error LNK2019 异常

error LNK2019 错误求助！
Linking...
1>SelfCalib.obj : error LNK2019: unresolved external symbol "void __cdecl kdtree_release(struct kd_node *)" (?kdtree_release@@YAXPAUkd_node@@@Z) referenced in function "public: void __thiscall CSelfCalib::Intr_Paras_Estimation(void)" (?Intr_Paras_Estimation@CSelfCalib@@QAEXXZ)
1>SelfCalib.obj : error LNK2019: unresolved external symbol "struct _IplImage * __cdecl stack_imgs(struct _IplImage *,struct _IplImage *)" (?stack_imgs@@YAPAU_IplImage@@PAU1@0@Z) referenced in function "public: void __thiscall CSelfCalib::Intr_Paras_Estimation(void)" (?Intr_Paras_Estimation@CSelfCalib@@QAEXXZ)
1>SelfCalib.obj : error LNK2019: unresolved external symbol "double __cdecl descr_dist_sq(struct feature *,struct feature *)" (?descr_dist_sq@@YANPAUfeature@@0@Z) referenced in function "public: void __thiscall CSelfCalib::Intr_Paras_Estimation(void)" (?Intr_Paras_Estimation@CSelfCalib@@QAEXXZ)
1>SelfCalib.obj : error LNK2019: unresolved external symbol "int __cdecl kdtree_bbf_knn(struct kd_node *,struct feature *,int,struct feature * * *,int)" (?kdtree_bbf_knn@@YAHPAUkd_node@@PAUfeature@@HPAPAPAU2@H@Z) referenced in function "public: void __thiscall CSelfCalib::Intr_Paras_Estimation(void)" (?Intr_Paras_Estimation@CSelfCalib@@QAEXXZ)
1>SelfCalib.obj : error LNK2019: unresolved external symbol "struct kd_node * __cdecl kdtree_build(struct feature *,int)" (?kdtree_build@@YAPAUkd_node@@PAUfeature@@H@Z) referenced in function "public: void __thiscall CSelfCalib::Intr_Paras_Estimation(void)" (?Intr_Paras_Estimation@CSelfCalib@@QAEXXZ)
1>SelfCalib.obj : error LNK2019: unresolved external symbol "int __cdecl sift_features(struct _IplImage *,struct feature * *)" (?sift_features@@YAHPAU_IplImage@@PAPAUfeature@@@Z) referenced in function "public: void __thiscall CSelfCalib::Intr_Paras_Estimation(void)" (?Intr_Paras_Estimation@CSelfCalib@@QAEXXZ)
1>.\Debug/VCdemo.exe : fatal error LNK1120: 6 unresolved externals


求帮助解答，多谢~~

------解决方案--------------------
在库的实现代码中加extern C试试。
------解决方案--------------------
文件的存放方式有问题，还是没有extern呢？