!13986 update the documentation of StridedSlice, Gather, GatherNd, etc. operators.

From: @wangshuide2020
Reviewed-by: @liangchenghui,@wuxuejian
Signed-off-by: @liangchenghui

mindspore/ops/operations/array_ops.py

@@ -806,9 +806,11 @@ class Unique(Primitive):
 
 
 class Gather(PrimitiveWithCheck):
-    """
+    r"""
     Returns a slice of the input tensor based on the specified indices and axis.
 
+    Slices the input tensor base on the indices at specified axis. See the following example for more clear.
+
     Inputs:
         - **input_params** (Tensor) - The shape of tensor is :math:`(x_1, x_2, ..., x_R)`.
           The original Tensor.
@@ -818,7 +820,8 @@ class Gather(PrimitiveWithCheck):
         - **axis** (int) - Specifies the dimension index to gather indices.
 
     Outputs:
-        Tensor, the shape of tensor is :math:`(z_1, z_2, ..., z_N)`.
+        Tensor, the shape of tensor is
+        :math:`input\_params.shape[:axis] + input\_indices.shape + input\_params.shape[axis + 1:]`.
 
     Raises:
         TypeError: If `axis` is not an int.
@@ -835,6 +838,11 @@ class Gather(PrimitiveWithCheck):
         [[ 2.  7.]
          [ 4. 54.]
          [ 2. 55.]]
+        >>> axis = 0
+        >>> output = ops.Gather()(input_params, input_indices, axis)
+        >>> print(output)
+        [[3. 4. 54. 22.]
+         [2. 2. 55.  3.]]
     """
 
     @prim_attr_register
@@ -2890,9 +2898,36 @@ class StridedSlice(PrimitiveWithInfer):
     Starting from the beginning position, the fragment continues adding stride to the index until
     all dimensions are not less than the ending position.
 
+    Given a `input_x[m1, m2, ..., mn]`, `begin`, `end` and `strides` will be vectors of length n.
+
+    In each mask field (`begin_mask`, `end_mask`, `ellipsis_mask`, `new_axis_mask`, `shrink_axis_mask`)
+    the ith bit will correspond to the ith m.
+
+    If the ith bit of `begin_mask` is set, `begin[i]` is ignored and the fullest possible range in that dimension
+    is used instead. `end_mask` is analogous, except with the end range.
+
+    As for a 5*6*7 tensor, `x[2:,:3,:]` is equivalent to `x[2:5,0:3,0:7]`.
+
+    If the ith bit of `ellipsis_mask` is set, as many unspecified dimensions as needed will be inserted between
+    other dimensions. Only one non-zero bit is allowed in `ellipsis_mask`.
+
+    As for a 5*6*7*8 tensor, `x[2:,...,:6]` is equivalent to `x[2:5,:,:,0:6]`.
+    `x[2:,...]` is equivalent to `x[2:5,:,:,:]`.
+
+    If the ith bit of `new_axis_mask` is set, `begin`, `end` and `strides` are ignored and a new length 1
+    dimension is added at the specified position in tthe output tensor.
+
+    As for a 5*6*7 tensor, `x[:2, newaxis, :6]` will produce a tensor with shape (2, 1, 7).
+
+    If the ith bit of `shrink_axis_mask` is set, ith size shrinks the dimension by 1, taking on the value
+    at index `begin[i]`, `end[i]` and `strides[i]` are ignored.
+
+    As for a 5*6*7 tensor, `x[:, 5, :]` will result in `shrink_axis_mask` equal to 4.
+
     Note:
         The stride may be negative value, which causes reverse slicing.
         The shape of `begin`, `end` and `strides` must be the same.
+        `begin` and `end` are zero-indexed. The element of `strides` must be non-zero.
 
     Args:
         begin_mask (int): Starting index of the slice. Default: 0.
@@ -3360,6 +3395,15 @@ class GatherNd(PrimitiveWithInfer):
 
     Using given indices to gather slices from a tensor with a specified shape.
 
+    `indices` is an K-dimensional integer tensor. Supposes it as a (K-1)-dimensional tensor and each element of it
+    defines a slice of `input_x`:
+
+    .. math::
+        output[(i_0, ..., i_{K-2})] = input_x[indices[(i_0, ..., i_{K-2})]]
+
+    The last dimension of `indices` can not more than the rank of `input_x`:
+    :math:`indices.shape[-1] <= input_x.rank`.
+
     Inputs:
         - **input_x** (Tensor) - The target tensor to gather values.
         - **indices** (Tensor) - The index tensor, with int data type.

mindspore/ops/operations/math_ops.py

@@ -1852,6 +1852,9 @@ class Log(PrimitiveWithInfer):
     """
     Returns the natural logarithm of a tensor element-wise.
 
+    .. math::
+        y_i = log_e(x_i)
+
     Inputs:
         - **input_x** (Tensor) - The input tensor. The value must be greater than 0.
 
@@ -3613,6 +3616,9 @@ class Cos(PrimitiveWithInfer):
     """
     Computes cosine of input element-wise.
 
+    .. math::
+        out_i = cos(x_i)
+
     Inputs:
         - **input_x** (Tensor) - The shape of tensor is :math:`(x_1, x_2, ..., x_R)`.
 

mindspore/ops/operations/nn_ops.py

@@ -3715,7 +3715,7 @@ class SigmoidCrossEntropyWithLogits(PrimitiveWithInfer):
 
     Inputs:
         - **logits** (Tensor) - Input logits.
-        - **label** (Tensor) - Ground truth label.
+        - **label** (Tensor) - Ground truth label. With the same shape and type as `logits`.
 
     Outputs:
         Tensor, with the same shape and type as input `logits`.