BUG #19340: Wrong result from CORR() function

The following bug has been logged on the website:

Bug reference: 19340
Logged by: Oleg Ivanov
Email address: o15611(at)gmail(dot)com
PostgreSQL version: 18.1
Operating system: all
Description:

postgres=# SELECT corr( 0.09 , 0.09000001 ) FROM generate_series(1,24) ;
corr
------

(1 row)

postgres=# SELECT corr( 0.09 , 0.09000001 ) FROM generate_series(1,25) ;
corr
---------------------
-0.1877294297321991
(1 row)

postgres=# SELECT corr( 0.09 , 0.09000001 ) FROM generate_series(1,31) ;
corr
----------------------
-0.03366532289960463
(1 row)

postgres=# SELECT corr( 0.09 , 0.09000001 ) FROM generate_series(1,32) ;
corr
----------------------
0.037939234274452456
(1 row)

Another example:

postgres=# SELECT corr( 0.9 , 0.91 ) FROM generate_series(1,36) ;
corr
------

(1 row)

postgres=# SELECT corr( 0.9 , 0.91 ) FROM generate_series(1,37) ;
corr
---------------------
0.37167954745944803
(1 row)

postgres=# SELECT corr( 0.9 , 0.91 ) FROM generate_series(1,113) ;
corr
----------------------
0.022884787550167176
(1 row)

postgres=# SELECT corr( 0.9 , 0.91 ) FROM generate_series(1,114) ;
corr
-----------------------
-0.004981175111303341
(1 row)

In the Oracle Database:
SQL> select corr( 0.09 , 0.09000001 ) FROM (select rownum as id from dual
connect by level <=330);

CORR(0.09,0.09000001)
---------------------

If argument is the constant, function CORR() must give a 0 or NaN.
Consequences of this bug: statistic functions are used to make business
descision. Wrong and completely different results can lead to make mistakes.