From 4dd126c630a37050e9431746b1d5263bb57579db Mon Sep 17 00:00:00 2001
From: Erik Schultheis <erik.schultheis@aalto.fi>
Date: Tue, 30 Nov 2021 17:17:41 +0000
Subject: [PATCH] fixed cholesky with 0 sized matrix (cf. #785)

---
 Eigen/src/Cholesky/LLT_LAPACKE.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Eigen/src/Cholesky/LLT_LAPACKE.h b/Eigen/src/Cholesky/LLT_LAPACKE.h
index d7d75bddc..bde9bcdd5 100644
--- a/Eigen/src/Cholesky/LLT_LAPACKE.h
+++ b/Eigen/src/Cholesky/LLT_LAPACKE.h
@@ -35,7 +35,7 @@
 
 #include "./InternalHeaderCheck.h"
 
-namespace Eigen { 
+namespace Eigen {
 
 namespace internal {
 
@@ -106,7 +106,11 @@ namespace lapacke_llt_helpers {
     template<typename MatrixType>
     static Index blocked(MatrixType& m)
     {
-      eigen_assert(m.rows()==m.cols());
+      eigen_assert(m.rows() == m.cols());
+      if(m.rows() == 0) {
+        return -1;
+      }
+
       /* Set up parameters for ?potrf */
       lapack_int size = convert_index<lapack_int>(m.rows());
       lapack_int StorageOrder = MatrixType::Flags&RowMajorBit?RowMajor:ColMajor;