Fixed FE 1

This commit is contained in:
MBulli
2018-03-12 22:21:39 +01:00
parent c224967b19
commit 316b1d2911
11 changed files with 76 additions and 72 deletions

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@@ -10,15 +10,15 @@ Multivariate kernel functions can be constructed in various ways, however, a pop
Such a kernel is constructed by combining several univariate kernels into a product, where each kernel is applied in each dimension with a possibly different bandwidth.
Given a multivariate random variable $\bm{X}=(x_1,\dots ,x_d)$ in $d$ dimensions.
The sample set $\mathcal{X}$ is a $n\times d$ matrix \cite[162]{scott2015}.
The sample set $\mathcal{X}$ is a $n\times d$ matrix \cite{scott2015}.
The multivariate KDE $\hat{f}$ which defines the estimate pointwise at $\bm{u}=(u_1, \dots, u_d)^T$ is given as
\begin{equation}
\label{eq:mvKDE}
\hat{f}(\bm{u}) = \frac{1}{W} \sum_{i=1}^{n} \frac{w_i}{h_1 \dots h_d} \left[ \prod_{j=1}^{d} K\left( \frac{u_j-x_{ij}}{h_j} \right) \right] \text{,}
\hat{f}(\bm{u}) = \frac{1}{W} \sum_{i=1}^{n} \frac{w_i}{h_1 \dots h_d} \left[ \prod_{j=1}^{d} K\left( \frac{u_j-x_{i,j}}{h_j} \right) \right] \text{,}
\end{equation}
where the bandwidth is given as a vector $\bm{h}=(h_1, \dots, h_d)$.
Note that \eqref{eq:mvKDE} does not include all possible multivariate kernels, such as spherically symmetric kernels, which are based on rotation of a univariate kernel.
Note that \eqref{eq:mvKDE} does not include all possible multivariate kernels, such as spherically symmetric kernels, which are based on rotation of an univariate kernel.
In general, a multivariate product and spherically symmetric kernel based on the same univariate kernel will differ.
The only exception is the Gaussian kernel, which is spherically symmetric and has independent marginals. % TODO scott cite?!
In addition, only smoothing in the direction of the axes is possible.
@@ -30,7 +30,7 @@ Likewise, the ideas of common and linear binning rule scale with dimensionality
In general, multi-dimensional filters are multi-dimensional convolution operations.
However, by utilizing the separability property of convolution, a straightforward and a more efficient implementation can be found.
Convolution is separable if the filter kernel is separable, i.e. it can be split into successive convolutions of several kernels.
Convolution is separable if the filter kernel is separable, \ie{} it can be split into successive convolutions of several kernels.
In example, the Gaussian filter is separable, because of $e^{x^2+y^2} = e^{x^2}\cdot e^{y^2}$.
Likewise digital filters based on such kernels are called separable filters.
They are easily applied to multi-dimensional signals, because the input signal can be filtered in each dimension individually by an one-dimensional filter \cite{dspGuide1997}.
@@ -45,7 +45,7 @@ They are easily applied to multi-dimensional signals, because the input signal c
%These kind of multivariate kernel is called product kernel as the multivariate kernel result is the product of each individual univariate kernel.
%
%Given a multivariate random variable $X=(x_1,\dots ,x_d)$ in $d$ dimensions.
%The sample $\bm{X}$ is a $n\times d$ matrix defined as \cite[162]{scott2015}
%The sample $\bm{X}$ is a $n\times d$ matrix defined as \cite{scott2015}
%\begin{equation}
% \bm{X}=
% \begin{pmatrix}
@@ -61,7 +61,7 @@ They are easily applied to multi-dimensional signals, because the input signal c
% \end{pmatrix} \text{.}
%\end{equation}
%
%The multivariate kernel density estimator $\hat{f}$ which defines the estimate pointwise at $\bm{x}=(x_1, \dots, x_d)^T$ is given as \cite[162]{scott2015}
%The multivariate kernel density estimator $\hat{f}$ which defines the estimate pointwise at $\bm{x}=(x_1, \dots, x_d)^T$ is given as \cite{scott2015}
%\begin{equation}
% \hat{f}(\bm{x}) = \frac{1}{nh_1 \dots h_d} \sum_{i=1}^{n} \left[ \prod_{j=1}^{d} K\left( \frac{x_j-x_{ij}}{h_j} \right) \right] \text{.}
%\end{equation}
@@ -77,7 +77,7 @@ They are easily applied to multi-dimensional signals, because the input signal c
%\end{equation}
% Gaus:
%If the filter kernel is separable, the convolution is also separable i.e. multi-dimensional convolution can be computed as individual one-dimensional convolutions with a one-dimensional kernel.
%If the filter kernel is separable, the convolution is also separable \ie{} multi-dimensional convolution can be computed as individual one-dimensional convolutions with a one-dimensional kernel.
%Because of $e^{x^2+y^2} = e^{x^2}\cdot e^{y^2}$ the Gaussian filter is separable and can be easily applied to multi-dimensional signals. \todo{quelle}