[BlockMatrix] multiply is an action or a transformation ?

Hi Everyone, Sorry if the question can be simple, or confusing, but I have not see anywhere in documentation the anwser: Is multiply method in BlockMatrix a transformation or an action. I mean, in order that the multiplication is effectively done it is enough with calling : m1.multiply(m2), Or

Spark SVD benchmark for dense matrices

Hi everyone, I am trying to invert a 5000 x 5000 Dense Matrix (99% non-zeros), by using SVD with an approach simmilar to : https://stackoverflow.com/questions/29969521/how-to-compute-the-inverse-of-a-rowmatrix-in-apache-spark The time Im getting with SVD is close to 10 minutes what is very long