Add imag specification for returning the imaginary component of a complex number (#496)

* Add specification for returning the imaginary component for each element of a complex number array

* Update API list

Author: kgryte

spec/API_specification/array_api/elementwise_functions.py

@@ -785,6 +785,21 @@ def greater_equal(x1: array, x2: array, /) -> array:
         an array containing the element-wise results. The returned array must have a data type of ``bool``.
     """
 
+def imag(x: array, /) -> array:
+    """
+    Returns the imaginary component of a complex number for each element ``x_i`` of the input array ``x``.
+
+    Parameters
+    ----------
+    x: array
+        input array. Should have a complex floating-point data type.
+
+    Returns
+    -------
+    out: array
+        an array containing the element-wise results. The returned array must have a floating-point data type with the same floating-point precision as ``x`` (e.g., if ``x`` is ``complex64``, the returned array must have the floating-point data type ``float32``). 
+    """
+
 def isfinite(x: array, /) -> array:
     """
     Tests each element ``x_i`` of the input array ``x`` to determine if finite (i.e., not ``NaN`` and not equal to positive or negative infinity).
@@ -1610,4 +1625,4 @@ def trunc(x: array, /) -> array:
         an array containing the rounded result for each element in ``x``. The returned array must have the same data type as ``x``.
     """
 
-__all__ = ['abs', 'acos', 'acosh', 'add', 'asin', 'asinh', 'atan', 'atan2', 'atanh', 'bitwise_and', 'bitwise_left_shift', 'bitwise_invert', 'bitwise_or', 'bitwise_right_shift', 'bitwise_xor', 'ceil', 'conj', 'cos', 'cosh', 'divide', 'equal', 'exp', 'expm1', 'floor', 'floor_divide', 'greater', 'greater_equal', 'isfinite', 'isinf', 'isnan', 'less', 'less_equal', 'log', 'log1p', 'log2', 'log10', 'logaddexp', 'logical_and', 'logical_not', 'logical_or', 'logical_xor', 'multiply', 'negative', 'not_equal', 'positive', 'pow', 'real', 'remainder', 'round', 'sign', 'sin', 'sinh', 'square', 'sqrt', 'subtract', 'tan', 'tanh', 'trunc']
+__all__ = ['abs', 'acos', 'acosh', 'add', 'asin', 'asinh', 'atan', 'atan2', 'atanh', 'bitwise_and', 'bitwise_left_shift', 'bitwise_invert', 'bitwise_or', 'bitwise_right_shift', 'bitwise_xor', 'ceil', 'conj', 'cos', 'cosh', 'divide', 'equal', 'exp', 'expm1', 'floor', 'floor_divide', 'greater', 'greater_equal', 'imag', 'isfinite', 'isinf', 'isnan', 'less', 'less_equal', 'log', 'log1p', 'log2', 'log10', 'logaddexp', 'logical_and', 'logical_not', 'logical_or', 'logical_xor', 'multiply', 'negative', 'not_equal', 'positive', 'pow', 'real', 'remainder', 'round', 'sign', 'sin', 'sinh', 'square', 'sqrt', 'subtract', 'tan', 'tanh', 'trunc']