From 37eaec3ad396ea4502f4aea2395b3b5f5f69a1c6 Mon Sep 17 00:00:00 2001 From: nsz Date: Wed, 4 Apr 2012 17:34:28 +0200 Subject: [PATCH] math: fix x86 asin accuracy use (1-x)*(1+x) instead of (1-x*x) in asin.s the later can be inaccurate with upward rounding when x is close to 1 --- src/math/i386/asin.s | 5 +++-- src/math/x86_64/asinl.s | 6 +++--- 2 files changed, 6 insertions(+), 5 deletions(-) diff --git a/src/math/i386/asin.s b/src/math/i386/asin.s index cab7bfc8..932c7542 100644 --- a/src/math/i386/asin.s +++ b/src/math/i386/asin.s @@ -15,9 +15,10 @@ asinl: asin: fldl 4(%esp) 1: fld %st(0) - fmul %st(0) fld1 - fsubp %st(1) + fsub %st(0),%st(1) + fadd %st(2) + fmulp fsqrt fpatan ret diff --git a/src/math/x86_64/asinl.s b/src/math/x86_64/asinl.s index 83c392f7..ed212d9a 100644 --- a/src/math/x86_64/asinl.s +++ b/src/math/x86_64/asinl.s @@ -3,10 +3,10 @@ asinl: fldt 8(%rsp) 1: fld %st(0) - fmul %st(0) fld1 - fsubp %st(1) + fsub %st(0),%st(1) + fadd %st(2) + fmulp fsqrt fpatan ret - -- 2.25.1