我已将库（libxc）安装到本地目录（./configure --prefix=$HOME/materials/mat）中。我适当地更改了环境变量，但是在编译包含libxc的测试代码时遇到以下错误：
(mat) amir@bose test]$ gcc test_libxc.cc
test_libxc.cc:3:10: fatal error: xc.h: No such file or directory
#include <xc.h>
^~~~~~
compilation terminated.
但是xc.h位于/home/amir/materials/mat/include目录中：
(mat) [amir@bose test]$ ls /home/amir/materials/mat/include/
libxc_funcs_m.mod python3.6m/ xc_f03_lib_m.mod xc_f90_lib_m.mod xc_f90_types_m.mod xc_funcs.h xc_funcs_removed.h xc.h xc_version.h
在gcc的搜索目录列表中（下面的第五行）：
(mat) [amir@bose test]$ echo | gcc -E -Wp,-v -
ignoring nonexistent directory "/opt/gcc/7.3.0/lib/gcc/x86_64-pc-linux-gnu/7.3.0/../../../../x86_64-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/home/amir/materials/mat/include
.
/opt/gcc/7.3.0/lib/gcc/x86_64-pc-linux-gnu/7.3.0/include
/usr/local/include
/opt/gcc/7.3.0/include
/opt/gcc/7.3.0/lib/gcc/x86_64-pc-linux-gnu/7.3.0/include-fixed
/usr/include
End of search list.
# 1 "<stdin>"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "<stdin>"
我无法理解这种行为。如果您有任何疑问，请与我们分享。