CREATE OR REPLACE FUNCTION shortest_path(
sql text,
source_id integer,
target_id integer,
directed boolean,
has_reverse_cost boolean)
RETURNS SETOF path_result
AS '$libdir/librouting'
LANGUAGE 'C' IMMUTABLE STRICT;
When I try to Create a Function like the above I am getting a error like language C Does not exist
Postgres Version 9.3 x86 PostGIS Version - postgis Bundle Version 2.1(with pgrouting 2.0)