Re: Function in psql to Compare two numbers and return the bigger value

>> I am looking for a psql method to get the bigger value of two numbers.
>>
>> For example,
>>
>> methodName(12.6, 3.8)
>>
> select greatest(12.6,3.8);

It does not work for me,
select greatest(12.6,3.8);
ERROR:  function greatest(numeric, numeric) does not exist
HINT:   No function matches the given name and argument types. You may
need to add explicit type casts.

In 8.1 docs, it says that:
GREATEST(value [, ...])
LEAST(value [, ...])

* Note that GREATEST and LEAST are not in the SQL standard, but are a
common extension. *

Does it mean it is not allowed to use "select greatest(12.6,3.8)" ?

thanks