static VALUE
BigDecimal_power(int argc, VALUE*argv, VALUE self)
{
ENTER(5);
VALUE vexp, prec;
Real* exp = NULL;
Real *x, *y;
ssize_t mp, ma, n;
SIGNED_VALUE int_exp;
double d;
rb_scan_args(argc, argv, "11", &vexp, &prec);
GUARD_OBJ(x, GetVpValue(self, 1));
n = NIL_P(prec) ? (ssize_t)(x->Prec*VpBaseFig()) : NUM2SSIZET(prec);
if (VpIsNaN(x)) {
y = VpCreateRbObject(n, "0#");
RB_GC_GUARD(y->obj);
VpSetNaN(y);
return ToValue(y);
}
retry:
switch (TYPE(vexp)) {
case T_FIXNUM:
break;
case T_BIGNUM:
break;
case T_FLOAT:
d = RFLOAT_VALUE(vexp);
if (d == round(d)) {
if (FIXABLE(d)) {
vexp = LONG2FIX((long)d);
}
else {
vexp = rb_dbl2big(d);
}
goto retry;
}
exp = GetVpValueWithPrec(vexp, DBL_DIG+1, 1);
break;
case T_RATIONAL:
if (is_zero(rb_rational_num(vexp))) {
if (is_positive(vexp)) {
vexp = INT2FIX(0);
goto retry;
}
}
else if (is_one(rb_rational_den(vexp))) {
vexp = rb_rational_num(vexp);
goto retry;
}
exp = GetVpValueWithPrec(vexp, n, 1);
break;
case T_DATA:
if (is_kind_of_BigDecimal(vexp)) {
VALUE zero = INT2FIX(0);
VALUE rounded = BigDecimal_round(1, &zero, vexp);
if (RTEST(BigDecimal_eq(vexp, rounded))) {
vexp = BigDecimal_to_i(vexp);
goto retry;
}
exp = DATA_PTR(vexp);
break;
}
/* fall through */
default:
rb_raise(rb_eTypeError,
"wrong argument type %"PRIsVALUE" (expected scalar Numeric)",
RB_OBJ_CLASSNAME(vexp));
}
if (VpIsZero(x)) {
if (is_negative(vexp)) {
y = VpCreateRbObject(n, "#0");
RB_GC_GUARD(y->obj);
if (BIGDECIMAL_NEGATIVE_P(x)) {
if (is_integer(vexp)) {
if (is_even(vexp)) {
/* (-0) ** (-even_integer) -> Infinity */
VpSetPosInf(y);
}
else {
/* (-0) ** (-odd_integer) -> -Infinity */
VpSetNegInf(y);
}
}
else {
/* (-0) ** (-non_integer) -> Infinity */
VpSetPosInf(y);
}
}
else {
/* (+0) ** (-num) -> Infinity */
VpSetPosInf(y);
}
return ToValue(y);
}
else if (is_zero(vexp)) {
return ToValue(VpCreateRbObject(n, "1"));
}
else {
return ToValue(VpCreateRbObject(n, "0"));
}
}
if (is_zero(vexp)) {
return ToValue(VpCreateRbObject(n, "1"));
}
else if (is_one(vexp)) {
return self;
}
if (VpIsInf(x)) {
if (is_negative(vexp)) {
if (BIGDECIMAL_NEGATIVE_P(x)) {
if (is_integer(vexp)) {
if (is_even(vexp)) {
/* (-Infinity) ** (-even_integer) -> +0 */
return ToValue(VpCreateRbObject(n, "0"));
}
else {
/* (-Infinity) ** (-odd_integer) -> -0 */
return ToValue(VpCreateRbObject(n, "-0"));
}
}
else {
/* (-Infinity) ** (-non_integer) -> -0 */
return ToValue(VpCreateRbObject(n, "-0"));
}
}
else {
return ToValue(VpCreateRbObject(n, "0"));
}
}
else {
y = VpCreateRbObject(n, "0#");
if (BIGDECIMAL_NEGATIVE_P(x)) {
if (is_integer(vexp)) {
if (is_even(vexp)) {
VpSetPosInf(y);
}
else {
VpSetNegInf(y);
}
}
else {
/* TODO: support complex */
rb_raise(rb_eMathDomainError,
"a non-integral exponent for a negative base");
}
}
else {
VpSetPosInf(y);
}
return ToValue(y);
}
}
if (exp != NULL) {
return rmpd_power_by_big_decimal(x, exp, n);
}
else if (RB_TYPE_P(vexp, T_BIGNUM)) {
VALUE abs_value = BigDecimal_abs(self);
if (is_one(abs_value)) {
return ToValue(VpCreateRbObject(n, "1"));
}
else if (RTEST(rb_funcall(abs_value, '<', 1, INT2FIX(1)))) {
if (is_negative(vexp)) {
y = VpCreateRbObject(n, "0#");
if (is_even(vexp)) {
VpSetInf(y, VpGetSign(x));
}
else {
VpSetInf(y, -VpGetSign(x));
}
return ToValue(y);
}
else if (BIGDECIMAL_NEGATIVE_P(x) && is_even(vexp)) {
return ToValue(VpCreateRbObject(n, "-0"));
}
else {
return ToValue(VpCreateRbObject(n, "0"));
}
}
else {
if (is_positive(vexp)) {
y = VpCreateRbObject(n, "0#");
if (is_even(vexp)) {
VpSetInf(y, VpGetSign(x));
}
else {
VpSetInf(y, -VpGetSign(x));
}
return ToValue(y);
}
else if (BIGDECIMAL_NEGATIVE_P(x) && is_even(vexp)) {
return ToValue(VpCreateRbObject(n, "-0"));
}
else {
return ToValue(VpCreateRbObject(n, "0"));
}
}
}
int_exp = FIX2LONG(vexp);
ma = int_exp;
if (ma < 0) ma = -ma;
if (ma == 0) ma = 1;
if (VpIsDef(x)) {
mp = x->Prec * (VpBaseFig() + 1);
GUARD_OBJ(y, VpCreateRbObject(mp * (ma + 1), "0"));
}
else {
GUARD_OBJ(y, VpCreateRbObject(1, "0"));
}
VpPower(y, x, int_exp);
if (!NIL_P(prec) && VpIsDef(y)) {
VpMidRound(y, VpGetRoundMode(), n);
}
return ToValue(y);
}