static int cdf_dpois (lua_State *L) {
/* stack should contain s and xlam */
lua_Number s = luaL_checknumber(L, 1);
lua_Number xlam = luaL_checknumber(L, 2);
lua_Number d;
check_pois(L, 1, s, xlam);
d = s+1;
d = exp(s*log(xlam)-xlam-dlngam(&d));
lua_pushnumber(L, d);
return 1;
}
static int stat_ppois (lua_State *L) {
/* stack should contain s and xlam */
lua_Number s = luaL_checknumber(L, 1);
lua_Number xlam = luaL_checknumber(L, 2);
lua_Number p, q, bound;
int which = 1;
int status;
check_pois(L, 1, s, xlam);
cdfpoi(&which, &p, &q, &s, &xlam, &status, &bound);
check_status(L, status, bound);
lua_pushnumber(L, p);
return 1;
}
static int cdf_qpois (lua_State *L) {
/* stack should contain p and xlam */
lua_Number p = luaL_checknumber(L, 1);
lua_Number xlam = luaL_checknumber(L, 2);
int si = 0;
check_pois(L, 2, p, xlam);
if (p==1) {
lua_pushnumber(L, HUGE_VAL);
return 1;
}
if (p>0) {
lua_Number q = 1-p;
lua_Number s, bound;
int which = 2;
int status;
cdfpoi(&which, &p, &q, &s, &xlam, &status, &bound);
check_status(status, bound);
lua_number2int(si, s);
}
lua_pushinteger(L, si);
return 1;
}