error with segmentation.cc

@qixuxiang ，你好，我在编译时segmentation.cc报错。

CMakeFiles/ORB_SLAM2.dir/build.make:542: recipe for target 'CMakeFiles/ORB_SLAM2.dir/src/segmentation.cc.o' failed
make[2]: *** [CMakeFiles/ORB_SLAM2.dir/src/segmentation.cc.o] Error 1
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/ORB_SLAM2.dir/all' failed
make[1]: *** [CMakeFiles/ORB_SLAM2.dir/all] Error 2
Makefile:83: recipe for target 'all' failed
make: *** [all] Error 2

出错的地方是：

/home/jin/orb-slam2_with_semantic_label/src/segmentation.cc:129:22: error: ‘isnan’ was not declared in this scope
       if (isnan(theta) | isnan(phi) | isnan(rho)) continue;

请问该如何解决？感激不尽！！！

qixuxiang / orb-slam2_with_semantic_label

error with segmentation.cc #7