From 9fc090165524f094ba93393440ecbc9dbdc8c483 Mon Sep 17 00:00:00 2001
From: Jose Luis Blanco-Claraco <joseluisblancoc@gmail.com>
Date: Mon, 18 May 2020 08:30:00 +0200
Subject: [PATCH] more precise use of setZero() and add comments

---
 gtsam/base/SymmetricBlockMatrix.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/gtsam/base/SymmetricBlockMatrix.h b/gtsam/base/SymmetricBlockMatrix.h
index 1ec9a5ad3..c2996109f 100644
--- a/gtsam/base/SymmetricBlockMatrix.h
+++ b/gtsam/base/SymmetricBlockMatrix.h
@@ -71,6 +71,7 @@ namespace gtsam {
     }
 
     /// Construct from a container of the sizes of each block.
+    /// Uninitialized blocks are filled with zeros.
     template<typename CONTAINER>
     SymmetricBlockMatrix(const CONTAINER& dimensions, bool appendOneDimension = false) :
       blockStart_(0)
@@ -81,6 +82,7 @@ namespace gtsam {
     }
 
     /// Construct from iterator over the sizes of each vertical block.
+    /// Uninitialized blocks are filled with zeros.
     template<typename ITERATOR>
     SymmetricBlockMatrix(ITERATOR firstBlockDim, ITERATOR lastBlockDim, bool appendOneDimension = false) :
       blockStart_(0)
@@ -95,7 +97,7 @@ namespace gtsam {
     SymmetricBlockMatrix(const CONTAINER& dimensions, const Matrix& matrix, bool appendOneDimension = false) :
       blockStart_(0)
     {
-      matrix_.setZero(matrix.rows(), matrix.cols());
+      matrix_.resize(matrix.rows(), matrix.cols());
       matrix_.triangularView<Eigen::Upper>() = matrix.triangularView<Eigen::Upper>();
       fillOffsets(dimensions.begin(), dimensions.end(), appendOneDimension);
       if(matrix_.rows() != matrix_.cols())