From: Walton Hoops <walton@...>
Date: 2009-12-28T15:26:45+09:00
Subject: Re: Trig value errors

On 12/27/2009 11:04 PM, jzakiya wrote:
> My methods
>    
>> sin1(67*degrees) =>  0.92050485345244
>> cos1(67*degrees) =>  0.39073112848927
>>      
> Ruby methods
>
>    
>> sin(67*degrees) =>  0.92050485345244
>> cos(67*degrees) =>  0.39073112848927
>>      
> Same answers.
>
>    
Really? huh....

irb(main):017:0> def sin1(x)
irb(main):018:1>   y=(1-cos(x)**2)**0.5        # calculate (2)
irb(main):019:1>   return 0.0 if y==0
irb(main):020:1>   return sin(x) < 0 ? -y : y  # for correct quadrant sign
irb(main):021:1> end
=> nil
irb(main):022:0> def cos1(x)
irb(main):023:1>   y=(1-sin(x)**2)**0.5        # calculate (2)
irb(main):024:1>   return 0.0 if y==0
irb(main):025:1>   return cos(x) < 0 ? -y : y  # for correct quadrant sign
irb(main):026:1> end
=> nil
irb(main):027:0> degrees=PI/180
=> 0.0174532925199433
irb(main):028:0> s0=sin1(67*degrees)
=> 0.92050485345244
irb(main):029:0> c0=cos1(67*degrees)
=> 0.390731128489274
irb(main):030:0> s1=sin(67*degrees)
=> 0.92050485345244
irb(main):031:0> c1=cos(67*degrees)
=> 0.390731128489274
irb(main):032:0> s0==s1
=> false
irb(main):033:0> c0==c1
=> false
irb(main):034:0> s0-s1
=> -1.11022302462516e-16
irb(main):035:0> c0-c1
=> -5.55111512312578e-17
irb(main):036:0>


whoops.. guess they aren't equal after all.

Similarly, from one of your earlier examples:

irb(main):036:0> s=sin((360-1e-6)*degrees)
=> -1.74532923897938e-08
irb(main):037:0> c=cos((360-1e-6)*degrees)
=> 1.0
irb(main):038:0> c==1
=> false
irb(main):039:0> 1-c
=> 1.11022302462516e-16

That 1 isn't really a 1.  This has been pointed out before, you just 
chose to ignore it.


> It's clear you jokers just like to argue and spew nonsense. You make
> stupid statements and provide no
> data to establish your claims. But I guess well thought
> out and consistent reproducible claims are just too
> much for you guys to produce.
>
> Are you guys Republicans and/or Global Climate Change deniers too?
>
>