.TH "mlpack::kernel::ExampleKernel" 3 "Tue Sep 9 2014" "Version 1.0.10" "MLPACK" \" -*- nroff -*-
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.SH NAME
mlpack::kernel::ExampleKernel \- 
.PP
An example kernel function\&.  

.SH SYNOPSIS
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.PP
.SS "Public Member Functions"

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.RI "\fBExampleKernel\fP ()"
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.RI "\fIThe default constructor, which takes no parameters\&. \fP"
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.RI "std::string \fBToString\fP () const "
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.RI "\fIReturns a string for the kernel object; in this case, with only the memory address for the kernel\&. \fP"
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.SS "Static Public Member Functions"

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.RI "template<typename VecType > static double \fBConvolutionIntegral\fP (const VecType &a, const VecType &b)"
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.RI "\fIObtains the convolution integral [integral K(||x-a||)K(||b-x||)dx] for the two vectors\&. \fP"
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.RI "template<typename VecType > static double \fBEvaluate\fP (const VecType &a, const VecType &b)"
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.RI "\fIEvaluates the kernel function for two given vectors\&. \fP"
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.RI "static double \fBNormalizer\fP ()"
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.RI "\fIObtains the normalizing volume for the kernel with dimension $dimension$\&. \fP"
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.SH "Detailed Description"
.PP 
An example kernel function\&. 

This is not a useful kernel, but it implements the two functions necessary to satisfy the Kernel policy (so that a class can be used whenever an MLPACK method calls for a \fCtypename Kernel\fP template parameter\&.
.PP
All that is necessary is a constructor and an \fC\fBEvaluate()\fP\fP function\&. More methods could be added; for instance, one useful idea is a constructor which takes parameters for a kernel (for instance, the width of the Gaussian for a Gaussian kernel)\&. However, MLPACK methods cannot count on these various constructors existing, which is why most methods allow passing an already-instantiated kernel object (and by default the method will construct the kernel with the default constructor)\&. So, for instance,
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.PP
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GaussianKernel k(5\&.0);
KDE<GaussianKernel> kde(dataset, k);
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will set up KDE using a Gaussian kernel with a width of 5\&.0, but
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KDE<GaussianKernel> kde(dataset);
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will create the kernel with the default constructor\&. It is important (but not strictly mandatory) that your default constructor still gives a working kernel\&.
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\fBNote:\fP
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Not all kernels require state\&. For instance, the regular dot product needs no parameters\&. In that case, no local variables are necessary and \fC\fBEvaluate()\fP\fP can (and should) be declared static\&. However, for greater generalization, MLPACK methods expect all kernels to require state and hence must store instantiated kernel functions; this is why a default constructor is necessary\&.  
.RE
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.PP
Definition at line 94 of file example_kernel\&.hpp\&.
.SH "Constructor & Destructor Documentation"
.PP 
.SS "mlpack::kernel::ExampleKernel::ExampleKernel ()\fC [inline]\fP"

.PP
The default constructor, which takes no parameters\&. Because our simple example kernel has no internal parameters that need to be stored, the constructor does not need to do anything\&. For a more complex example, see the \fBGaussianKernel\fP, which stores an internal parameter\&. 
.PP
Definition at line 103 of file example_kernel\&.hpp\&.
.SH "Member Function Documentation"
.PP 
.SS "template<typename VecType > static double mlpack::kernel::ExampleKernel::ConvolutionIntegral (const VecType &a, const VecType &b)\fC [inline]\fP, \fC [static]\fP"

.PP
Obtains the convolution integral [integral K(||x-a||)K(||b-x||)dx] for the two vectors\&. In this case, because our simple example kernel has no internal parameters, we can declare the function static\&. For a more complex example which cannot be declared static, see the \fBGaussianKernel\fP, which stores an internal parameter\&.
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\fBTemplate Parameters:\fP
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\fIVecType\fP Type of vector (arma::vec, arma::spvec should be expected)\&. 
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\fBParameters:\fP
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\fIa\fP First vector\&. 
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\fIb\fP Second vector\&. 
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\fBReturns:\fP
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the convolution integral value\&. 
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Definition at line 144 of file example_kernel\&.hpp\&.
.SS "template<typename VecType > static double mlpack::kernel::ExampleKernel::Evaluate (const VecType &a, const VecType &b)\fC [inline]\fP, \fC [static]\fP"

.PP
Evaluates the kernel function for two given vectors\&. In this case, because our simple example kernel has no internal parameters, we can declare the function static\&. For a more complex example which cannot be declared static, see the \fBGaussianKernel\fP, which stores an internal parameter\&.
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\fBTemplate Parameters:\fP
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\fIVecType\fP Type of vector (arma::vec, arma::spvec should be expected)\&. 
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\fBParameters:\fP
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\fIa\fP First vector\&. 
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\fIb\fP Second vector\&. 
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\fBReturns:\fP
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K(a, b)\&. 
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Definition at line 117 of file example_kernel\&.hpp\&.
.SS "static double mlpack::kernel::ExampleKernel::Normalizer ()\fC [inline]\fP, \fC [static]\fP"

.PP
Obtains the normalizing volume for the kernel with dimension $dimension$\&. In this case, because our simple example kernel has no internal parameters, we can declare the function static\&. For a more complex example which cannot be declared static, see the \fBGaussianKernel\fP, which stores an internal parameter\&.
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\fBParameters:\fP
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\fIdimension\fP the dimension of the space\&. 
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\fBReturns:\fP
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the normalization constant\&. 
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Definition at line 157 of file example_kernel\&.hpp\&.
.SS "std::string mlpack::kernel::ExampleKernel::ToString () const\fC [inline]\fP"

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Returns a string for the kernel object; in this case, with only the memory address for the kernel\&. If your kernel has any members, your \fBToString()\fP method should include those as necessary as well\&. 
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Definition at line 124 of file example_kernel\&.hpp\&.

.SH "Author"
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Generated automatically by Doxygen for MLPACK from the source code\&.