[R] Simplex "Out of Bounds" Error

[Prof Brian Ripley]

On Sat, 11 Oct 2003 hstoll at latte.harvard.edu wrote:

> I am running the following code (testing the use of the simplex function to 
> determine if a point is in the convex hull of another set of points or not):
> 
> >a <- c(0, 0)
> >A3 <-matrix(c(1,2,3,4,1,1), ncol = 2, byrow = T)
> >b3 <-c(1.5, 3.5, 1)
> >simplex(a = a, A3 = A3, b3 = b3)
> 
> and the following error message appears:
>  Error in simplex1(out1$a[1:(n + m1 + m2)], out1$A[, 1:(n + m1 + m2)],  : 
>         subscript out of bounds
> 
> Any advice on why this error is appearing and how to avoid it?  (Particularly 
> the latter?)  In terms of the convex hull problem, this error seems to occur 
> when the point in question (in the convex hull or not) is on the edge/surface 
> of the convex hull.  But I'm not positive about this.  
> 
> Thanks in advance.
> 
> (I've noticed a few other posts of this problem, but never saw anyone reply.)

I assume this is function simplex() in package boot, although you did not
say so.  If so, did you contact the author (and not the maintainer) who
may well not read R-help but is the person most likely to be able to 
supply a fix?

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595