/usr/include/eigen3/Eigen/src/SparseLU/ is in libeigen3-dev 3.2.2-3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLUImpl.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU_Memory.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU_Structs.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU_SupernodalMatrix.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU_Utils.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU_column_bmod.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU_column_dfs.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU_copy_to_ucol.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU_gemm_kernel.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU_heap_relax_snode.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU_kernel_bmod.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU_panel_bmod.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU_panel_dfs.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU_pivotL.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU_pruneL.h
/usr/include/eigen3/Eigen/src/SparseLU/SparseLU_relax_snode.h