When running tests, Sin and Cos are invalid tokens but sin and cos are not

When running the test suite, tutorials/t10.geo and tutorials/c++/t10.cpp failed with the error:

libc++abi: terminating due to uncaught exception of type smlib::mathex::error: Error [mathex::parseatom()]: invalid token on expression

However, when Sin and Cos are changed to sin and cos, the error goes away. Any help in figuring out the issue on my system would be greatly appreciated.