LSTM - 1 vs 7#
Next section compares an older to a newer version of the same operator after both definition are converted into markdown text. Green means an addition to the newer version, red means a deletion. Anything else is unchanged.
- LSTM1 → LSTM7 +8 -7
LSTM1 → LSTM7
RENAMED
@@ -1 +1 @@
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Computes an one-layer LSTM. This operator is usually supported via some
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custom implementation such as CuDNN.
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Notations:
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X - input tensor
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i - input gate
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o - output gate
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f - forget gate
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c - cell gate
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t - time step (t-1 means previous time step)
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W[iofc] - W parameter weight matrix for input, output, forget, and cell gates
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R[iofc] - R recurrence weight matrix for input, output, forget, and cell gates
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Wb[iofc] - W bias vectors for input, output, forget, and cell gates
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Rb[iofc] - R bias vectors for input, output, forget, and cell gates
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P[iof] - P peephole weight vector for input, output, and forget gates
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WB[iofc] - W parameter weight matrix for backward input, output, forget, and cell gates
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RB[iofc] - R recurrence weight matrix for backward input, output, forget, and cell gates
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WBb[iofc] - W bias vectors for backward input, output, forget, and cell gates
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RBb[iofc] - R bias vectors for backward input, output, forget, and cell gates
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PB[iof] - P peephole weight vector for backward input, output, and forget gates
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H - Hidden state
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num_directions - 2 if direction == bidirectional else 1
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Activation functions:
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Relu(x) - max(0, x)
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Tanh(x) - (1 - e^{-2x})/(1 + e^{-2x})
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Sigmoid(x) - 1/(1 + e^{-x})
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(NOTE: Below are optional)
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Affine(x) - alpha*x + beta
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LeakyRelu(x) - x if x >= 0 else alpha * x
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ThresholdedRelu(x) - x if x >= alpha else 0
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ScaledTanh(x) - alpha*Tanh(beta*x)
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HardSigmoid(x) - min(max(alpha*x + beta, 0), 1)
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Elu(x) - x if x >= 0 else alpha*(e^x - 1)
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Softsign(x) - x/(1 + |x|)
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Softplus(x) - log(1 + e^x)
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Equations (Default: f=Sigmoid, g=Tanh, h=Tanh):
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-
- it = f(Xt*(Wi^T) + Ht-1*
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+
- it = f(Xt*(Wi^T) + Ht-1*Ri + Pi (.) Ct-1 + Wbi + Rbi)
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-
- ft = f(Xt*(Wf^T) + Ht-1*
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+
- ft = f(Xt*(Wf^T) + Ht-1*Rf + Pf (.) Ct-1 + Wbf + Rbf)
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-
- ct = g(Xt*(Wc^T) + Ht-1*
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- ct = g(Xt*(Wc^T) + Ht-1*Rc + Wbc + Rbc)
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- Ct = ft (.) Ct-1 + it (.) ct
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-
- ot = f(Xt*(Wo^T) + Ht-1*
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+
- ot = f(Xt*(Wo^T) + Ht-1*Ro + Po (.) Ct + Wbo + Rbo)
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- Ht = ot (.) h(Ct)
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-
This operator has **optional** inputs/outputs. See ONNX <https://github.com/onnx/onnx/blob/master/docs/IR.md>_ for more details about the representation of optional arguments. An empty string may be used in the place of an actual argument's name to indicate a missing argument. Trailing optional arguments (those not followed by an argument that is present) may also be simply omitted.
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**Attributes**
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* **activation_alpha**:
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Optional scaling values used by some activation functions. The
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values are consumed in the order of activation functions, for
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example (f, g, h) in LSTM. Default values are the same as of
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corresponding ONNX operators.For example with LeakyRelu, the default
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alpha is 0.01.
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* **activation_beta**:
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Optional scaling values used by some activation functions. The
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values are consumed in the order of activation functions, for
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example (f, g, h) in LSTM. Default values are the same as of
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corresponding ONNX operators.
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* **activations**:
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A list of 3 (or 6 if bidirectional) activation functions for input,
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output, forget, cell, and hidden. The activation functions must be
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one of the activation functions specified above. Optional: See the
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equations for default if not specified.
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* **clip**:
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Cell clip threshold. Clipping bounds the elements of a tensor in the
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range of [-threshold, +threshold] and is applied to the input of
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activations. No clip if not specified.
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* **direction**:
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Specify if the RNN is forward, reverse, or bidirectional. Must be
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one of forward (default), reverse, or bidirectional.
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* **hidden_size**:
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Number of neurons in the hidden layer
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* **input_forget**:
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Couple the input and forget gates if 1.
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Couple the input and forget gates if 1, default 0.
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* **output_sequence**:
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The sequence output for the hidden is optional if 0. Default 0.
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**Inputs**
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Between 3 and 8 inputs.
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* **X** (heterogeneous) - **T**:
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The input sequences packed (and potentially padded) into one 3-D
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tensor with the shape of [seq_length, batch_size, input_size].
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* **W** (heterogeneous) - **T**:
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The weight tensor for the gates. Concatenation of W[iofc] and
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WB[iofc] (if bidirectional) along dimension 0. The tensor has
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shape [num_directions, 4*hidden_size, input_size].
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* **R** (heterogeneous) - **T**:
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The recurrence weight tensor. Concatenation of R[iofc] and
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RB[iofc] (if bidirectional) along dimension 0. This tensor has
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shape [num_directions, 4*hidden_size, hidden_size].
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* **B** (optional, heterogeneous) - **T**:
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The bias tensor for input gate. Concatenation of [Wb[iofc],
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Rb[iofc]], and [WBb[iofc], RBb[iofc]] (if bidirectional) along
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dimension 0. This tensor has shape [num_directions,
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8*hidden_size]. Optional: If not specified - assumed to be 0.
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* **sequence_lens** (optional, heterogeneous) - **T1**:
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Optional tensor specifying lengths of the sequences in a batch. If
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not specified - assumed all sequences in the batch to have length
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seq_length. It has shape [batch_size].
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* **initial_h** (optional, heterogeneous) - **T**:
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Optional initial value of the hidden. If not specified - assumed to
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be 0. It has shape [num_directions, batch_size, hidden_size].
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* **initial_c** (optional, heterogeneous) - **T**:
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Optional initial value of the cell. If not specified - assumed to be
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0. It has shape [num_directions, batch_size, hidden_size].
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* **P** (optional, heterogeneous) - **T**:
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The weight tensor for peepholes. Concatenation of P[iof] and
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PB[iof] (if bidirectional) along dimension 0. It has shape
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[num_directions, 3*hidde_size]. Optional: If not specified -
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assumed to be 0.
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**Outputs**
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Between 0 and 3 outputs.
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* **Y** (optional, heterogeneous) - **T**:
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A tensor that concats all the intermediate output values of the
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hidden. It has shape [seq_length, num_directions, batch_size,
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-
hidden_size].
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+
hidden_size]. It is optional if output_sequence is 0.
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* **Y_h** (optional, heterogeneous) - **T**:
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The last output value of the hidden. It has shape [num_directions,
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batch_size, hidden_size].
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* **Y_c** (optional, heterogeneous) - **T**:
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The last output value of the cell. It has shape [num_directions,
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batch_size, hidden_size].
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**Type Constraints**
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* **T** in (
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tensor(double),
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tensor(float),
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tensor(float16)
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):
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Constrain input and output types to float tensors.
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* **T1** in (
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tensor(int32)
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):
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Constrain seq_lens to integer tensor.
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