BUG #18390: exponentiation produces float datatype, but nth-root produces integer

The following bug has been logged on the website:

Bug reference:      18390
Logged by:          Robb Allan
Email address:      robb@helical.com
PostgreSQL version: 15.5
Operating system:   Mac OS Sonoma 14.3.1 (23D60)
Description:

An exponentiation from a float produces a floating point result:

funds=# select (1.1^10);
      ?column?      
--------------------
 2.5937424601000000
(1 row)

However, an nth-root calculation from that float result does NOT produce a
new float result:

funds=# select (2.5937424601000000^(1/10));
      ?column?      
--------------------
 1.0000000000000000
(1 row)


Only when the root factors are floats does the result coerce to a float:

funds=# select (2.5937424601000000^(1.0/10));
        ?column?        
------------------------
 1.10000000000000000000
(1 row)

funds=# select (2.5937424601000000^(1/10.0));
        ?column?        
------------------------
 1.10000000000000000000
(1 row)