https://manpages.ubuntu.com/manpages/xenial/man3/Tcl_GetMathFuncInfo.3tcl.html
Ubuntu Manpage: Tcl_CreateMathFunc, Tcl_GetMathFuncInfo, Tcl_ListMathFuncs - Define, query and...
Define, query and enumerate math functions for expressions
ubuntumanpagetcldefinequery