INFINITE RECURSION with rules...

Hi to everyone.

I've got some problem with rules.

-- I have 2 tables

CREATE TABLE a (email varchar(20), name varchar(10), num1 smallint, num2
smallint, PRIMARY KEY (email, name));

CREATE TABLE b (id smallint PRIMARY KEY, email_a varchar(20), name_a
varchar(10), tot smallint, FOREIGN KEY (email_a, name_a) REFERENCES
a(email, name));

/*

*My goal is to calculate and insert automatically the value of "tot"
when I insert a row into table b.*

*/

-- Some samples

INSERT INTO a VALUES ('mail1(at)email(dot)com
<mailto:%27mail1(at)email(dot)com>','bill',3,5);

INSERT INTO a VALUES ('2mail(at)email(dot)com
<mailto:%272mail(at)email(dot)com>','paul',4,7); <mailto:%27mail1(at)email(dot)com>

-- Then I created a simple function

CREATE OR REPLACE FUNCTION calc(varchar(10), varchar(20)) RETURNS
smallint AS $$

DECLARE

rowww a%ROWTYPE;

BEGIN

SELECT * INTO rowww FROM a WHERE email = $1 AND name = $2;

IF FOUND

THEN RETURN rowww.num1 * rowww.num2;

ELSE

RAISE WARNING 'Error: values non found!';

END IF;

END;

$$ LANGUAGE plpgsql;

-- And this easy rule

CREATE RULE rrr_a_b AS ON INSERT TO b

DO INSTEAD

INSERT INTO b VALUES

(NEW.id,

NEW.email_a,

NEW.name_a,

(SELECT calc(NEW.email_a, NEW.name_a))

);

-- Sample for insert into b

INSERT INTO b VALUES (33,'mail1(at)email(dot)com','bill');

Trying to insert into b (and using the new rule defined by myself, i
receive this message:

/*ERROR: infinite recursion detected in rules for relation "b"*/

How I could solve this problem?