From 063ccf0a1d17ed78f527c5b2c6b16ffcdb738588 Mon Sep 17 00:00:00 2001
From: Julien Schueller <schueller@phimeca.com>
Date: Sat, 13 Jun 2026 12:52:10 +0200
Subject: [PATCH] *chklq: fix test failures when NB=1 with M=N

The LQ test drivers (dchklq, schklq, cchklq, zchklq) called DGELS/SGELS
which re-factorizes AF internally using GEQRF when M>=N. This corrupted
the LQ factorization expected by subsequent LQT02/LQT03 calls on later
K iterations, causing test(1) and test(2) failures.

Fix by re-copying A to AF and re-factorizing with GELQF after the GELS
call, restoring the LQ factorization for the remaining tests.

Closes #973
---
 TESTING/LIN/cchklq.f | 11 +++++++++--
 TESTING/LIN/dchklq.f | 11 +++++++++--
 TESTING/LIN/schklq.f | 11 +++++++++--
 TESTING/LIN/zchklq.f | 11 +++++++++--
 4 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/TESTING/LIN/cchklq.f b/TESTING/LIN/cchklq.f
index c400bdf7b..4cad45861 100644
--- a/TESTING/LIN/cchklq.f
+++ b/TESTING/LIN/cchklq.f
@@ -395,12 +395,19 @@ SUBROUTINE CCHKLQ( DOTYPE, NM, MVAL, NN, NVAL, NNB, NBVAL, NXVAL,
                            CALL CLACPY( 'Full', M, N, A, LDA, AF, LDA )
 *
                            SRNAMT = 'CGELS'
-                           CALL CGELS( 'No transpose', M, N, NRHS, AF,
+                            CALL CGELS( 'No transpose', M, N, NRHS, AF,
      $                                 LDA, X, LDA, WORK, LWORK, INFO )
 *
+*                          Re-factorize AF with CGELQF for subsequent
+*                          LQ tests which expect LQ factorization in AF.
+*
+                            CALL CLACPY( 'Full', M, N, A, LDA, AF, LDA )
+                            CALL CGELQF( M, N, AF, LDA, TAU, WORK,
+     $                                   LWORK, INFO )
+*
 *                          Check error code from CGELS.
 *
-                           IF( INFO.NE.0 )
+                            IF( INFO.NE.0 )
      $                        CALL ALAERH( PATH, 'CGELS', INFO, 0, 'N',
      $                                     M, N, NRHS, -1, NB, IMAT,
      $                                     NFAIL, NERRS, NOUT )
diff --git a/TESTING/LIN/dchklq.f b/TESTING/LIN/dchklq.f
index 0b5daca99..acfdab48c 100644
--- a/TESTING/LIN/dchklq.f
+++ b/TESTING/LIN/dchklq.f
@@ -398,12 +398,19 @@ SUBROUTINE DCHKLQ( DOTYPE, NM, MVAL, NN, NVAL, NNB, NBVAL, NXVAL,
                            CALL DLACPY( 'Full', M, N, A, LDA, AF, LDA )
 *
                            SRNAMT = 'DGELS'
-                           CALL DGELS( 'No transpose', M, N, NRHS, AF,
+                            CALL DGELS( 'No transpose', M, N, NRHS, AF,
      $                                 LDA, X, LDA, WORK, LWORK, INFO )
 *
+*                          Re-factorize AF with DGELQF for subsequent
+*                          LQ tests which expect LQ factorization in AF.
+*
+                            CALL DLACPY( 'Full', M, N, A, LDA, AF, LDA )
+                            CALL DGELQF( M, N, AF, LDA, TAU, WORK,
+     $                                   LWORK, INFO )
+*
 *                          Check error code from DGELS.
 *
-                           IF( INFO.NE.0 )
+                            IF( INFO.NE.0 )
      $                        CALL ALAERH( PATH, 'DGELS', INFO, 0, 'N',
      $                                     M, N, NRHS, -1, NB, IMAT,
      $                                     NFAIL, NERRS, NOUT )
diff --git a/TESTING/LIN/schklq.f b/TESTING/LIN/schklq.f
index d8be9862b..5fecc1ca6 100644
--- a/TESTING/LIN/schklq.f
+++ b/TESTING/LIN/schklq.f
@@ -395,12 +395,19 @@ SUBROUTINE SCHKLQ( DOTYPE, NM, MVAL, NN, NVAL, NNB, NBVAL, NXVAL,
                            CALL SLACPY( 'Full', M, N, A, LDA, AF, LDA )
 *
                            SRNAMT = 'SGELS'
-                           CALL SGELS( 'No transpose', M, N, NRHS, AF,
+                            CALL SGELS( 'No transpose', M, N, NRHS, AF,
      $                                 LDA, X, LDA, WORK, LWORK, INFO )
 *
+*                          Re-factorize AF with SGELQF for subsequent
+*                          LQ tests which expect LQ factorization in AF.
+*
+                            CALL SLACPY( 'Full', M, N, A, LDA, AF, LDA )
+                            CALL SGELQF( M, N, AF, LDA, TAU, WORK,
+     $                                   LWORK, INFO )
+*
 *                          Check error code from SGELS.
 *
-                           IF( INFO.NE.0 )
+                            IF( INFO.NE.0 )
      $                        CALL ALAERH( PATH, 'SGELS', INFO, 0, 'N',
      $                                     M, N, NRHS, -1, NB, IMAT,
      $                                     NFAIL, NERRS, NOUT )
diff --git a/TESTING/LIN/zchklq.f b/TESTING/LIN/zchklq.f
index 7afe70c6c..31a2ee673 100644
--- a/TESTING/LIN/zchklq.f
+++ b/TESTING/LIN/zchklq.f
@@ -395,12 +395,19 @@ SUBROUTINE ZCHKLQ( DOTYPE, NM, MVAL, NN, NVAL, NNB, NBVAL, NXVAL,
                            CALL ZLACPY( 'Full', M, N, A, LDA, AF, LDA )
 *
                            SRNAMT = 'ZGELS'
-                           CALL ZGELS( 'No transpose', M, N, NRHS, AF,
+                            CALL ZGELS( 'No transpose', M, N, NRHS, AF,
      $                                 LDA, X, LDA, WORK, LWORK, INFO )
 *
+*                          Re-factorize AF with ZGELQF for subsequent
+*                          LQ tests which expect LQ factorization in AF.
+*
+                            CALL ZLACPY( 'Full', M, N, A, LDA, AF, LDA )
+                            CALL ZGELQF( M, N, AF, LDA, TAU, WORK,
+     $                                   LWORK, INFO )
+*
 *                          Check error code from ZGELS.
 *
-                           IF( INFO.NE.0 )
+                            IF( INFO.NE.0 )
      $                        CALL ALAERH( PATH, 'ZGELS', INFO, 0, 'N',
      $                                     M, N, NRHS, -1, NB, IMAT,
      $                                     NFAIL, NERRS, NOUT )