math.acos (x) Returns the arc cosine of x (in radians).

math.abs (x) Returns the absolute value of x. (integer/float)

lua_yieldk[-?, +?, e] int lua_yieldk (lua_State *L, int nresults, lua_KContext ctx, lua_KFunction k); Yields a coroutine (thread). When a C function calls lua_yieldk, the running coroutine suspends its execution, and the call to lua_resume that started this coroutine returns. The parameter nresults is the number of values from the stack that will be passed as results to lua_resume. When the coroutine is resumed again, Lua calls the given co

lua_yield[-?, +?, e] int lua_yield (lua_State *L, int nresults); This function is equivalent to lua_yieldk, but it has no continuation (see §4.7). Therefore, when the thread resumes, it continues the function that called the function calling lua_yield.

lua_xmove[-?, +?, –] void lua_xmove (lua_State *from, lua_State *to, int n); Exchange values between different threads of the same state. This function pops n values from the stack from, and pushes them onto the stack to.

lua_Writer typedef int (*lua_Writer) (lua_State *L, const void* p, size_t sz, void* ud); The type of the writer function used by lua_dump. Every time it produces another piece of chunk, lua_dump calls the writer, passing along the buffer to be written (p), its size (sz), and the data parameter supplied to lua_dump. The writer returns an error code: 0 means no errors; any other value means an error and stops lua

lua_version[-0, +0, –] const lua_Number *lua_version (lua_State *L); Returns the address of the version number (a C static variable) stored in the Lua core. When called with a valid lua_State, returns the address of the version used to create that state. When called with NULL, returns the address of the version running the call.

lua_upvaluejoin[-0, +0, –] void lua_upvaluejoin (lua_State *L, int funcindex1, int n1, int funcindex2, int n2); Make the n1-th upvalue of the Lua closure at index funcindex1 refer to the n2-th upvalue of the Lua closure at index funcindex2.

lua_upvalueindex[-0, +0, –] int lua_upvalueindex (int i); Returns the pseudo-index that represents the i-th upvalue of the running function (see §4.4).

lua_upvalueid[-0, +0, –] void *lua_upvalueid (lua_State *L, int funcindex, int n); Returns a unique identifier for the upvalue numbered n from the closure at index funcindex. These unique identifiers allow a program to check whether different closures share upvalues. Lua closures that share an upvalue (that is, that access a same external local variable) will return identical ids for those upvalue indices. Parameters funcindex and n are as in function lua_getupvalue, but n cannot be grea