OpenEuphoria

Re: I Need Help

• Posted by Ad Rienks <Ad_Rienks at COMPUSERVE.COM> Jun 21, 1997
• 921 views

>> There's a simple explanation for why you aren't getting the
>> results that you expect. The root of the problem is
>>that 0.1 cannot be represented in binary floating-point
>>form *exactly*. This means that if you add up ten 0.1's
>> you will *not* get 1.
>
>> Try the following statement in Euphoria:
>> ? .1 + .1 + .1 + .1 + .1 + .1 + .1 + .1 + .1 + .1 - 1
>>
>> You will not get 0. You will get -1.11e-016.
> >in other words a very very small number.

>Here is a routine that will correct such errors up to 15 decimal
>places:

>function round(atom x)
>    return floor(x*1e15+0.5)/1e15
>end function

>Maybe this will be useful to someone.

>Regards,
>               Michael Bolin

Hi Michael,

Unfortunately, this is not useful to me. If I implement it with:

fprint(1, "4.2%f", round(0.745))

what do you think I get? Well, it is 0.74! Strange enough, some of the
values x.xx5 round up in the correct way, but not all of them! Is this a
bug in my processor (P75), or in the 'binary floating point' routines?
I am puzzled over this for a long time already, as I want to do some exac=
t
financial calculating in Euphoria. Isn't this possible at all, or should =
I
maybe disable my math coprocessor?

Someone please answer me!

Ad Rienks