# HG changeset patch
# User John W. Eaton <jwe@octave.org>
# Date 1295625921 18000
# Node ID a9cf422ed849ac6f4efe4b9cec03b3ec7e2a51fd
# Parent  5ec6aa05638dd34b09a4ec4bb32803a0d6e2b583
avoid apparent bug in ATLAS versions of CHERK/ZHERK

diff --git a/liboctave/CMatrix.cc b/liboctave/CMatrix.cc
--- a/liboctave/CMatrix.cc
+++ b/liboctave/CMatrix.cc
@@ -3754,7 +3754,12 @@
         {
           octave_idx_type lda = a.rows ();
 
-          retval = ComplexMatrix (a_nr, b_nc);
+          // FIXME -- looking at the reference BLAS, it appears that it
+          // should not be necessary to initialize the output matrix if
+          // BETA is 0 in the call to ZHERK, but ATLAS appears to
+          // use the result matrix before zeroing the elements.
+
+          retval = ComplexMatrix (a_nr, b_nc, 0.0);
           Complex *c = retval.fortran_vec ();
 
           const char ctra = get_blas_trans_arg (tra, cja);
diff --git a/liboctave/ChangeLog b/liboctave/ChangeLog
--- a/liboctave/ChangeLog
+++ b/liboctave/ChangeLog
@@ -1,3 +1,8 @@
+2011-01-21  John W. Eaton  <jwe@octave.org>
+
+	* CMatrix.cc (xgemm): Initialize output matrix for call to ZHERK.
+	* fCMatrix.cc (xgemm): Initialize output matrix for call to CHERK.
+
 2011-01-20  John W. Eaton  <jwe@octave.org>
 
 	* Array-b.cc, Array-d.cc, Array-f.cc, Array-util.cc,
diff --git a/liboctave/fCMatrix.cc b/liboctave/fCMatrix.cc
--- a/liboctave/fCMatrix.cc
+++ b/liboctave/fCMatrix.cc
@@ -3750,7 +3750,12 @@
         {
           octave_idx_type lda = a.rows ();
 
-          retval = FloatComplexMatrix (a_nr, b_nc);
+          // FIXME -- looking at the reference BLAS, it appears that it
+          // should not be necessary to initialize the output matrix if
+          // BETA is 0 in the call to CHERK, but ATLAS appears to
+          // use the result matrix before zeroing the elements.
+
+          retval = FloatComplexMatrix (a_nr, b_nc, 0.0);
           FloatComplex *c = retval.fortran_vec ();
 
           const char ctra = get_blas_trans_arg (tra, cja);