More FORTRAN 90 like vector operations in PostgreSQL

It is also possible to do element wise operations of a vector and a scalar:

CREATE OR REPLACE FUNCTION public._vectormuls(
    v1 anyarray,
    v2 anyelement)
  RETURNS anyarray AS
$BODY$
DECLARE
BEGIN
if array_ndims(v1) != 1 Then
RAISE EXCEPTION 'Only vectors supported';
end if;

return array(select v.a * v.b from (select unnest(v1) as a, v2 as b) v);
END;
$BODY$
  LANGUAGE plpgsql IMMUTABLE STRICT;

CREATE OPERATOR public.*(
  PROCEDURE = _vectormuls,
  LEFTARG = anyarray,
  RIGHTARG = anyelement);

The runtime of the vector/scalar function is about 60% of the vector/vector variant, so the effort for unnest() clearly dominates the runtime of such functions.

And since the dot product of two vectors is the sum of the partial products, it is as simple as this:

CREATE OR REPLACE FUNCTION public._vectordotprod(
    v1 anyarray,
    v2 anyarray)
  RETURNS anyelement AS
$BODY$
DECLARE
BEGIN
if array_ndims(v1) != 1 OR array_ndims(v2) != 1 Then
RAISE EXCEPTION 'Only vectors supported';
end if;

if array_length(v1,1) != array_length(v2,1)  Then
RAISE EXCEPTION 'Vector size mismatch';
end if;

-- return SUM v.a + v.b from (select unnest(v1) as a, unnest(v2) as b) v; --9.4
-- return SUM(v.a * v.b) from (select unnest(v1) as a, unnest(v2) as b) v; --9.4
return SUM(a*b) from unnest(v1,v2) v (a,b); -- 9.5
END;
$BODY$
  LANGUAGE plpgsql IMMUTABLE STRICT;

CREATE OPERATOR public.+*(
  PROCEDURE = _vectordotprod,
  LEFTARG = anyarray,
  RIGHTARG = anyarray,
  COMMUTATOR = +*);

The operator name should be . or *+, but since PostgreSQL won't allow that, +* was the next best thing that worked...

BTW: I tried the same with sql instead of plpgsql as function language and the timings are the same. So the additional sanity checks and the language overhead effectively costs nothing compared to the unrolling of the vector(s).