SELECT array_to_max('{}'::float[]);
 array_to_max 
--------------
             
(1 row)

SELECT array_to_max('{1,1,5,2,0}'::smallint[]);
 array_to_max 
--------------
            5
(1 row)

SELECT array_to_max('{1,1,5,2,0}'::integer[]);
 array_to_max 
--------------
            5
(1 row)

SELECT array_to_max('{1,1,5,2,0}'::bigint[]);
 array_to_max 
--------------
            5
(1 row)

SELECT array_to_max('{1,1,5,2,0}'::real[]);
 array_to_max 
--------------
            5
(1 row)

SELECT array_to_max('{1,1,5,2,0}'::float[]);
 array_to_max 
--------------
            5
(1 row)

SELECT array_to_max('{1,1,5,2,0}'::text[]);
ERROR:  Max subject must be SMALLINT, INTEGER, BIGINT, REAL, or DOUBLE PRECISION values
SELECT array_to_max('{NULL}'::float[]);
 array_to_max 
--------------
             
(1 row)

SELECT array_to_max('{1,1,NULL,2,0}'::float[]);
 array_to_max 
--------------
            2
(1 row)

SELECT array_to_max('{NULL,-1,-1,-2}'::float[]);
 array_to_max 
--------------
           -1
(1 row)

SELECT array_to_max('{-1,-1,-2,NULL}'::float[]);
 array_to_max 
--------------
           -1
(1 row)