almost floating point...

almost floating point...

[Jose Unpingco]

hi,

I like to use the arithmetic abilities of zsh often and have noticed
that 

z=1;
echo $(( $z + 1/3*6  ))

doesn't add 2 to 1 =3. I think the intermediate divide operation
confuses things somehow since

z=1;
echo $(( $z + 6/3  ))

does add  2+1=3.  I was wondering  what the rules for  this are? Also,
are there any  compact alternatives if one needs to  do batch floating
point computations through the shell without using PERL or AWK. For
example,

foreach file (numbers*.txt)
  < $file | <compute floating point here somehow>
end

Thank you for your time and consideration.  
----------------------------------------------------------------------
        Jose Unpingco   Mail Code ECE 0407; WK# (619) 534-5904
----------------------------------------------------------------------

Re: almost floating point...

[Duncan Sargeant]

Jose Unpingco wrote on Fri August 15, at 20:59 -0700:
> I like to use the arithmetic abilities of zsh often and have noticed
> that 
> 
> z=1;
> echo $(( $z + 1/3*6  ))
> 
> doesn't add 2 to 1 =3. I think the intermediate divide operation
> confuses things somehow since

echo $(( $z + 6*1/3 )) should do what you need.  It appears * and /
have the same precedence, and the / appears first, so 1/3 = 0 is
computed first ... ;-)

When we learnt how to use a scientific calculator in school, we were
taught "BIMDAS" (Brackets, Indices, Multiplication, Division,
Addition, Subtraction).  In Real Life integer calculation, I've never
seen a system where M & D weren't equal precedence, associating left
to right.  Ditto for A & S.

cheers
,dunc
-- 
Duncan Sargeant  -  metacitizen  -  http://www.ucc.gu.uwa.edu.au/~dunc/