code: public static DMatrixRMaj concatRowsMulti(DMatrixRMaj ...m ) {
          int rows = 0;
          int cols = 0;
  
          for (int i = 0; i < m.length; i++) {
              rows += m[i].numRows;
              cols = Math.max(cols,m[i].numCols);
          }
          DMatrixRMaj R = new DMatrixRMaj(rows,cols);
  
          int row = 0;
          for (int i = 0; i < m.length; i++) {
              insert(m[i],R,row,0);
              row += m[i].numRows;
          }
  
          return R;
      }
docs: <p>Concatinates all the matrices together along their columns.  If the rows do not match the upper elements
  are set to zero.</p>
  
  A = [ m[0] ; ... ; m[n-1] ]
  
  @param m Set of matrices
  @return Resulting matrix