luajit vs C performance, unexplainable difference ?

[Ico <lua@...>]

Hello,

Below I attached to small programs simply calculating sine tables, one Lua
version and one in C with - as far as I can see - the exact same
implementation.

I have some problems explaining the difference in running time:

plain lua:            4.061s
luajit 2.0.0 beta 8:  0.076s
gcc -O3:              1.480s 

Can onyone shed some light on why the C implementation is more then 20 (!) times
slower then the luajit version ?

I'm testing on a Intel Core 2 Duo CPU @ 2.20GHz. Could this be some kind of
architectural issue ?

-- test.lua ----------------------------------------------------------

local N = 4000
local S = 1000

local t = {}

for i = 0, N do
	t[i] = {
		a = 0,
		b = 1,
		f = i * 0.25
	}
end

for j = 0, S-1 do
	for i = 0, N-1 do
		t[i].a = t[i].a + t[i].b * t[i].f
		t[i].b = t[i].b - t[i].a * t[i].f
	end
	print(string.format("%.6f", t[1].a))
end


-- test.c ------------------------------------------------------------

#include <stdio.h>

#define N 4000
#define S 1000

struct t {
	double a, b, f;
};

int main(int argc, char **argv)
{
	int i, j;
	struct t t[N];

	for(i=0; i<N; i++) {
		t[i].a = 0;
		t[i].b = 1;
		t[i].f = i * 0.25;
	};

	for(j=0; j<S; j++) {
		for(i=0; i<N; i++) {
			t[i].a += t[i].b * t[i].f;
			t[i].b -= t[i].a * t[i].f;
		}
		printf("%.6f\n", t[1].a);
	}

	return 0;
}
-- 
:wq
^X^Cy^K^X^C^C^C^C