MatrixWritable is not deprecated: https://builds.apache.org//job/Mahout-Quality/javadoc/org/apache/mahout/math/MatrixWritable.html
However, the Matrix type, used by MatrixWritable is deprecated, according to clover: https://builds.apache.org//job/Mahout-Quality/clover/org/apache/mahout/math/matrix/DoubleMatrix2D.html#DoubleMatrix2D I'm confused, can I use MatrixWritable or not?
