}
@Test
public void testGetNumberNNZ() {
vec.set(0, 23);
SparseRealVector casted = (SparseRealVector) vec;
int nnz = casted.getNumberOfNonzero();
Assert.assertEquals(nnz, 1);
vec.set(5, 23);
vec.set(7, 23);
nnz = casted.getNumberOfNonzero();
Assert.assertEquals(nnz, 3);
}