From e93a0717746c859d85890cc201f5f57ec0bb2449 Mon Sep 17 00:00:00 2001
From: Rasmus Munk Larsen <rmlarsen@google.com>
Date: Wed, 15 Dec 2021 22:00:40 +0000
Subject: [PATCH] Fix a bug introduced in !751.

---
 blas/PackedTriangularMatrixVector.h | 38 +++++++++++++++--------------
 1 file changed, 20 insertions(+), 18 deletions(-)

diff --git a/blas/PackedTriangularMatrixVector.h b/blas/PackedTriangularMatrixVector.h
index 63b76aabc..cc2a9b8cf 100644
--- a/blas/PackedTriangularMatrixVector.h
+++ b/blas/PackedTriangularMatrixVector.h
@@ -31,15 +31,16 @@ struct packed_triangular_matrix_vector_product<Index,Mode,LhsScalar,ConjLhs,RhsS
     typedef typename conj_expr_if<ConjLhs,LhsMap>::type ConjLhsType;
     typedef Map<Matrix<ResScalar,Dynamic,1> > ResMap;
 
-    for (Index i=0; i<size; ++i)
-    {
-      Index s = IsLower&&(HasUnitDiag||HasZeroDiag) ? 1 : 0;
-      Index r = IsLower ? size-i: i+1;
-      if (internal::check_implication(HasUnitDiag||HasZeroDiag, (--r)>0))
-	ResMap(res+(IsLower ? s+i : 0),r) += alpha * cj(rhs[i]) * ConjLhsType(LhsMap(lhs+s,r));
-      if (HasUnitDiag)
-	res[i] += alpha * cj(rhs[i]);
-      lhs += IsLower ? size-i: i+1;
+    for (Index i = 0; i < size; ++i) {
+      Index s = IsLower && (HasUnitDiag || HasZeroDiag) ? 1 : 0;
+      Index r = IsLower ? size - i : i + 1;
+      if (!(HasUnitDiag || HasZeroDiag) || (--r > 0)) {
+        ResMap(res + (IsLower ? s + i : 0), r) += alpha * cj(rhs[i]) * ConjLhsType(LhsMap(lhs + s, r));
+      }
+      if (HasUnitDiag) {
+        res[i] += alpha * cj(rhs[i]);
+      }
+      lhs += IsLower ? size - i : i + 1;
     }
   };
 };
@@ -61,15 +62,16 @@ struct packed_triangular_matrix_vector_product<Index,Mode,LhsScalar,ConjLhs,RhsS
     typedef Map<const Matrix<RhsScalar,Dynamic,1> > RhsMap;
     typedef typename conj_expr_if<ConjRhs,RhsMap>::type ConjRhsType;
 
-    for (Index i=0; i<size; ++i)
-    {
-      Index s = !IsLower&&(HasUnitDiag||HasZeroDiag) ? 1 : 0;
-      Index r = IsLower ? i+1 : size-i;
-      if (internal::check_implication(HasUnitDiag||HasZeroDiag, (--r)>0))
-	res[i] += alpha * (ConjLhsType(LhsMap(lhs+s,r)).cwiseProduct(ConjRhsType(RhsMap(rhs+(IsLower ? 0 : s+i),r)))).sum();
-      if (HasUnitDiag)
-	res[i] += alpha * cj(rhs[i]);
-      lhs += IsLower ? i+1 : size-i;
+    for (Index i = 0; i < size; ++i) {
+      Index s = !IsLower && (HasUnitDiag || HasZeroDiag) ? 1 : 0;
+      Index r = IsLower ? i + 1 : size - i;
+      if (!(HasUnitDiag || HasZeroDiag) || (--r > 0)) {
+        res[i] += alpha * (ConjLhsType(LhsMap(lhs + s, r)).cwiseProduct(ConjRhsType(RhsMap(rhs + (IsLower ? 0 : s + i), r)))).sum();
+      }
+      if (HasUnitDiag) {
+        res[i] += alpha * cj(rhs[i]);
+      }
+      lhs += IsLower ? i + 1 : size - i;
     }
   };
 };