Undefined Reference To Ceil

That guide is a copy of the one from here & also doesn't reflect some changes that were recently made. The changes came from discussions we had about installing static libs & includes to /usr/local & the potential issues that doing so may cause. Apart from the causes already discussed, “undefined reference” may also occur because of the following reasons. #4) Wrong Project Type. When we specify wrong project types in C IDEs like the visual studio and try to do things that the project does not expect, then, we get “undefined reference”. An alternative situation arises where the source for foo is in a separate source file foo.c (and there's a header foo.h to declare foo that is included in both foo.c and undefinedreference.c). Then the fix is to link both the object file from foo.c and undefinedreference.c, or to compile both the source files. Because ceil is a static method of Math, you always use it as Math.ceil, rather than as a method of a Math object you created (Math is not a constructor).