c++ - fatal error: Eigen/Dense: No such file or directory -

i have installed libeigen3-dev in order compile programs using eigen 3. when include file, such eigen/dense error when try run g++:

user@office-debian:~/documents/prog$ g++ src/main.cpp -mmd -std=c++11 in file included src/main.cpp:9:0: src/tdefs.h:16:23: fatal error: eigen/dense: no such file or directory compilation terminated. 

running following line works fine:

g++ -i /usr/include/eigen3/ src/main.cpp -mmd -std=c++11

shouldn't include directory automatically found gcc because installed eigen package through aptitude? why boost , opengl found automatically when install libraries not eigen? (note eigen header-only library, shouldn't matter right?)

running g++ src/main.cpp -mmd -std=c++11 --verbose produces following output:

using built-in specs. collect_gcc=g++ collect_lto_wrapper=/usr/lib/gcc/x86_64-linux-gnu/4.7/lto-wrapper target: x86_64-linux-gnu configured with: ../src/configure -v --with-pkgversion='debian 4.7.2-5' --with-bugurl=file:///usr/share/doc/gcc-4.7/readme.bugs --enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.7 --enable-shared --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --enable-objc-gc --with-arch-32=i586 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu thread model: posix gcc version 4.7.2 (debian 4.7.2-5)  collect_gcc_options='-mmd' '-std=c++11' '-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'  /usr/lib/gcc/x86_64-linux-gnu/4.7/cc1plus -quiet -v -imultiarch x86_64-linux-gnu -mmd main.d -d_gnu_source src/main.cpp -quiet -dumpbase main.cpp -mtune=generic -march=x86-64 -auxbase main -std=c++11 -version -o /tmp/ccoyrpky.s gnu c++ (debian 4.7.2-5) version 4.7.2 (x86_64-linux-gnu)     compiled gnu c version 4.7.2, gmp version 5.0.5, mpfr version 3.1.0-p10, mpc version 0.9 ggc heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu" ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../x86_64-linux-gnu/include" #include "..." search starts here: #include <...> search starts here:  /usr/include/c++/4.7  /usr/include/c++/4.7/x86_64-linux-gnu  /usr/include/c++/4.7/backward  /usr/lib/gcc/x86_64-linux-gnu/4.7/include  /usr/local/include  /usr/lib/gcc/x86_64-linux-gnu/4.7/include-fixed  /usr/include/x86_64-linux-gnu  /usr/include end of search list. gnu c++ (debian 4.7.2-5) version 4.7.2 (x86_64-linux-gnu)     compiled gnu c version 4.7.2, gmp version 5.0.5, mpfr version 3.1.0-p10, mpc version 0.9 ggc heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 compiler executable checksum: 66d178dd81da8c975e003e06d9f5e782 in file included src/main.cpp:9:0: src/tdefs.h:16:23: fatal error: eigen/dense: no such file or directory compilation terminated. 

run compiler --verbose switch:

g++ --verbose ... 

if includes relative 1 of paths shown in output, don't have use -i. depends how gcc has been configured, , depends other stuff installed.

note . typically not in -i paths.

later

after exchanging couple of comments clear /usr/include/eigen3/eigen/dense should include-able #include <eigen/dense>, not #include <eigen3/eigen/dense>. therefore, addition of command line option -i /usr/include/eigen3 mandatory.

whether installation selects install header files directory in 1 of ones compiled gcc, depends on default, decision made distributor, or decision made during installation. i'd "frequently used" header files (boost) placed /usr/local/include while "elitist" stuff better off in directory of own.