!49084 Fix cov error

Merge pull request !49084 from 冯一航/fix_cov_error

docs/api/api_python/ops/mindspore.ops.func_cov.rst

@@ -24,6 +24,9 @@ mindspore.ops.cov
     .. warning::
         `fweights` 和 `aweights` 的值不能为负数，负数权重场景结果未定义。
 
+    .. note::
+        当前暂不支持复数。
+
     参数：
         - **x** (Tensor) - 一个二维矩阵，或单个变量的标量或一维向量。
 

mindspore/python/mindspore/ops/function/math_func.py

@@ -1953,6 +1953,9 @@ def cov(x, *, correction=1, fweights=None, aweights=None):
     .. warning::
         The values of `fweights` and `aweights` cannot be negative, and the negative weight scene result is undefined.
 
+    .. note::
+        Currently, complex number is not supported.
+
     Args:
         x (Tensor): A 2D matrix, or a scalar or 1D vector of a single variable
 
@@ -2028,10 +2031,10 @@ def cov(x, *, correction=1, fweights=None, aweights=None):
         w = None
 
     if w is not None:
-        w_sum = w.sum().astype(mstype.float32)
+        w_sum = w.sum()
         avg = (input_x * w).sum(1) / w_sum
     else:
-        w_sum = Tensor(num_observations, dtype=mstype.float32)
+        w_sum = Tensor(num_observations, dtype=mstype.int64)
         avg = input_x.sum(1) / w_sum
 
     if w is not None and aweights is not None and correction != 0:

tests/st/ops/test_func_cov.py

@@ -43,7 +43,7 @@ def test_cov_normal(mode):
     """
     ms.set_context(mode=mode)
     net = Net()
-    x = ms.Tensor([[0, 2], [1, 1], [2, 0]]).T
+    x = ms.Tensor([[0., 2.], [1., 1.], [2., 0.]]).T
     output1 = net(x)
     expect_output1 = np.array([[1., -1.],
                                [-1., 1.]])

tests/st/tensor/test_cov.py

@@ -42,7 +42,7 @@ def test_cov_normal(mode):
     """
     ms.set_context(mode=mode)
     net = Net()
-    x = ms.Tensor([[0, 2], [1, 1], [2, 0]]).T
+    x = ms.Tensor([[0., 2.], [1., 1.], [2., 0.]]).T
     output1 = net(x)
     expect_output1 = np.array([[1., -1.],
                                [-1., 1.]])