Hi Tim,
> Thank you Ralph for mentioning dc at the pub meet last night - really
> useful little application.
Don't let Nathan hear you. He thinks I turn every problem into one that
needs dc(1) in its solution as it is. One little use for it is
~/bin/sum to tot-up numbers.
$ cat ~/bin/sum
#! /bin/sh
(
echo 0
sed 's/$/+/' "$@"
echo p
) |
dc |
tr -d '\\\n'
echo
$
(dc splits long numbers over multiple lines, e.g. `dc
<<<'9d*d*d*d*d*d*d*d*p'' so the tr(1) splices them together again.)
Given something that gives us some random numbers,
$ gen()
> {
> tr -dc '[:digit:].\n' </dev/urandom |
> tr -s '.\n' |
> egrep -v '(^\.*$)|\..*\.'
> }
$ gen | sed 3q
8707145.3
7787948
1
$
dc gives perfect results compared with the staple `awk '{s += $0} END
{print s}'' I used to use.
$ gen | sed 10000q | sum
673447484222598337164521904782497110322692898946797077.47176958323007182340078619980536635679245283890
awk's use of floating-point has repeatedly caught me out over the years.
> There's also rpncalc in the Debian repos (HP28 emulator) which has the
> trig functions missing in dc and handles hex a bit more elegantly.
Thanks, I'll take a look.
Cheers,
Ralph.
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