Date: Tue, 02 Nov 2021 05:05:52 +0000 From: bugzilla-noreply@freebsd.org To: standards@FreeBSD.org Subject: [Bug 218514] [LIBM] implementations of sinpi[fl], cospi[fl], and tanpi[fl] Message-ID: <bug-218514-99-7ADyt4r8Ra@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-218514-99@https.bugs.freebsd.org/bugzilla/> References: <bug-218514-99@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D218514 --- Comment #35 from Steve Kargl <kargl@FreeBSD.org> --- Created attachment 229215 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D229215&action= =3Dedit Final diff and this PR can be closed As mention previously, the minmax polynomial approximation in the kernel for cosl() seem to have a bad set of coefficients. In testing, cosl() in the interval [0.785, pi/4] for 1 million values and pi/4 written to 37 decimal digits. The old version on an aarch64 system gave % tlibm/tlibm_lmath -l -x 0.78 -X 7.85398163397448309615660845819875721e-1L= cos Interval tested for cosl: [0.78,0.785398] count: 1000000 xm =3D 7.80213913234863919029058821396125599e-01L libm =3D 7.10763080972549562455058499280609083e-01L mpfr =3D 7.10763080972549562455058499280608983e-01L ULP =3D 1.04431 The max ULP exceeds 1, which is not good. So, I rinsed off a 10=20 year code and recomputed coefficients. The new minmax polynomial now yields tlibm/tlibm_lmath -l -x 0.78 -X 7.85398163397448309615660845819875721e-1L = cos Interval tested for cosl: [0.78,0.785398] count: 1000000 xm =3D 7.82916198746768272588844890973704219e-01L libm =3D 7.08859615479571058183956453286628396e-01L mpfr =3D 7.08859615479571058183956453286628469e-01L ULP =3D 0.75407 which is very good. The attach fixes the coefficients. --=20 You are receiving this mail because: You are the assignee for the bug.=
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