code: public void updateRow(int i, double c, Vec b)
      {
          if(b.length() != this.cols())
              throw new ArithmeticException("vector is not of the same column length");
          if (b.isSparse())
              for (IndexValue iv : b)
                  this.increment(i, iv.getIndex(), c * iv.getValue());
          else
              for (int j = 0; j < b.length(); j++)
                  this.increment(i, j, c * b.get(j));
      }
docs: Alters row i of <i>this</i> matrix, such that
  <i>A[i,:] = A[i,:] + c*<b>b</b></i>
  @param i the index of the row to update
  @param c the scalar constant to multiply the vector by
  @param b the vector to add to the specified row