Error of undefined m3dRotationMatrix44

[J C]

My Opengl program included math3d.h. But when m3dRotationMatrix44 is called,
error of undefined reference was shown. Can someone tells me how to fix it? I
also got a copy of math3d.cpp. Would it help, and how? Understand the question
is programming based, but any help is appreciated. Tks.

[cpns]

A header only declares a symbol, it does not provide the definition. You
need to link the appropriate library or compiled object code as well. While a
definition of the function may well exist in math3d.cpp, you would not
normally use a library by compiling and linking the source directly to your
application rather than linking a pre-built library. However a judicious
Google suggests that in this case that is exactly what you need to do. Add
math3d.cpp to your project (you do need to use a project for this).