[BioC] using mat.samp in siggenes

[Kathleen Kerr]

I am using the sam() function in siggenes and I 
cannot find information about using the option mat.samp:

 mat.samp: a permutation matrix. If specified, this matrix will be used,
        even if 'rand' and 'B' are specified.

I have a dataset with four treated samples and four control samples
that are paired, so my class label is:
cl=c(-1,-2,-3,-4, 1,2,3,4)

There are only 2^4=16 permutations, so I would just like to enumerate
them.  The helpfile doesn't give any information about what the
permutation matrix should look like.  

I have tried the matrix with sixteen rows, each of which
looks something like
c(-1, 2, 3,-4, 1,-2,-3,4)
but I get an error message that this is invalid.