unconstrained array type problems

["zork" <zork@nospam.com>]

Hi, i am trying to read a matrix from a text file. For instance if i want to
read in a 2 x 3 matrix, my text file is set up as follows:

-----
2
3
1.0
2.4
3.5
1.2
1.1
2.4
....

I was hoping i could do something like the following (I thought an
unconstrained array is the way to go since i do not know the dimensions of
the array until reading the text file):

------------------
procedure Matrix is

    type Matrix_Type is array ( Integer range <>, Integer range <> ) of
Float;
    ..
    ..
begin
    ..
    Get ( File, number_rows ); -- read the number of rows from file
    Get ( File, number_columns ); -- read the number of columns from file
    array1 : Matrix_Type ( 1 .. number_rows, 1 .. number_columns );
    ..
end Matrix;
------------------

I cant seem to define my array1 in the begin / end block. This is a bit
frustrating. How does one get around this? Is an unconstrained array the
best choice?

Any help most appreciated!

thanks,
zork