As you mentioned, you can perform A * b, where A is a rowmatrix and b is a local matrix.
>From your email, I figure you want to compute b * A^T. To do this, you can compute C = A b^T, whose result is the transpose of what you were looking for, i.e. C^T = b * A^T. To undo the transpose, you would have transpose C manually yourself. Be careful though, because the result might not have each Row fit in memory on a single machine, which is what RowMatrix requires. This danger is why we didn't provide a transpose operation in RowMatrix natively. To address this and more, there is an effort to provide more comprehensive linear algebra through block matrices, which will likely make it to 1.3: https://issues.apache.org/jira/browse/SPARK-3434 Best, Reza On Mon, Jan 12, 2015 at 6:33 AM, Alex Minnaar <aminn...@verticalscope.com> wrote: > I have a rowMatrix on which I want to perform two multiplications. The > first is a right multiplication with a local matrix which is fine. But > after that I also wish to right multiply the transpose of my rowMatrix with > a different local matrix. I understand that there is no functionality to > transpose a rowMatrix at this time but I was wondering if anyone could > suggest a any kind of work-around for this. I had thought that I might be > able to initially create two rowMatrices - a normal version and a > transposed version - and use either when appropriate. Can anyone think of > another alternative? > > > Thanks, > > > Alex >
