FunctionalMatrixView materializes row vectors in scala shell.
Problem first reported by a user Michael Alton, Intel:
"When I first tried to make a large matrix, I got an out of Java heap space error. I increased the memory incrementally until I got it to work. “export MAHOUT_HEAPSIZE=8000” didn’t work, but “export MAHOUT_HEAPSIZE=64000” did. The question is why do we need so much memory? A 5000x5000 matrix of doubles should only take up ~200MB of space?"
Problem has been narrowed down to not override toString() method in FunctionalMatrixView which causes it to materialize all of the row vectors when run in Mahout Spark Shell.