code: public static void scaleRow( double alpha , DMatrixRMaj A , int row ) {
          int idx = row*A.numCols;
          for (int col = 0; col < A.numCols; col++) {
              A.data[idx++] *= alpha;
          }
      }
docs: In-place scaling of a row in A
  
  @param alpha scale factor
  @param A matrix
  @param row which row in A