import org.apache.mahout.math.DenseMatrix; import org.apache.mahout.math.Matrix; Matrix grades = new DenseMatrix(5, 3); import org.apache.mahout.math.stats.OnlineSummarizer; OnlineSummarizer summarizer = new OnlineSummarizer(); for (int i = 0; i < grades.rowSize(); i++) { for (int j = 0; j < grades.columnSize(); j++) { summarizer.add(grades.get(i, j)); } }