Thanks for the help. Adrian's answer is probably the best, most secure way to fix the problem, but I found another solution that avoids explicitly citing a schema (one reason I wanted this is that I wanted code that would install the functions in the current user's schema without explicitly stating who that user is):
CREATE OR REPLACE FUNCTION nest_myfunc(
ts_array TIMESTAMP WITHOUT TIME ZONE[],tz text)
RETURNS float[] AS
$BODY$
SELECT myfunc($1,$2);
$BODY$ LANGUAGE 'sql' IMMUTABLE
SET search_path FROM CURRENT;
This explicitly sets the search_path
to be the same as the one at the time of function creation when running the function.