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Date: Mon, 24 Oct 2022 03:31:18 -0700 (PDT)
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Subject: Re: 2-dimensional view on 1 dimensional array
From: AdaMagica <christ-usch.grein@t-online.de>
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Xref: reader01.eternal-september.org comp.lang.ada:64548
List-Id: <comp.lang.ada>

Your code looks rather ununderstandable to me.
A quick attempt on what you claimed you are trying to do (no guarantee):

generic

  type T is private;

  type T_Array is array (Integer range <>) of T;

package Dim1_to_2 is

  -- type T_Array_2Dim is array (Integer range <>, Integer range <>) of T;

  procedure Set (TA: in T_Array; Row, Num_Row, Col, Num_Col: Positive; Value: T)
    with Pre => Row in 1 .. Num_Row and Col in 1 .. Num_Col and
                Num_Row * Num_col = TA'Length;

end Dim1_to_2;
package body Dim1_to_2 is

  type T_Array_2Dim is array (Integer range <>, Integer range <>) of T;

  procedure Set (TA: in T_Array; Row, Num_Row, Col, Num_Col: Positive; Value: T) is
    TA2: T_Array_2Dim (1 .. Num_Row, 1 .. Num_Col);
    for TA2'Address use TA'Address;
  begin
    if Num_Row * Num_Col /= TA'Length or
       Row not in 1 .. Num_Row or Col not in 1 .. Num_Col then
      raise Constraint_Error;
    end if;
    TA2 (Row, Col) := Value;
  end Set;

end Dim1_to_2;
with Dim1_to_2;

procedure Ausprobieren is

  type A is array (Integer range <>) of Integer;

  X: aliased A (-10 .. 10) := (others => 0);

  package To_2D is new Dim1_to_2 (Integer, A);

begin

  To_2D.Set (X, Row => 2, Num_Row => 7, Col => 1, Num_Col => 3, Value => -1);

  for V of X loop
    Put_Line (V'Image);
  end loop;