v3.0 on linux: undefined reference to `cv::Mat::

I cannot get v3.0 to compile on linux: cameradatafeed.cpp:676: error: undefined reference to `cv::Mat::convertTo(cv::_OutputArray const&, int, double, double) const' I do have the following necessary files included where these references are defined: cameradatafeed.h, opencv.hpp, mat.hpp etc.