Special case NaNs in min/max inputs

Author: honno

spec/API_specification/statistical_functions.md

@@ -24,6 +24,10 @@ Calculates the maximum value of the input array `x`.
 When the number of elements over which to compute the maximum value is zero, the maximum value is implementation-defined. Specification-compliant libraries may choose to error, return a sentinel value (e.g., if `x` is a floating-point input array, return `NaN`), or return the minimum possible value for the input array `x` data type (e.g., if `x` is a floating-point array, return `-infinity`).
 ```
 
+#### Special Cases
+
+-   if `NaN` in elements over which to compute the maximum value, the result is `NaN`.
+
 #### Parameters
 
 -   **x**: _<array>_
@@ -88,6 +92,10 @@ Calculates the minimum value of the input array `x`.
 When the number of elements over which to compute the minimum value is zero, the minimum value is implementation-defined. Specification-compliant libraries may choose to error, return a sentinel value (e.g., if `x` is a floating-point input array, return `NaN`), or return the maximum possible value for the input array `x` data type (e.g., if `x` is a floating-point array, return `+infinity`).
 ```
 
+#### Special Cases
+
+-   if `NaN` in elements over which to compute the minimum value, the result is `NaN`.
+
 #### Parameters
 
 -   **x**: _<array>_