root/doc/latex/classbdm_1_1EKFCh.tex @ 271

Revision 271, 16.2 kB (checked in by smidl, 16 years ago)

Next major revision

Line 
1\hypertarget{classbdm_1_1EKFCh}{
2\section{bdm::EKFCh Class Reference}
3\label{classbdm_1_1EKFCh}\index{bdm::EKFCh@{bdm::EKFCh}}
4}
5{\tt \#include $<$libKF.h$>$}
6
7Inheritance diagram for bdm::EKFCh::\begin{figure}[H]
8\begin{center}
9\leavevmode
10\includegraphics[height=6cm]{classbdm_1_1EKFCh}
11\end{center}
12\end{figure}
13
14
15\subsection{Detailed Description}
16Extended \hyperlink{classbdm_1_1Kalman}{Kalman} Filter in Square root.
17
18An approximation of the exact Bayesian filter with Gaussian noices and non-linear evolutions of their mean. \subsection*{Public Member Functions}
19\begin{CompactItemize}
20\item 
21\hypertarget{classbdm_1_1EKFCh_8b3228a594532b6a0db0fdc065bc5b9f}{
22\hyperlink{classbdm_1_1EKFCh_8b3228a594532b6a0db0fdc065bc5b9f}{EKFCh} ()}
23\label{classbdm_1_1EKFCh_8b3228a594532b6a0db0fdc065bc5b9f}
24
25\begin{CompactList}\small\item\em Default constructor. \item\end{CompactList}\item 
26\hypertarget{classbdm_1_1EKFCh_50f9fbffad721f35e5ccb75d0f6b842a}{
27void \hyperlink{classbdm_1_1EKFCh_50f9fbffad721f35e5ccb75d0f6b842a}{set\_\-parameters} (\hyperlink{classbdm_1_1diffbifn}{diffbifn} $\ast$\hyperlink{classbdm_1_1EKFCh_e1e895f994398a55bc425551fc275ba3}{pfxu}, \hyperlink{classbdm_1_1diffbifn}{diffbifn} $\ast$\hyperlink{classbdm_1_1EKFCh_6b34c69641826322467b704e8252f317}{phxu}, const \hyperlink{classchmat}{chmat} Q0, const \hyperlink{classchmat}{chmat} R0)}
28\label{classbdm_1_1EKFCh_50f9fbffad721f35e5ccb75d0f6b842a}
29
30\begin{CompactList}\small\item\em Set nonlinear functions for mean values and covariance matrices. \item\end{CompactList}\item 
31\hypertarget{classbdm_1_1EKFCh_4c8609c37290b158f88a31dae4047225}{
32void \hyperlink{classbdm_1_1EKFCh_4c8609c37290b158f88a31dae4047225}{bayes} (const vec \&dt)}
33\label{classbdm_1_1EKFCh_4c8609c37290b158f88a31dae4047225}
34
35\begin{CompactList}\small\item\em Here dt = \mbox{[}yt;ut\mbox{]} of appropriate dimensions. \item\end{CompactList}\item 
36\hypertarget{classbdm_1_1KalmanCh_20a4d4c664e8ac8a3f1bb7b0d11c6d87}{
37void \hyperlink{classbdm_1_1KalmanCh_20a4d4c664e8ac8a3f1bb7b0d11c6d87}{set\_\-parameters} (const mat \&A0, const mat \&B0, const mat \&C0, const mat \&D0, const \hyperlink{classchmat}{chmat} \&Q0, const \hyperlink{classchmat}{chmat} \&R0)}
38\label{classbdm_1_1KalmanCh_20a4d4c664e8ac8a3f1bb7b0d11c6d87}
39
40\begin{CompactList}\small\item\em Set parameters with check of relevance. \item\end{CompactList}\item 
41\hypertarget{classbdm_1_1KalmanCh_6e169272657ed101f3d128b49c59b890}{
42void \textbf{set\_\-statistics} (const vec \&mu0, const \hyperlink{classchmat}{chmat} \&P0)}
43\label{classbdm_1_1KalmanCh_6e169272657ed101f3d128b49c59b890}
44
45\item 
46\hypertarget{classbdm_1_1Kalman_9264fc6b173ecb803d2684b883f32c68}{
47void \hyperlink{classbdm_1_1Kalman_9264fc6b173ecb803d2684b883f32c68}{set\_\-est} (const vec \&mu0, const \hyperlink{classchmat}{chmat} \&P0)}
48\label{classbdm_1_1Kalman_9264fc6b173ecb803d2684b883f32c68}
49
50\begin{CompactList}\small\item\em Set estimate values, used e.g. in initialization. \item\end{CompactList}\item 
51\hypertarget{classbdm_1_1Kalman_f75e487ff6c129d7012d702030f8c890}{
52const \hyperlink{classbdm_1_1epdf}{epdf} \& \hyperlink{classbdm_1_1Kalman_f75e487ff6c129d7012d702030f8c890}{posterior} () const }
53\label{classbdm_1_1Kalman_f75e487ff6c129d7012d702030f8c890}
54
