提交 cb5c057c 编写于 作者: S Szabolcs Nagy 提交者: Rich Felker

math: fix pow(+-0,-inf) not to raise divbyzero flag

this reverts the commit f29fea00
which was based on a bug in C99 and POSIX and did not match IEEE-754
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1515.pdf
上级 1b1cafa5
......@@ -143,7 +143,7 @@ double pow(double x, double y)
return 1.0;
else if (ix >= 0x3ff00000) /* (|x|>1)**+-inf = inf,0 */
return hy >= 0 ? y : 0.0;
else if ((ix|lx) != 0) /* (|x|<1)**+-inf = 0,inf if x!=0 */
else /* (|x|<1)**+-inf = 0,inf */
return hy >= 0 ? 0.0 : -y;
}
if (iy == 0x3ff00000) { /* y is +-1 */
......
......@@ -90,7 +90,7 @@ float powf(float x, float y)
return 1.0f;
else if (ix > 0x3f800000) /* (|x|>1)**+-inf = inf,0 */
return hy >= 0 ? y : 0.0f;
else if (ix != 0) /* (|x|<1)**+-inf = 0,inf if x!=0 */
else /* (|x|<1)**+-inf = 0,inf */
return hy >= 0 ? 0.0f: -y;
}
if (iy == 0x3f800000) /* y is +-1 */
......
......@@ -227,7 +227,7 @@ long double powl(long double x, long double y)
if (y <= -LDBL_MAX) {
if (x > 1.0 || x < -1.0)
return 0.0;
if (x != 0.0)
if (x != 0.0 || y == -INFINITY)
return INFINITY;
}
if (x >= LDBL_MAX) {
......
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