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From: Leo Brewin <Leo.Brewin@monash.edu>
Newsgroups: comp.lang.ada
Subject: Re: Real_Arrays on heap with overloaded operators and clean syntax
Date: Mon, 23 Jan 2023 12:14:47 +1100
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Here is a slight variation on the solution suggested by Gautier. It uses 
Aad's "rename" syntax so that you can avoid all the .all stuff. I use 
this construction extensively in my large scale scientific computations.

with Ada.Numerics.Generic_Real_Arrays;
with Ada.Unchecked_Deallocation;

procedure Test_Large is

   type Float_15 is digits 15;

   package F15_R_A is new Ada.Numerics.Generic_Real_Arrays (Float_15);

   use F15_R_A;

   procedure Solve_it
     (x : in     Real_Vector;
      y :    out Real_Vector;
      A : in     Real_Matrix) is
   begin
     null;  --  Here, the big number-crunching
   end;

   n : constant := 10_000;

   type Vector_Access is access Real_Vector;
   type Matrix_Access is access Real_Matrix;

   x_ptr, y_ptr : Vector_Access := new Real_Vector (1 .. n);
   A_ptr        : Matrix_Access := new Real_Matrix (1 .. n, 1 .. n);

   x : Real_Vector renames x_ptr.all;
   y : Real_Vector renames y_ptr.all;
   A : Real_Matrix renames A_ptr.all;

   procedure FreeVector is new
      Ada.Unchecked_Deallocation (Real_Vector,Vector_Access);
   procedure FreeMatrix is new
      Ada.Unchecked_Deallocation (Real_Matrix,Matrix_Access);

begin
   Solve_it (x, y, A);
   -- Deallocation here
   FreeVector (x_ptr);
   FreeVector (y_ptr);
   FreeMatrix (A_ptr);
end;