OpenEuphoria

Re: atom = problem?

• Posted by Jason Gade <jaygade at yahoo?co?> Apr 28, 2008
• 824 views

Marco Achury wrote:
> 
> 
> This happens not only on Euphoria or on PC.
> In my student times, I programmed calculator CASIO FX-4000 to 
> solve hydraulic equations.  One important step is to calculate 
> friction factor for using iterative method.
> 
> Sometimes the values never converge in the same value, and mus 
> to check for a small difference instead check for equally.
> 
> Change your code to:
>  
> if abs(a - 1.8498999934219273466595723220962099730968475341796875) 
>    < 0.000001 -- Use really needed precision
> then
>  
> +-+-+-+-+-+-+-+
> Marco A. Achury
> Caracas, Venezuela

Yes, depending on the magnitude of the number, there is a smallest value,
epsilon, which can actually change that number when added or subtracted.

I had forgotten that I had written limits.e to explore some of these concepts,
with Matt's help.

You can use the functions "next_higher_atom()" and "next_lower_atom" to see if
your result falls into the proper window.

Then again, using limits.e, I would probably do it this way:

-- untested
expect = 1.849899934219273 -- better to use float64_to_atom() if you know your
exact value
result = tan(10.5)
if abs(expect - result) > get_epsilon(result) then -- fails
end if

http://www.rapideuphoria.com/limits.e

--
A complex system that works is invariably found to have evolved from a simple
system that works.
--John Gall's 15th law of Systemantics.

"Premature optimization is the root of all evil in programming."
--C.A.R. Hoare

j.