Adds docstrings for statistical functions

dpctl/tensor/_statistical_functions.py

@@ -162,6 +162,35 @@ def _var_impl(x, axis, correction, keepdims):
 
 
 def mean(x, axis=None, keepdims=False):
+    """mean(x, axis=None, keepdims=False)
+
+    Calculates the arithmetic mean of elements in the input array `x`.
+
+    Args:
+        x (usm_ndarray):
+            input array.
+        axis (Optional[int, Tuple[int, ...]]):
+            axis or axes along which the arithmetic means must be computed. If
+            a tuple of unique integers, the means are computed over multiple
+            axes. If `None`, the mean is computed over the entire array.
+            Default: `None`.
+        keepdims (Optional[bool]):
+            if `True`, the reduced axes (dimensions) are included in the result
+            as singleton dimensions, so that the returned array remains
+            compatible with the input array according to Array Broadcasting
+            rules. Otherwise, if `False`, the reduced axes are not included in
+            the returned array. Default: `False`.
+    Returns:
+        usm_ndarray:
+            an array containing the arithmetic means. If the mean was computed
+            over the entire array, a zero-dimensional array is returned.
+
+            If `x` has a floating-point data type, the returned array will have
+            the same data type as `x`.
+            If `x` has a boolean or integral data type, the returned array
+            will have the default floating point data type for the device
+            where input array `x` is allocated.
+    """
     if not isinstance(x, dpt.usm_ndarray):
         raise TypeError(f"Expected dpctl.tensor.usm_ndarray, got {type(x)}")
     nd = x.ndim
@@ -242,6 +271,40 @@ def mean(x, axis=None, keepdims=False):
 
 
 def var(x, axis=None, correction=0.0, keepdims=False):
+    """var(x, axis=None, correction=0.0, keepdims=False)
+
+    Calculates the variance of elements in the input array `x`.
+
+    Args:
+        x (usm_ndarray):
+            input array.
+        axis (Optional[int, Tuple[int, ...]]):
+            axis or axes along which the variances must be computed. If a tuple
+            of unique integers, the variances are computed over multiple axes.
+            If `None`, the variance is computed over the entire array.
+            Default: `None`.
+        correction (Optional[float, int]):
+            degrees of freedom adjustment. The divisor used in calculating the
+            variance is `N-correction`, where `N` corresponds to the total
+            number of elements over which the variance is calculated.
+            Default: `0.0`.
+        keepdims (Optional[bool]):
+            if `True`, the reduced axes (dimensions) are included in the result
+            as singleton dimensions, so that the returned array remains
+            compatible with the input array according to Array Broadcasting
+            rules. Otherwise, if `False`, the reduced axes are not included in
+            the returned array. Default: `False`.
+    Returns:
+        usm_ndarray:
+            an array containing the variances. If the variance was computed
+            over the entire array, a zero-dimensional array is returned.
+
+            If `x` has a real-valued floating-point data type, the returned
+            array will have the same data type as `x`.
+            If `x` has a boolean or integral data type, the returned array
+            will have the default floating point data type for the device
+            where input array `x` is allocated.
+    """
     if not isinstance(x, dpt.usm_ndarray):
         raise TypeError(f"Expected dpctl.tensor.usm_ndarray, got {type(x)}")
 
@@ -260,6 +323,41 @@ def var(x, axis=None, correction=0.0, keepdims=False):
 
 
 def std(x, axis=None, correction=0.0, keepdims=False):
+    """std(x, axis=None, correction=0.0, keepdims=False)
+
+    Calculates the standard deviation of elements in the input array `x`.
+
+    Args:
+        x (usm_ndarray):
+            input array.
+        axis (Optional[int, Tuple[int, ...]]):
+            axis or axes along which the standard deviations must be computed.
+            If a tuple of unique integers, the standard deviations are computed
+            over multiple axes. If `None`, the standard deviation is computed
+            over the entire array. Default: `None`.
+        correction (Optional[float, int]):
+            degrees of freedom adjustment. The divisor used in calculating the
+            standard deviation is `N-correction`, where `N` corresponds to the
+            total number of elements over which the standard deviation is
+            calculated. Default: `0.0`.
+        keepdims (Optional[bool]):
+            if `True`, the reduced axes (dimensions) are included in the result
+            as singleton dimensions, so that the returned array remains
+            compatible with the input array according to Array Broadcasting
+            rules. Otherwise, if `False`, the reduced axes are not included in
+            the returned array. Default: `False`.
+    Returns:
+        usm_ndarray:
+            an array containing the standard deviations. If the standard
+            deviation was computed over the entire array, a zero-dimensional
+            array is returned.
+
+            If `x` has a real-valued floating-point data type, the returned
+            array will have the same data type as `x`.
+            If `x` has a boolean or integral data type, the returned array
+            will have the default floating point data type for the device
+            where input array `x` is allocated.
+    """
     if not isinstance(x, dpt.usm_ndarray):
         raise TypeError(f"Expected dpctl.tensor.usm_ndarray, got {type(x)}")