
Hi everybody,

Thanks for checking my code, Hans, it help to see where my initial mistake was. I am sorry i assumed that there was a minimization problem. 

In short i had 2 "wavy" lines (left and right) that didn't intersect and lots of straight parallel lines that intersect the first 2 lines. I wanted to solve the intersection for the left and right line simultaneously and put everything in a big loop. And there the mistake was.

Meanwhile i was able to use Don suggestion with no problem and no loop.

Thanks again,

Monica

> Date: Thu, 1 Dec 2011 12:13:49 +0100
> Subject: Re: [R] x, y for point of intersection
> From: hwborchers@googlemail.com
> To: r-help@r-project.org
> CC: macqueen1@llnl.gov; pisicandru@hotmail.com; dwinsemius@comcast.net; ted.harding@wlandres.net
> 
> Monica has sent me some data and code for taking a quick look. As it
> turned out, there was a simple programming error on her side. The
> segm_distance() function in package 'pracma' is working correctly. And
> there is no minimization procedure in here, it simply solves some
> equations from plane geometry.
> 
> Maybe the function suggested by Don is faster, I haven't checked that.
> 
> Regards,  Hans Werner
> 
> 
> 2011/11/29 Monica Pisica <pisicandru@hotmail.com>
> >
> > Hi again,
> >
> > Working with my real data and not with the little example i sent to the list i discovered that segm_distance function from package "pracma" does not converge to 0 in all cases, even if i increase the number of iteration to 10,000 for example. It seems that it depends on the "initialization" point - most like a minimization function.
> >
> > So my thanks  go to Don who's suggestion works for the real data as well without any problems - so far ;-) He suggested to use the function crossing.psp from package "spatstat".
> >
> > Thanks again to all who have answered and helped to solve my problem. I certainly learned few new things.
> >
> > Monica
> >
> >
> >
> >
> >
> > > From: macqueen1@llnl.gov
> > > To: pisicandru@hotmail.com
> > > CC: r-help@r-project.org
> > > Date: Wed, 23 Nov 2011 14:03:42 -0800
> >
> > > Subject: Re: [R] x, y for point of intersection
> > >
> > > The function crossing.psp() in the spatstat package might be of use.
> > > Here's an excerpt from its help page:
> > >
> > > crossing.psp package:spatstat R Documentation
> > > Crossing Points of Two Line Segment PatternsDescription:
> > > Finds any crossing points between two line segment patterns.
> > > Usage:
> > > crossing.psp(A,B)
> > > -Don
> > >
> > >
> > > --
> > > Don MacQueen
> > >
> > > Lawrence Livermore National Laboratory
> > > 7000 East Ave., L-627
> > > Livermore, CA 94550
> > > 925-423-1062
> > >
> >
 		 	   		  
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