I am getting a mistake from the deterministic PG function that appears dependent according to after i refer to it as inside a query.

The function is:

CREATE OR REPLACE FUNCTION ircm(starting_money numeric, value numeric, days numeric)
RETURNS numeric
AS $$
BEGIN
-- Calculate effective interest rate, compounded monthly.
    RETURN 12*(pow((value/starting_money),(1./(12.*(days/365.)))) - 1);
END;
$$ LANGUAGE plpgsql;

Basically refer to it as inside a simple Choose statement, it really works fine:

SELECT ircm(100.00,60.427500643787215,30)
Result: -4.79925436505569765596

However, after i run that identical call from the different Choose statement utilizing a subquery:

SELECT
    ircm(100.00,m.v::numeric,30) AS result
FROM(
    SELECT 60.427500643787215 AS v
) m

I recieve the mistake:

ERROR:  a negative number raised to a non-integer power yields a complex result
CONTEXT:  PL/pgSQL function "ircm" line 6 at RETURN

Because the calls are realistically equivalent, just how can PG be coming back a mistake for just one call, although not another? I have ensured there's just one meaning of the function "ircm" during my database. I have attempted shedding/adding it again to make certain PG is not in some way caching a corrupted definition.

Which version as well as on which platform is the database running?

Perhaps you have attempted spinning the function in SQL:

CREATE OR REPLACE FUNCTION ircm(numeric, numeric, numeric)
RETURNS numeric AS $$
    select 12 * (pow(($2 / $1), (1. / (12.* ($3 / 365.)))) - 1);
$$ LANGUAGE sql immutable;

I am running v8.4.4 on Solaris, Linux, and Mac OS X and get exactly the same is a result of your plpgsql (and my SQL) version known as directly, and from inside the subquery.