From: Walton Hoops <walton@...>
Date: 2009-12-28T14:45:26+09:00
Subject: Re: Trig value errors

On 12/27/2009 10:35 PM, jzakiya wrote:
> On Dec 27, 11:50 pm, Seebs<usenet-nos...@seebs.net>  wrote:
>    
>> On 2009-12-28, jzakiya<jzak...@mail.com>  wrote:
>>
>>      
>>> All I can say is....
>>>        
>>      
>>> Against stupidity the Gods themselves contend in vain. :(
>>>        
>> This adequately summarizes the difficulty people have had getting you to
>> understand why it is ridiculous to try to "fix" sin(180) but not to try to
>> "fix" sin(45).
>>
>> -s
>> --
>> Copyright 2009, all wrongs reversed.  Peter Seebach / usenet-nos...@seebs.nethttp://www.seebs.net/log/<-- lawsuits, religion, and funny pictureshttp://en.wikipedia.org/wiki/Fair_Game_(Scientology)<-- get educated!
>>      
> No, YOU still don't seem to know the difference between
> precision an accuracy.
>
> If you can READ I said my method is no more precise, i.e
> it CANNOT resolve angular differences past the inherent
> precision of the native trig functions.
>
> But what you, and your cohorts, don't want to deal with, is my method
> IS MORE ACCURATE for sin|cos on the x|y axis angles, whereas the
> native functions are INACCURATE.
>
> So, I DON'T CARE how precise any of the other angles
> are, because they all are ACCURATE to the precision that
> the native functions have. I said this many times, and
> others have tried to explain the difference too.
>
> One thing is VERY CLEAR though.
>
> YOU, can't SHOW that my method is inaccurate for any
> angle value. Can YOU?
>
>    
Actually, he did... lets review:


On 12/27/2009 8:56 PM, John W Higgins wrote:

> First, to show that the standard methods show no greater precision lets test
> 87 degrees shall we.
>
> 1.0 - (sin(PI/180*87) ** 2 + cos(PI/180*87) ** 2)
> =>  1.11022302462516e-16
>
> So we fail with the standard and yours works
>
> 1.0 - (sin1(PI/2/90*87) ** 2 + cos1(PI/2/90*87) ** 2)
> =>  0.0
>
> But wait shall we - lets look at 67 degrees ok?
>
> 1.0 - (sin(PI/180*67) ** 2 + cos(PI/180*67) ** 2)
> =>  0.0
>
> 1.0 - (sin1(PI/180*67) ** 2 + cos1(PI/180*67) ** 2)
> =>  2.22044604925031e-16
>
> Oh no - we have a problem - your calculation fails when the standard works.


Thus, your method is inaccurate for the angle value of 67.

> Ah... A Brain is such a terrible thing to waste. :(
>
>