Re: [bug-gawk] sin() and cos() return wrong results

[winn]

Hi,


I checked angain and saw the results are correct. Last time I got incorrect 
calculation results so I traced the process and saw it happened at sin() and 
cosine() functions. I didn't keep a screenshot.


My system is Windows 10 x64, and I used gawk in Cygwin.


Sorry for the trouble, and thank you all for your kind help.


Charles






------------------ Original ------------------
From:  "Andrew J. Schorr"<address@hidden>;
Date:  Thu, Oct 18, 2018 10:40 PM
To:  "winn"<address@hidden>;
Cc:  "bug-gawk"<address@hidden>; 
Subject:  Re: [bug-gawk] sin() and cos() return wrong results



Hi,

On Thu, Oct 18, 2018 at 04:53:11PM +0800, winn wrote:
> I found both sin() and cos() return wrong results in gawk-3.1.8 and 
> gawk-4.1.3.
> 
> 
> I compared the results with that in Excel, Windows calculator, and Python, 
> and confirmed this error.
> 
> 
> Please have a check.

Can you please provide some examples of calculations that you think are
incorrect? At first glance, it seems to work OK:

bash-4.2$ gawk 'BEGIN {pi = atan2(0, -1); print cos(0), sin(0), cos(pi/2), 
sin(pi/2)}'
1 0 6.12323e-17 1

This matches the results in Python 3.7:

bash-4.2$ python3 -c "from math import *; pi = atan2(0,-1); print(cos(0), 
sin(0), cos(pi/2), sin(pi/2))"
1.0 0.0 6.123233995736766e-17 1.0

Regards,
Andy