Undefined reference to `clock_gettime' when install

[touala]

Hi,

I got the following error when installing:

$ g++ -std=c++11 -O3  src/sptree.cpp src/tsne.cpp src/nbodyfft.cpp  -o bin/fast_tsne -pthread -lfftw3 -lm
/tmp/cczspn62.o: In function `TSNE::run(double*, int, int, double*, int, double, double, int, bool, int, int, int, int, double, int, int, double, double*, double*, bool, int, double, int, int)':
tsne.cpp:(.text+0x8698): undefined reference to `clock_gettime'
tsne.cpp:(.text+0x8c8b): undefined reference to `clock_gettime'
tsne.cpp:(.text+0x9be8): undefined reference to `clock_gettime'
collect2: error: ld returned 1 exit status

You can fix that by adding -lrt during compilation.

[linqiaozhi]

Thanks so much! It looks like this is an issue for glibc versions <2.17. So for users with older versions of glibc, this is very helpful.