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From: "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu>
Newsgroups: comp.lang.fortran
Subject: Re: Angle Units For Trig Functions
Date: Thu, 24 Oct 2024 05:06:37 -0000 (UTC)
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On Thu, 24 Oct 2024 04:47:06 +0000, Lawrence D'Oliveiro wrote:

> On Thu, 24 Oct 2024 02:17:15 -0000 (UTC), Steven G. Kargl wrote:
> 
>> One of these values is wrong.
> 
> Only if you assume the input numbers were somehow “exact” or “perfect” to 
> begin with.
> 
> There’s an old principle in computing: “Garbage In, Garbage Out”.

People discussing Fortran normally use floating point math when
computing sin(x) or any other function of a "real" quantity.

> 
>> You seem to be missing that argument reduction for sind(x)
>> is much easier than argument reduction for sin(x).
> 
> But that only worked for one angle, and for nothing else.

ROFL.

For sin(x), argument reduction will give sin(0) = 0, exactly.
That's one angle.

For sind(x), argument reduction will give sind(x) = 0, exactly,
for countable many angles.

-- 
steve