From 93fc67896550548f91b307dbe3053f11db5d4a8a Mon Sep 17 00:00:00 2001 From: Steve Kargl Date: Mon, 8 Feb 2021 20:45:30 +0100 Subject: [PATCH] Fix incorrect powf(3) result with x near 1 and |y| much larger than 1 This adjusts the check to trigger overflow/underflow to a slightly lower value. Before: powf(9.999995e-01, -1.342177e+08) -> inf After: powf(9.999995e-01, -1.342177e+08) -> 1.858724e+31 MFC after: 1 week --- lib/msun/src/e_powf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/msun/src/e_powf.c b/lib/msun/src/e_powf.c index 53f1d37d6bec..33eedad50b16 100644 --- a/lib/msun/src/e_powf.c +++ b/lib/msun/src/e_powf.c @@ -136,7 +136,7 @@ __ieee754_powf(float x, float y) /* |y| is huge */ if(iy>0x4d000000) { /* if |y| > 2**27 */ /* over/underflow if x is not close to one */ - if(ix<0x3f7ffff8) return (hy<0)? sn*huge*huge:sn*tiny*tiny; + if(ix<0x3f7ffff7) return (hy<0)? sn*huge*huge:sn*tiny*tiny; if(ix>0x3f800007) return (hy>0)? sn*huge*huge:sn*tiny*tiny; /* now |1-x| is tiny <= 2**-20, suffice to compute log(x) by x-x^2/2+x^3/3-x^4/4 */