os.exit ([code [, close]]) Calls the ISO C function exit to terminate the host program. If code is true, the returned status is EXIT_SUCCESS; if code is false, the returned status is EXIT_FAILURE; if code is a number, the returned status is this number. The default value for code is true. If the optional second argument close is true, closes the Lua state before exiting.

debug.setupvalue (f, up, value) This function assigns the value value to the upvalue with index up of the function f. The function returns nil if there is no upvalue with the given index. Otherwise, it returns the name of the upvalue.

luaL_len[-0, +0, e] lua_Integer luaL_len (lua_State *L, int index); Returns the "length" of the value at the given index as a number; it is equivalent to the '#' operator in Lua (see §3.4.7). Raises an error if the result of the operation is not an integer. (This case only can happen through metamethods.)

string.upper (s)

lua_stringtonumber[-0, +1, –] size_t lua_stringtonumber (lua_State *L, const char *s); Converts the zero-terminated string s to a number, pushes that number into the stack, and returns the total size of the string, that is, its length plus one. The conversion can result in an integer or a float, according to the lexical conventions of Lua (see §3.1). The string may have leading and trailing spaces and a sign. If the string is not a valid numeral, returns 0 and pushes nothing. (Note that the

lua_pcallk[-(nargs + 1), +(nresults|1), –] int lua_pcallk (lua_State *L, int nargs, int nresults, int msgh, lua_KContext ctx, lua_KFunction k); This function behaves exactly like lua_pcall, but allows the called function to yield (see §4.7).

lua_setupvalue[-(0|1), +0, –] const char *lua_setupvalue (lua_State *L, int funcindex, int n); Sets the value of a closure's upvalue. It assigns the value at the top of the stack to the upvalue and returns its name. It also pops the value from the stack. Returns NULL (and pops nothing) when the index n is greater than the number of upvalues. Parameters funcindex and n are as in function lua_getupvalue.

math.tan (x) Returns the tangent of x (assumed to be in radians).

3.4.6 – Concatenation The string concatenation operator in Lua is denoted by two dots ('..'). If both operands are strings or numbers, then they are converted to strings according to the rules described in §3.4.3. Otherwise, the __concat metamethod is called (see §2.4).

math.fmod (x, y) Returns the remainder of the division of x by y that rounds the quotient towards zero. (integer/float)