static int stat_dbinom (lua_State *L) {
/* stack should contain s, xn, pr */
lua_Number s = luaL_checknumber(L, 1);
lua_Number xn = luaL_checknumber(L, 2);
lua_Number pr = luaL_checknumber(L, 3);
check_binom(L, 1, s, xn, pr);
s = FORCE_INT(s);
xn = FORCE_INT(xn);
lua_pushnumber(L, dbinom_raw(s, xn, pr, 1 - pr));
return 1;
}
static int cdf_dbinom (lua_State *L) {
/* stack should contain s, xn, pr */
lua_Number s = luaL_checknumber(L, 1);
lua_Number xn = luaL_checknumber(L, 2);
lua_Number pr = luaL_checknumber(L, 3);
lua_Number d;
check_binom(L, 1, s, xn, pr);
xn -= s;
d = s*log(pr)+xn*log(1-pr);
xn++; s++; /* gamma correction */
d = exp(d-dlnbet(&xn, &s)-log(xn+s-1));
lua_pushnumber(L, d);
return 1;
}
static int cdf_pbinom (lua_State *L) {
/* stack should contain s, xn, pr */
lua_Number s = luaL_checknumber(L, 1);
lua_Number xn = luaL_checknumber(L, 2);
lua_Number pr = luaL_checknumber(L, 3);
lua_Number p, q, ompr, bound;
int which = 1;
int status;
check_binom(L, 1, s, xn, pr);
ompr = 1-pr;
cdfbin(&which, &p, &q, &s, &xn, &pr, &ompr, &status, &bound);
check_status(status, bound);
lua_pushnumber(L, p);
return 1;
}
static int cdf_qbinom (lua_State *L) {
/* stack should contain p, xn, pr */
lua_Number p = luaL_checknumber(L, 1);
lua_Number xn = luaL_checknumber(L, 2);
lua_Number pr = luaL_checknumber(L, 3);
lua_Number s;
int si;
check_binom(L, 2, p, xn, pr);
if (p==0 || p==1) s = p*xn;
else {
lua_Number q = 1-p;
lua_Number ompr = 1-pr;
lua_Number bound;
int which = 2;
int status;
cdfbin(&which, &p, &q, &s, &xn, &pr, &ompr, &status, &bound);
check_status(status, bound);
}
lua_number2int(si, s);
lua_pushinteger(L, si);
return 1;
}