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Ethiopian multiplication: Difference between revisions
+ version for pl/pgsql
(+ version for pl/pgsql) |
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</lang>
=={{header|PL/pgSQL}}==
Everything encapsulated in one function.
<lang plpgsql>
CREATE OR REPLACE FUNCTION ethiopian_multiplication(multiplier int, multiplicant int) RETURNS int AS $BODY$
-- works at least on PostgreSQL 8.3, should work in older versions as well
DECLARE
sum integer := 0;
plier integer := abs(multiplier);
plicant integer := abs(multiplicant);
BEGIN
-- handling 0 values
IF (multiplier = 0 OR multiplicant = 0) THEN
RAISE NOTICE 'One operand is 0. Result 0.';
RETURN 0;
END IF;
-- running until left operand equals 1
WHILE plier >= 1 LOOP
-- is left operand even?
IF plier % 2 = 0 THEN
-- yes, strike this row
RAISE NOTICE '%, % STRIKE', plier, plicant;
ELSE
-- no, add this row to sum
RAISE NOTICE '%, % KEEP', plier, plicant;
sum = sum + plicant;
END IF;
-- halve left argument
plier = floor(plier/2);
-- double left argument
plicant = plicant*2;
END LOOP;
-- handling negative arguments
IF (multiplier < 0 AND multiplicant > 0) OR (multiplier > 0 AND multiplicant < 0) THEN
RAISE NOTICE 'Handling negative operands. Invert result.';
sum = 0 - sum;
END IF;
RETURN sum;
END;
$BODY$ LANGUAGE 'plpgsql';
</lang>
<lang sql>
SELECT ethiopian_multiplication(17, 34);
</lang>
<lang text>
NOTICE: 17, 34 KEEP
NOTICE: 8, 68 STRIKE
NOTICE: 4, 136 STRIKE
NOTICE: 2, 272 STRIKE
NOTICE: 1, 544 KEEP
ethiopian_multiplication
--------------------------
578
(1 row)
</lang>
=={{header|PowerShell}}==
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