[Haskell-cafe] Rotating calipers
mukesh tiwari
mukeshtiwari.iiitm at gmail.com
Mon Aug 8 01:01:12 CEST 2011
Thank you Tillmann Vogt. I really appreciate your help . Finally
implemented working code [ http://hpaste.org/49957 ] .
Thank you
Mukesh Tiwari
On Aug 7, 3:16 pm, Tillmann Vogt <Tillmann.V... at rwth-aachen.de> wrote:
> Am 06.08.2011 22:23, schrieb mukesh tiwari:
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> >> There are several algorithms mentioned on that page. Do you need the
> >> diameter, width, or something else?
> > Oh , I did not realize that .Actually first i implemented diameter
> > algorithm [http://hpaste.org/49925] and tested it on couple of test
> > cases . Its working fine then i tried to implement " The minimum area
> > enclosing rectangle for a convex polygon" using four calipers but i
> > don't know whats wrong code.
> >> Do you have some example data and what wrong result you get?
> > For any test input [ which i tried ] it outputs 4 . If its implemented
> > correctly then it will accepted here with slight modification [
> >http://www.spoj.pl/problems/WLOO0707] since it asks for square area.
> > Couple of test cases which i tried .
>
> > ghci>final [ P 1 1 , P 2 2 , P 0 100 , P 0 1 ]
> > Loading package array-0.3.0.0 ... linking ... done.
> > Loading package bytestring-0.9.1.5 ... linking ... done.
> > 4.0
>
> > ghci>final [ P 0 0 ,P 5 1 , P 9 2 , P 12 3 , P 14 4 , P 15 5 , P 16
> > 7 , P 17 10 , P 18 14 , P 19 19 ]
> > 3.9999999999999982
>
> > ghci>final [ P 2 ( -3 ) , P (-1 ) 2 , P 0 5 , P (-5) (-1) , P (-4)
> > ( 2 ) , P 4 0 , P 1 3 , P 4 3 , P (-3) (-4) , P 0 (-2)]
> > 4.0
>
> > Thank you
> > Mukesh Tiwari
>
> I found the error!
>
> In
> > width = distVec cpa' cpb'
> > length = distVec cqa' cqb'
> the length of the direction vectors is used to compute the area and the
> area is then always 4.
>
> Replace it with
> > width = distVec (V x1 y1) (V x3 y3)
> > length = distVec (V x5 y5) (V x7 y7)
>
> and it seems to work:
>
> ghci> final [ P 1 1 , P 2 2 , P 0 100 , P 0 1 ]
> 221.3707297724792
>
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