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From: Nazir Khan on 4 Aug 2010 03:28
hi der.. i am new to matlab.have used linear kernal for classification. it works fine.i want to know how can i use rbf kernal in svmtrain. please give me an example.please help!!
From: Pekka Kumpulainen on 4 Aug 2010 05:45
"Nazir Khan" <naazir_pathans(a)yahoomail.com> wrote in message <i3b4q9$hvo$1(a)fred.mathworks.com>...
> hi der.. i am new to matlab.have used linear kernal for classification. it works fine.i want to know how can i use rbf kernal in svmtrain. please give me an example.please help!!

Have you tried reading the documentation of the function you use?
Assuming you use svmtrain in Bioinformatics Toolbox,
doc svmtrain
It's all there, third in the list of Arguments
From: Nazir Khan on 6 Aug 2010 03:50
"Pekka Kumpulainen" <pekka.nospam.kumpulainen(a)tut.please.fi> wrote in message <i3bcr2$fee$1(a)fred.mathworks.com>...
> "Nazir Khan" <naazir_pathans(a)yahoomail.com> wrote in message <i3b4q9$hvo$1(a)fred.mathworks.com>...
> > hi der.. i am new to matlab.have used linear kernal for classification. it works fine.i want to know how can i use rbf kernal in svmtrain. please give me an example.please help!!
>
> Have you tried reading the documentation of the function you use?
> Assuming you use svmtrain in Bioinformatics Toolbox,
> doc svmtrain
> It's all there, third in the list of Arguments

thanku for your response Pekka Kumpulainen, i hav read the doc.. Kernel_FunctionValue corresponds to rbf, but wot is to be replaced by "kernal function"
From: Pekka Kumpulainen on 6 Aug 2010 06:32
"Nazir Khan" <naazir_pathans(a)yahoomail.com> wrote in message <i3gerg$ls6$1(a)fred.mathworks.com>...
> "Pekka Kumpulainen" <pekka.nospam.kumpulainen(a)tut.please.fi> wrote in message <i3bcr2$fee$1(a)fred.mathworks.com>...
> > "Nazir Khan" <naazir_pathans(a)yahoomail.com> wrote in message <i3b4q9$hvo$1(a)fred.mathworks.com>...
> > > hi der.. i am new to matlab.have used linear kernal for classification. it works fine.i want to know how can i use rbf kernal in svmtrain. please give me an example.please help!!
> >
> > Have you tried reading the documentation of the function you use?
> > Assuming you use svmtrain in Bioinformatics Toolbox,
> > doc svmtrain
> > It's all there, third in the list of Arguments
>
> thanku for your response Pekka Kumpulainen, i hav read the doc.. Kernel_FunctionValue corresponds to rbf, but wot is to be replaced by "kernal function"

Sorry, but now I don't quite understand what you mean with replacing something by "kernal function" (with possible typo on kernel..)

svmtrain eats ...'property',value... pairs just like many other functions
doc svmtrain: about fifth line
SVMStruct = svmtrain(..., 'Kernel_Function', Kernel_FunctionValue, ...)
and slightly down:
Kernel_FunctionValue String or function handle ....

So to use rbf kernel you specify a string 'rbf' to Kernel_FunctionValue.
and if you like to tweak the sigma in the rbf function you add that as a pair, set it to 2 for example:
SVMStruct = svmtrain(..., 'Kernel_Function', 'rbf', 'RBF_Sigma',2);

That is what it says in the doc. I haven't even used it myself (using LIBSVM instead)
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