harbour 3.0 ceiling(101.2/2.53)==41 bug?

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ShumingWang

Posts: 474

Joined: Sun Oct 30, 2005 06:37 AM

harbour 3.0 ceiling(101.2/2.53)==41 bug?
Posted: Wed Dec 12, 2012 09:21 AM

Hi, call Harbour 3.0 function
?ceiling(101.2/2.53)
// 41
// Should be 40.
Regards!
Shuming Wang

http://www.xtech2.top
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Email:100200651@qq.com
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Enrico Maria Giordano

Posts: 9020

Joined: Thu Oct 06, 2005 08:17 PM

Re: harbour 3.0 ceiling(101.2/2.53)==41 bug?
Posted: Wed Dec 12, 2012 09:35 AM

I get the same result using this C sample:

Code (fw): Select all Collapse

#include <stdio.h>
#include <math.h>


int main()
{
    printf( "%lf\n", ceil( 101.2 / 2.53 ) );
    return 0;
}

It's a well known problem with floating-point numbers. The result of the division is probably a little more than 40 (ie. 40.000000000001) so ceil() gives 41. You have to working around the problem using some sort of rounding.

EMG

Enrico Maria Giordano

e.m.giordano@emagsoftware.it
http://www.emagsoftware.it
http://www.emagsoftware.it/emgmusic
http://www.emagsoftware.it/spectrum
http://www.emagsoftware.it/tbosg

ShumingWang

Posts: 474

Joined: Sun Oct 30, 2005 06:37 AM

Re: harbour 3.0 ceiling(101.2/2.53)==41 bug?
Posted: Wed Dec 12, 2012 09:42 AM

EMG,
2.53X40==101.20
MySQL select ceiling(101.2/2.53)
// 40
Regards!
Shuming Wang

http://www.xtech2.top
Mobile:(86)13802729058
Email:100200651@qq.com
QQ:100200651
Weixin: qq100200651

Enrico Maria Giordano

Posts: 9020

Joined: Thu Oct 06, 2005 08:17 PM

Re: harbour 3.0 ceiling(101.2/2.53)==41 bug?
Posted: Wed Dec 12, 2012 11:30 AM

Please read something about floating-point numbers. I repeat: it's a well known problem and no, it's not specific of a particular programming language.

EMG

Enrico Maria Giordano

e.m.giordano@emagsoftware.it
http://www.emagsoftware.it
http://www.emagsoftware.it/emgmusic
http://www.emagsoftware.it/spectrum
http://www.emagsoftware.it/tbosg

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