Writing new kernel option in svm E1071

Adaikalavan Ramasamy wrote:

I am trying to use the svm function in E1071 package. It does come
with built in kernel functions like radial, linear etc. I wish to use
the radial basis function but with a constant added to the diagonal of
the kernel (or Gram) matrix. This was the suggested method in a paper
UCSC-CRL-99-09 Brown et al.

So I wrote the following code, [which works correctly if I test on two
vectors manually]

kernel.new.fn <- function(u,v)
{   exp(-gamma*det(t(u-v)%*%(u-v), method="qr")) +
ifelse(identical(u, v), 0.1 ,0)    }

But when I try to run the code, I get the following error:

test.svm  <- svm( X ,  Ysvm, kernel="kernel.new.fn")

Error in svm.default(X.complete, Ysvm[, 3], kernel = "kernel.new.fn")
:
 wrong kernel specification!

I am guessing the problem being svm.default does not recognise
"kernel.new.fn".
svm.default calls a C file "svmtrain" to do the calculations.

Q1: Is there an exisiting option to add a constant to the diagonal of
the kernel ?

Q2: Is there a way I can get svm.default to recognise there is new
option called kernel.new.fn externally without meddling with C
file which I am not so familiar with.

       [OR equivalently is there a way of feeding in the
computed kernel instead - I can do this manually using a loop]

This is as much due to my lack of programming as it is to my lack of
experience with svm.

Many thanks in advance, Adai.