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Test for negative # to the nonintegral float power here. 

Expanded powi() in-line.
This commit is contained in:
Guido van Rossum 1996-08-16 20:42:57 +00:00
parent fe58e3e22c
commit c13bcca268
1 changed files with 12 additions and 15 deletions
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27
Objects/floatobject.c
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@ -338,18 +338,6 @@ static double powu(x, n)
return r; return r;
} }
static 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 * static object *
float_pow(v, w, z) float_pow(v, w, z)
floatobject *v; floatobject *v;
@ -366,7 +354,7 @@ float_pow(v, w, z)
iv = v->ob_fval; iv = v->ob_fval;
iw = ((floatobject *)w)->ob_fval; iw = ((floatobject *)w)->ob_fval;
intw = (long)iw; intw = (long)iw;
if (iw == intw) { if (iw == intw && -10000 < intw && intw < 10000) {
/* Sort out special cases here instead of relying on pow() */ /* Sort out special cases here instead of relying on pow() */
if (intw == 0) { /* x**0 is 1, even 0**0 */ if (intw == 0) { /* x**0 is 1, even 0**0 */
if ((object *)z!=None) { if ((object *)z!=None) {
@ -377,17 +365,26 @@ float_pow(v, w, z)
return newfloatobject(ix); return newfloatobject(ix);
} }
errno = 0; errno = 0;
ix = powi(iv, intw); if (intw > 0)
ix = powu(iv, intw);
else
ix = 1./powu(iv, -intw);
} }
else { else {
/* Sort out special cases here instead of relying on pow() */ /* Sort out special cases here instead of relying on pow() */
if (iv == 0.0) { if (iv == 0.0) {
if (iw < 0.0) { if (iw < 0.0) {
err_setstr(ValueError, "0.0 to a negative power"); err_setstr(ValueError,
"0.0 to a negative power");
return NULL; return NULL;
} }
return newfloatobject(0.0); return newfloatobject(0.0);
} }
if (iv < 0.0) {
err_setstr(ValueError,
"negative number to a float power");
return NULL;
}
errno = 0; errno = 0;
ix = pow(iv, iw); ix = pow(iv, iw);
} }