[Israel.pm] Another perl vs ruby

ynon perek ynonperek at gmail.com
Sat Mar 31 02:44:13 PDT 2012


Hi,
Thanks for the tip - I actually started with: use bigrat, but removed it
because it made everything really slow - about 10 times slower than without
(plus program still worked without on my test cases).

Any ideas for modules that will do the same (only faster) ?

On 28 March 2012 23:52, Shlomi Fish <shlomif at shlomifish.org> wrote:

> Hi Ynon,
>
> On Wed, 28 Mar 2012 10:55:44 +0200
> ynon perek <ynonperek at gmail.com> wrote:
>
> > Hi All,
> >
> > A student asked me for a perl solution to the problem at the bottom.
> >
> [SNIPPED]
> >
> > Write a program that takes a list of numbers, a list of operators, and a
> > goal; and tells the user which mathematical operations must be performed
> to
> > reach the goal. For example, given the input:
> > numbers: 2, 4, 6, 8
> > operators: +, -, *, /
> > goal: 25
> >
> > Program should produce the output:
> > sol = (((2 / 8) + 6) * 4)
> > ----
>
> Just a note - I hope here would be OK. You should use a rational numbers
> package (a.k.a "fractions" - see for example
> https://metacpan.org/module/Math::BigRat or
> https://metacpan.org/module/Math::GMPq )
> instead of relying on floating-point numbers for solving such riddles,
> because
> otherwise, you might have some rounding errors. I recall facing a problem,
> where I was trying to write a Perl program to brute force such a riddle
> which
> I had some problems with, and it did not yield the exact solution due to
> this
> issue.
>
> For more inforamation about why this is an issue, see:
>
> http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html
>
> «What Every Computer Scientist Should Know About Floating-Point Arithmetic»
>
> Regards,
>
>        Shlomi Fish
>
> --
> -----------------------------------------------------------------
> Shlomi Fish       http://www.shlomifish.org/
> What does "Zionism" mean? - http://shlom.in/def-zionism
>
> If his programming is anything like his philosophising, he would find ten
> imaginary bugs in the “Hello World” program.
>
> Please reply to list if it's a mailing list post - http://shlom.in/reply .
>
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