只要有人遇到相同的问题，这就是我为解决问题所做的工作.将'mathplot.cpp'和'mathplot.h'复制到项目文件夹，然后通过在Code :: Blocks中选择Project-> Add files to project ...，将这两个文件添加到您的项目中.

Just in case anybody is facing the same problem, this is what I have done to solve the problem. Copy both 'mathplot.cpp' and 'mathplot.h' to the project folder, and add both files to your project by selecting Project->Add files to project... in Code::Blocks.