[gentoo-user] Getting BC not to truncate at the decimal point?

[gentoo-user] Getting BC not to truncate at the decimal point?

[Mike Huber]

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Hi,
   I'm just trying to do some quick calculations using bc, but the version
installed through portage truncates on multiplication/division.  It didn't
used to do this 2 years ago when I was taking number theory, and there are
no USE flags available for sys-devel/bc to change this.  From the manpage:

---------------------------------------------------------------------

The most basic element in bc is the number.  Numbers are arbitrary precision
numbers.  This precision is both in the  integer  part  and  the fractional
part.  All numbers are represented internally in decimal and all computation
is done in decimal.  (This  version  truncates  results from divide and
multiply operations.)  There are two attributes of numbers, the length and
the scale.  The length is the total number of significant  decimal  digits
in a number and the scale is the total number of decimal digits after the
decimal point.  For example:
               .000001 has a length of 6 and scale of 6.
               1935.000 has a length of 7 and a scale of 3.


------------------------------------------------------------------------


Anyone have any ideas?

--Mike

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Re: [SPAM] - [gentoo-user] Getting BC not to truncate at the decimal point? - Bayesian Filter detected spam

[Harald Arnesen]

"Mike Huber" <michael.huber@gmail.com> writes:

> Hi,
>   I'm just trying to do some quick calculations using bc, but the version
> installed through portage truncates on multiplication/division.  It didn't
> used to do this 2 years ago when I was taking number theory, and there are
> no USE flags available for sys-devel/bc to change this.  From the manpage:

$ bc
bc 1.06
Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'. 
101/3
33

$ bc -l
bc 1.06
Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'. 
101/3
33.66666666666666666666
-- 
Hilsen Harald.

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Re: [SPAM] - [gentoo-user] Getting BC not to truncate at the decimal point? - Bayesian Filter detected spam

[znx]

On 24/05/06, Harald Arnesen <harald@skogtun.org> wrote:
> "Mike Huber" <michael.huber@gmail.com> writes:
>
> > Hi,
> >   I'm just trying to do some quick calculations using bc, but the version
> > installed through portage truncates on multiplication/division.  It didn't
> > used to do this 2 years ago when I was taking number theory, and there are
> > no USE flags available for sys-devel/bc to change this.  From the manpage:
>
> $ bc
> bc 1.06
> Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
> This is free software with ABSOLUTELY NO WARRANTY.
> For details type `warranty'.
> 101/3
> 33
>
> $ bc -l
> bc 1.06
> Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
> This is free software with ABSOLUTELY NO WARRANTY.
> For details type `warranty'.
> 101/3
> 33.66666666666666666666
> --
> Hilsen Harald.
>
> --
> gentoo-user@gentoo.org mailing list
>
>

Hi,

I have always understood bc has always truncated (or at least through
my general usage) whenever I have needed it to grow the decimal
precision I use the scale= option:

$ echo "101/3" | bc
33
$ echo "scale=10; 101/3" | bc
33.6666666666
$ echo "scale=3; 101/3" | bc
33.666
$ echo "101/3" | bc -l
33.66666666666666666666

-l auto sets the scale to 20 (as per manpage).  Same version of bc.

Thanks
Mark

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Re: [gentoo-user] Getting BC not to truncate at the decimal point?

[John Green]

Mike Huber wrote:

> Hi,
>    I'm just trying to do some quick calculations using bc, but the
> version installed through portage truncates on
> multiplication/division.  It didn't used to do this 2 years ago when I
> was taking number theory, and there are no USE flags available for
> sys-devel/bc to change this.  From the manpage:
>
> ---------------------------------------------------------------------
>
> The most basic element in bc is the number.  Numbers are arbitrary
> precision numbers.  This precision is both in
> the  integer  part  and  the fractional part.  All numbers are
> represented internally in decimal and all computation is done in
> decimal.  ( This  version  truncates  results from divide and multiply
> operations.)  There are two attributes of numbers, the length and the
> scale.  The length is the total number of significant  decimal  digits
> in a number and the scale is the total number of decimal digits after
> the decimal point.  For example:
>                .000001 has a length of 6 and scale of 6.
>                1935.000 has a length of 7 and a scale of 3.
>
>
> ------------------------------------------------------------------------
>
>
> Anyone have any ideas?
>
> --Mike

Hi,

Try this.

$ echo '1/5' | bc
0
$ echo '1/5' | bc -l
.20000000000000000000

I don't think bc has changed in a long time.
Maybe you forgot the -l option.

You can also control the scale explicitly like this.

echo 'scale=3;1/5' | bc -l
.200

Hope this helps.

John Green




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