CREATE OR REPLACE FUNCTION checkprofit(numeric, numeric)
  RETURNS numeric AS
$BODY$
DECLARE
 CP numeric;
BEGIN
 SELECT mv.var INTO CP FROM main_variables AS mv WHERE mv.id=1;
 IF (CP is NULL) OR (CP < mv.var) THEN
  CP = mv.var;
 END IF;
 
 IF ($1 is NOT NULL) AND ($2 is NOT NULL) THEN 
  IF $2 > CP THEN
   IF $1 > $2 THEN
    RETURN $1;
   ELSE
    RETURN $2;
   END IF;
  ELSE 
   IF $1 > CP THEN
    RETURN $1;
   ELSE
    RETURN CP;
   END IF; 
  END IF;
 ELSE
  RETURN CP;
 END IF;
 
END; 
$BODY$
  LANGUAGE plpgsql

CREATE OR REPLACE FUNCTION calculatefactureprice(numeric, numeric, numeric)
  RETURNS numeric AS
$BODY$
DECLARE
 CFP numeric;
BEGIN
 IF ($1 is NOT NULL) AND ($2 is NOT NULL) AND ($3 is NOT NULL) THEN
  CFP = Round($1 + ($1*CheckProfit($2, $3)*0.01), 3);
  RETURN CFP;
 ELSE
  RETURN 0; 
 END IF;  
END; 
$BODY$
  LANGUAGE plpgsql

SELECT calculatefactureprice(знач1, знач2)