better power implementation
diff --git a/Objects/floatobject.c b/Objects/floatobject.c
index a2eba51..60899c9 100644
--- a/Objects/floatobject.c
+++ b/Objects/floatobject.c
@@ -316,38 +316,74 @@
return mkvalue("(dd)", div, mod);
}
+double powu(x, n)
+ double x;
+ long n;
+{
+ double r = 1.;
+ double p = x;
+ long mask = 1;
+ while (mask > 0 && n >= mask) {
+ if (n & mask)
+ r *= p;
+ mask <<= 1;
+ p *= p;
+ }
+ return r;
+}
+
+double powi(x, n)
+ double x;
+ long n;
+{
+ if (n > 10000 || n < -10000)
+ return pow(x, (double) n);
+ else if (n > 0)
+ return powu(x, n);
+ else
+ return 1./powu(x, -n);
+}
+
static object *
float_pow(v, w, z)
floatobject *v;
- floatobject *w;
+ object *w;
floatobject *z;
{
double iv, iw, ix;
- iv = v->ob_fval;
- iw = w->ob_fval;
+ long intw;
/* XXX Doesn't handle overflows if z!=None yet; it may never do so :(
* The z parameter is really only going to be useful for integers and
* long integers. Maybe something clever with logarithms could be done.
* [AMK]
*/
- /* Sort out special cases here instead of relying on pow() */
- if (iw == 0.0) { /* x**0 is 1, even 0**0 */
- if ((object *)z!=None) {
- ix=fmod(1.0, z->ob_fval);
- if (ix!=0 && z->ob_fval<0) ix+=z->ob_fval;
- }
- else ix=1.0;
- return newfloatobject(ix);
+ iv = v->ob_fval;
+ iw = ((floatobject *)w)->ob_fval;
+ intw = (long)iw;
+ if (iw == intw) {
+ errno = 0;
+ ix = powi(iv, intw);
}
- if (iv == 0.0) {
- if (iw < 0.0) {
- err_setstr(ValueError, "0.0 to a negative power");
- return NULL;
+ else {
+ /* Sort out special cases here instead of relying on pow() */
+ if (iw == 0.0) { /* x**0 is 1, even 0**0 */
+ if ((object *)z!=None) {
+ ix=fmod(1.0, z->ob_fval);
+ if (ix!=0 && z->ob_fval<0) ix+=z->ob_fval;
+ }
+ else ix=1.0;
+ return newfloatobject(ix);
}
- return newfloatobject(0.0);
+ if (iv == 0.0) {
+ if (iw < 0.0) {
+ err_setstr(ValueError, "0.0 to a negative power");
+ return NULL;
+ }
+ return newfloatobject(0.0);
+ }
+ errno = 0;
+ ix = pow(iv, iw);
}
- errno = 0;
- ix = pow(iv, iw);
CHECK(ix);
if (errno != 0) {
/* XXX could it be another type of error? */