From 1653528c2b12fdd01738b55ab82ffbe47049c0ba Mon Sep 17 00:00:00 2001
From: julie <julielangou@users.noreply.github.com>
Date: Wed, 9 Feb 2011 19:45:09 +0000
Subject: Fix bug 0074

Post from Alexander Kobotov (INTEL)
In LAPACK 3.3 ?(SY/HE)SV are updated to use TRS2.
The TRS2 requires WORK(N) to operate, whereas in SV requirements for LWORK just to be >=1.
There is no any check in SV if LWORK>=N, the array WORK just passed as it is to TRS2.
So if LWORK<N a crash could occur while executing TRS2 due to overuse of allocated workspace.

I guess for the case of LWORK<N just previsous Level2 based ?(SY/HE)TRS should be used.
---
 SRC/chesv.f | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

(limited to 'SRC/chesv.f')

diff --git a/SRC/chesv.f b/SRC/chesv.f
index 4e41de7b..7fe3efcd 100644
--- a/SRC/chesv.f
+++ b/SRC/chesv.f
@@ -4,7 +4,8 @@
 *  -- LAPACK driver routine (version 3.3.0) --
 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
-*     November 2010
+*     February 2011
+* @generated c
 *
 *     .. Scalar Arguments ..
       CHARACTER          UPLO
@@ -27,7 +28,7 @@
 *     A = U * D * U**H,  if UPLO = 'U', or
 *     A = L * D * L**H,  if UPLO = 'L',
 *  where U (or L) is a product of permutation and unit upper (lower)
-*  triangular matrices, and D is Hermitian and block diagonal with 
+*  triangular matrices, and D is Hermitian and block diagonal with
 *  1-by-1 and 2-by-2 diagonal blocks.  The factored form of A is then
 *  used to solve the system of equations A * X = B.
 *
@@ -88,6 +89,8 @@
 *          The length of WORK.  LWORK >= 1, and for best performance
 *          LWORK >= max(1,N*NB), where NB is the optimal blocksize for
 *          CHETRF.
+*          for LWORK < N, TRS will be done with Level BLAS 2
+*          for LWORK >= N, TRS will be done with Level BLAS 3
 *
 *          If LWORK = -1, then a workspace query is assumed; the routine
 *          only calculates the optimal size of the WORK array, returns
@@ -110,10 +113,10 @@
 *     .. External Functions ..
       LOGICAL            LSAME
       INTEGER            ILAENV
-      EXTERNAL           ILAENV, LSAME
+      EXTERNAL           LSAME, ILAENV
 *     ..
 *     .. External Subroutines ..
-      EXTERNAL           CHETRF, CHETRS2, XERBLA
+      EXTERNAL           XERBLA, CHETRF, ZHETRS, CHETRS2
 *     ..
 *     .. Intrinsic Functions ..
       INTRINSIC          MAX
@@ -162,7 +165,19 @@
 *
 *        Solve the system A*X = B, overwriting B with X.
 *
-         CALL CHETRS2( UPLO, N, NRHS, A, LDA, IPIV, B, LDB, WORK, INFO )
+         IF ( LWORK.LT.N ) THEN
+*
+*        Solve with TRS ( Use Level BLAS 2)
+*
+            CALL ZHETRS( UPLO, N, NRHS, A, LDA, IPIV, B, LDB, INFO )
+*
+         ELSE
+*
+*        Solve with TRS2 ( Use Level BLAS 3)
+*
+            CALL CHETRS2( UPLO,N,NRHS,A,LDA,IPIV,B,LDB,WORK,INFO )
+*
+         END IF
 *
       END IF
 *
-- 
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