Re: bc "remainder" operation malfunctions if scale!=0

[Erik Rossen]

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On 27 Dec 2000, Harald Anlauf wrote:

> address@hidden (Erik Rossen) writes:
> 
> > Is the following behavior normal for the remainder operation?
> > 
> > bc 1.05
> > Copyright 1991, 1992, 1993, 1994, 1997, 1998 Free Software Foundation,
> > Inc.
> > This is free software with ABSOLUTELY NO WARRANTY.
> > For details type `warranty'. 
> > scale=0
> > 5%4
> > 1
> > scale=6
> > 5%4
> > 0
> 
> RTFM!

I thought I had.

> 
>        expr % expr
>               The result of the expression is the "remainder" and
>               it is computed in the following  way.   To  compute
>               a%b,  first  a/b is computed to scale digits.  That
>               result is used to compute a-(a/b)*b to the scale of
>               the  maximum  of  scale+scale(b)  and scale(a).  If
>               scale is set to zero and both expressions are inte­
>               gers this expression is the integer remainder func­
>               tion.
> 
> Try e.g., scale=1, and then you'll see that bc is right (this time).


Ah...I get it now (after rereading 4 times).

I was looking for a modulus operator that would work for non-whole numbers
and I didn't realise that one would have to reset scale to 0 every time I
wanted % to behave this way.  When I set scale=6 in the 5%4 example above,
I was expecting 1 (short for 1.000000) as a response.

scale=0
5.5%5.4
.1
5.5%2
1.5

Yup, that's what I needed.

My apologies.  To eliminate future confusion, perhaps the last line above
could be changed to:

"The scale must be set to zero to obtain the modulus operation."

?

Erik Rossen                         ^
address@hidden                 /e\
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