2d array issues

Hello,
Can anyone tell me why the function below is breaking at the second assignment? I am trying to set values for columns 1 and 2 for row 1. The compilation and error are below the function definition. Thanks in advance.

CREATE OR REPLACE 
FUNCTION test() returns void AS $$

declare

    matrix numeric []
[];

    cnt numeric := 1;

begin

    matrix[cnt]
[1] := 3;

    raise notice '%', matrix[cnt
][1];

    matrix[cnt]
[2] := 4;

    raise notice '%', matrix[cnt
][2];

end;

$$ LANGUAGE plpgsql;

 

error...

stocks=# \i test.sql 

CREATE FUNCTION

stocks=# select test();

NOTICE:  3

ERROR:  invalid array subscripts

CONTEXT:  PL/pgSQL FUNCTION "test"
 line 7 at assignment