Fig 6. The repeating module in an LSTM.

Here,x_t and h_t are the input vector and output result to the memory cell at time t, respectively. h_t is the value of the memory cell. i_t, f_t and o_t are values of the input gate, the forget gate and the output gate at time t, respectively. $\widetilde{C_t}$ are values of the the candidate state of the memory cell at time t.