From: Damian McGuckin <damianm@esi.com.au>
To: musl@lists.openwall.com
Subject: Re: [musl] casinh function accuracy problem
Date: Wed, 12 Feb 2020 15:07:17 +1100 (AEDT) [thread overview]
Message-ID: <alpine.LRH.2.02.2002121450170.16988@key0.esi.com.au> (raw)
In-Reply-To: <20200212020023.GV1663@brightrain.aerifal.cx>
On Tue, 11 Feb 2020, Rich Felker wrote:
> My minimal criterion for large-scale improvements of src/complex would
> be fixing any remaining cases where inf/nan behavior is badly wrong or
> there's catastrophic error (>2^52 ulp, or even just >2^20 ulp or so).
> Beyond that, I think "reducing ulp error" would be nice but hard to
> quantify and make a goal without having an idea how bad it is now, not
> to mention without having rigorous error bounds on the real math
> library functions.
I think INF/NaN behaviour at the fundamental level is flawed.
This initialization:
double complex x = 1.0e+200 + INFINITY * I;
on every compiler I try, yields an 'x' of
NaN + INFINITY i
Whereas if I compute
double complex a = 2.0 + 1.0e200 * I;
double complex b = 1.0e200 + 1.0 * I;
double x = a * b;
then 'x' prints correctly as
1.0e+200 + INF * I;
Regards - Damian
Pacific Engineering Systems International, 277-279 Broadway, Glebe NSW 2037
Ph:+61-2-8571-0847 .. Fx:+61-2-9692-9623 | unsolicited email not wanted here
Views & opinions here are mine and not those of any past or present employer
next prev parent reply other threads:[~2020-02-12 4:07 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-11 15:51 mg1633068
2020-02-11 19:30 ` Szabolcs Nagy
2020-02-11 23:24 ` Rich Felker
2020-02-12 0:46 ` Damian McGuckin
2020-02-12 2:00 ` Rich Felker
2020-02-12 4:07 ` Damian McGuckin [this message]
2020-02-12 4:19 ` Rich Felker
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