices). Any help > would be appreciated. I would suggest premultiplying by a diagonal matrix. However, when I look at the method dispatch after an example it doesn't appear to be making a good choice. What I think should work well (and Martin or I will make the necessary changes to ensure that it does) is library(Matrix) data(KNex); mm <- KNex$mm system.time(Diagonal(x = rnorm(nrow(mm))) %*% mm) ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel