This fixes a precondition failure triggered when the Eigenvalues routine of
Ada.Numerics.Generic_Real_Arrays is instantiated with -gnata, beause it calls
Sort_Eigensystem on an empty vector.
Tested on x86-64/Linux, applied on all active branches.
2024-12-12 Eric Botcazou <ebotca...@adacore.com>
PR ada/117996
* libgnat/a-ngrear.adb (Jacobi): Remove default value for
Compute_Vectors formal parameter.
(Sort_Eigensystem): Add Compute_Vectors formal parameter. Do not
modify the Vectors if Compute_Vectors is False.
(Eigensystem): Pass True as Compute_Vectors to Sort_Eigensystem.
(Eigenvalues): Pass False as Compute_Vectors to Sort_Eigensystem.
2024-12-12 Eric Botcazou <ebotca...@adacore.com>
* gnat.dg/matrix1.adb: New test.
--
Eric Botcazoudiff --git a/gcc/ada/libgnat/a-ngrear.adb b/gcc/ada/libgnat/a-ngrear.adb
index e70617f2096..6778a56e45c 100644
--- a/gcc/ada/libgnat/a-ngrear.adb
+++ b/gcc/ada/libgnat/a-ngrear.adb
@@ -96,7 +96,7 @@ package body Ada.Numerics.Generic_Real_Arrays is
(A : Real_Matrix;
Values : out Real_Vector;
Vectors : out Real_Matrix;
- Compute_Vectors : Boolean := True);
+ Compute_Vectors : Boolean);
-- Perform Jacobi's eigensystem algorithm on real symmetric matrix A
function Length is new Square_Matrix_Length (Real'Base, Real_Matrix);
@@ -107,8 +107,9 @@ package body Ada.Numerics.Generic_Real_Arrays is
-- Perform a Givens rotation
procedure Sort_Eigensystem
- (Values : in out Real_Vector;
- Vectors : in out Real_Matrix);
+ (Values : in out Real_Vector;
+ Vectors : in out Real_Matrix;
+ Compute_Vectors : Boolean);
-- Sort Values and associated Vectors by decreasing absolute value
procedure Swap (Left, Right : in out Real);
@@ -486,7 +487,7 @@ package body Ada.Numerics.Generic_Real_Arrays is
is
begin
Jacobi (A, Values, Vectors, Compute_Vectors => True);
- Sort_Eigensystem (Values, Vectors);
+ Sort_Eigensystem (Values, Vectors, Compute_Vectors => True);
end Eigensystem;
-----------------
@@ -500,7 +501,7 @@ package body Ada.Numerics.Generic_Real_Arrays is
Vectors : Real_Matrix (1 .. 0, 1 .. 0);
begin
Jacobi (A, Values, Vectors, Compute_Vectors => False);
- Sort_Eigensystem (Values, Vectors);
+ Sort_Eigensystem (Values, Vectors, Compute_Vectors => False);
end;
end return;
end Eigenvalues;
@@ -522,7 +523,7 @@ package body Ada.Numerics.Generic_Real_Arrays is
(A : Real_Matrix;
Values : out Real_Vector;
Vectors : out Real_Matrix;
- Compute_Vectors : Boolean := True)
+ Compute_Vectors : Boolean)
is
-- This subprogram uses Carl Gustav Jacob Jacobi's iterative method
-- for computing eigenvalues and eigenvectors and is based on
@@ -731,8 +732,9 @@ package body Ada.Numerics.Generic_Real_Arrays is
----------------------
procedure Sort_Eigensystem
- (Values : in out Real_Vector;
- Vectors : in out Real_Matrix)
+ (Values : in out Real_Vector;
+ Vectors : in out Real_Matrix;
+ Compute_Vectors : Boolean)
is
procedure Swap (Left, Right : Integer);
-- Swap Values (Left) with Values (Right), and also swap the
@@ -748,8 +750,10 @@ package body Ada.Numerics.Generic_Real_Arrays is
procedure Swap (Left, Right : Integer) is
begin
Swap (Values (Left), Values (Right));
- Swap_Column (Vectors, Left - Values'First + Vectors'First (2),
- Right - Values'First + Vectors'First (2));
+ if Compute_Vectors then
+ Swap_Column (Vectors, Left - Values'First + Vectors'First (2),
+ Right - Values'First + Vectors'First (2));
+ end if;
end Swap;
begin
-- { dg-do run }
-- { dg-options "-gnata" }
with Ada.Numerics.Generic_Real_Arrays;
procedure Matrix1 is
package GRA is new Ada.Numerics.Generic_Real_Arrays (real => float);
use GRA;
M : constant Real_Matrix (1..2, 1..2) := ((1.0, 0.0), (0.0, 2.0));
E : constant Real_Vector := Eigenvalues (M);
begin
null;
end;
