Subject: How to deal with r^(bfloat(2/3))/r^(2.0/3)
From: zycentre
Date: Thu, 13 Dec 2007 15:29:51 +0800 (CST)
Yes, that's my fault. I used "fpprec: 5$" before, and then, just "kill(all);".
If I quit maxima first, and restart, the result is:
(%i1) bfloat(2/3)-2.0/3;
(%o1) 4.163336342344337b-17
I still want this small value to be vanished, as it will appear in an index.
When the result have one term like:
r^4.163336342344337b-17
looks not good.
So, how to set in maxima, such as: if INDEX < 1.b-16, set INDEX =0 ?
How to translate it into maxima language?
Sincerely yours,
Yuanchuan Zou
>On Dec 12, 2007 11:27 AM, zycentre <zycentre-sub at yahoo.com.cn> wrote:
>> (%i6) (bfloat(2/3))-(2.0/3);
>> (%o6) -.19073b-6
>
>In Maxima, "2.0" is a machine floating-point number, so the result in
>this case may not be exact. You might want to try
>bfloat(2/3)-(2.0b0/3).
>
>However, with default settings, the error should be < 1.0e-16, and I
>cannot reproduce your result with any settings. In fact, on my system
>(Maxima 5.13.0 on GCL 2.6.8), this returns 0.0b0.
>
>Could you please tell us the version of Maxima you are using? Does
>this happen in a fresh Maxima? If not, what special settings are you
>using?
>
> -s