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From: Corinna Vinschen <corinna@sourceware.org>
To: newlib-cvs@sourceware.org
Subject: [newlib-cygwin] pow: fix pow(-1.0, NaN)
Date: Fri, 14 Feb 2020 09:15:00 -0000	[thread overview]
Message-ID: <20200214091542.21607.qmail@sourceware.org> (raw)

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=bb25dd1b0f39f343b764fd0db861cb9a30441407

commit bb25dd1b0f39f343b764fd0db861cb9a30441407
Author: Nicolas Brunie <nbrunie@kalray.eu>
Date:   Fri Feb 14 10:12:25 2020 +0100

    pow: fix pow(-1.0, NaN)
    
    I think I may have encountered a bug in the implementation of pow:
    pow(-1.0, NaN) returns 1.0 when it should return NaN.
    Because ix is used to check input vs 1.0 rather than hx, -1.0 is
    mistaken for 1.0

Diff:
---
 newlib/libm/math/e_pow.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/newlib/libm/math/e_pow.c b/newlib/libm/math/e_pow.c
index 6d2a501..5fd28e6 100644
--- a/newlib/libm/math/e_pow.c
+++ b/newlib/libm/math/e_pow.c
@@ -122,7 +122,7 @@ ivln2_l  =  1.92596299112661746887e-08; /* 0x3E54AE0B, 0xF85DDF44 =1/ln2 tail*/
     /* x|y==NaN return NaN unless x==1 then return 1 */
 	if(ix > 0x7ff00000 || ((ix==0x7ff00000)&&(lx!=0)) ||
 	   iy > 0x7ff00000 || ((iy==0x7ff00000)&&(ly!=0))) {
-	    if(((ix-0x3ff00000)|lx)==0) return one;
+	    if(((hx-0x3ff00000)|lx)==0) return one;
 	    else return nan("");	
 	}


                 reply	other threads:[~2020-02-14  9:15 UTC|newest]

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