From b5a091998266e619ad6d99c56bbcc2e3ae26bbb6 Mon Sep 17 00:00:00 2001
From: jingwuOUO <wujing2951@gmail.com>
Date: Tue, 24 Nov 2020 11:57:24 -0500
Subject: [PATCH] Refined error message in subgraphbuilder

---
 gtsam/linear/SubgraphBuilder.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gtsam/linear/SubgraphBuilder.cpp b/gtsam/linear/SubgraphBuilder.cpp
index c6b3ca15f..738c101db 100644
--- a/gtsam/linear/SubgraphBuilder.cpp
+++ b/gtsam/linear/SubgraphBuilder.cpp
@@ -383,7 +383,7 @@ Subgraph SubgraphBuilder::operator()(const GaussianFactorGraph &gfg) const {
   const vector<size_t> tree = buildTree(gfg, forward_ordering, weights);
   if (tree.size() != n - 1) {
     throw std::runtime_error(
-        "SubgraphBuilder::operator() failure: tree.size() != n-1");
+        "SubgraphBuilder::operator() failure: tree.size() != n-1, might caused by disconnected graph");
   }
 
   // Downweight the tree edges to zero.