55\begin{CompactList}\small\item\em access function \item\end{CompactList}\item 
56\hypertarget{classbdm_1_1Kalman_c34989b1e53c7d4ecdaea63a95ddbd77}{
57const \hyperlink{classbdm_1_1enorm}{enorm}$<$ \hyperlink{classchmat}{chmat} $>$ $\ast$ \textbf{\_\-e} () const }
58\label{classbdm_1_1Kalman_c34989b1e53c7d4ecdaea63a95ddbd77}
59
60\item 
61\hypertarget{classbdm_1_1Kalman_c788ec6e6c6f5f5861ae8a56d8ede277}{
62mat \& \hyperlink{classbdm_1_1Kalman_c788ec6e6c6f5f5861ae8a56d8ede277}{\_\-\_\-K} ()}
63\label{classbdm_1_1Kalman_c788ec6e6c6f5f5861ae8a56d8ede277}
64
65\begin{CompactList}\small\item\em access function \item\end{CompactList}\item 
66\hypertarget{classbdm_1_1Kalman_a250d1dbe7bba861dba2a324520cfa48}{
67vec \hyperlink{classbdm_1_1Kalman_a250d1dbe7bba861dba2a324520cfa48}{\_\-dP} ()}
68\label{classbdm_1_1Kalman_a250d1dbe7bba861dba2a324520cfa48}
69
70\begin{CompactList}\small\item\em access function \item\end{CompactList}\end{CompactItemize}
71\begin{Indent}{\bf Constructors}\par
72\begin{CompactItemize}
73\item 
74virtual \hyperlink{classbdm_1_1BM}{BM} $\ast$ \hyperlink{classbdm_1_1BM_c0f027ff91d8459937c6f60ff8e553ff}{\_\-copy\_\-} ()
75\end{CompactItemize}
76\end{Indent}
77\begin{Indent}{\bf Mathematical operations}\par
78\begin{CompactItemize}
79\item 
80\hypertarget{classbdm_1_1BM_1dee3fddaf021e62d925289660a707dc}{
81virtual void \hyperlink{classbdm_1_1BM_1dee3fddaf021e62d925289660a707dc}{bayesB} (const mat \&Dt)}
82\label{classbdm_1_1BM_1dee3fddaf021e62d925289660a707dc}
83
84\begin{CompactList}\small\item\em Batch Bayes rule (columns of Dt are observations). \item\end{CompactList}\item 
85virtual double \hyperlink{classbdm_1_1BM_50257e0c1e5b5c73153ea6e716ad8ae0}{logpred} (const vec \&dt) const
86\item 
87\hypertarget{classbdm_1_1BM_0e8ebe61fb14990abe1254bd3dda5fae}{
88vec \hyperlink{classbdm_1_1BM_0e8ebe61fb14990abe1254bd3dda5fae}{logpred\_\-m} (const mat \&dt) const }
89\label{classbdm_1_1BM_0e8ebe61fb14990abe1254bd3dda5fae}
90
91\begin{CompactList}\small\item\em Matrix version of logpred. \item\end{CompactList}\item 
92\hypertarget{classbdm_1_1BM_688d7a2aced1e06aa1c468d73a9e5eba}{
93virtual \hyperlink{classbdm_1_1epdf}{epdf} $\ast$ \hyperlink{classbdm_1_1BM_688d7a2aced1e06aa1c468d73a9e5eba}{epredictor} () const }
94\label{classbdm_1_1BM_688d7a2aced1e06aa1c468d73a9e5eba}
95
96\begin{CompactList}\small\item\em Constructs a predictive density $ f(d_{t+1} |d_{t}, \ldots d_{0}) $. \item\end{CompactList}\item 
97\hypertarget{classbdm_1_1BM_598b25e3f3d96a5bc00a5faeb5b3c912}{
98virtual \hyperlink{classbdm_1_1mpdf}{mpdf} $\ast$ \hyperlink{classbdm_1_1BM_598b25e3f3d96a5bc00a5faeb5b3c912}{predictor} () const }
99\label{classbdm_1_1BM_598b25e3f3d96a5bc00a5faeb5b3c912}
100
101\begin{CompactList}\small\item\em Constructs a conditional density 1-step ahead predictor. \item\end{CompactList}\end{CompactItemize}
102\end{Indent}
103\begin{Indent}{\bf Access to attributes}\par
104\begin{CompactItemize}
105\item 
106\hypertarget{classbdm_1_1BM_ff2d8755ba0b3def927d31305c03b09c}{
107const \hyperlink{classbdm_1_1RV}{RV} \& \textbf{\_\-drv} () const }
108\label{classbdm_1_1BM_ff2d8755ba0b3def927d31305c03b09c}
109
110\item 
111\hypertarget{classbdm_1_1BM_f135ae6dce7e9f30c9f88229c7930b96}{
112void \textbf{set\_\-drv} (const \hyperlink{classbdm_1_1RV}{RV} \&rv)}
113\label{classbdm_1_1BM_f135ae6dce7e9f30c9f88229c7930b96}
114
115\item 
116\hypertarget{classbdm_1_1BM_b38d92f17620813ad872d86e01a26e5e}{
117void \textbf{set\_\-rv} (const \hyperlink{classbdm_1_1RV}{RV} \&rv)}
118\label{classbdm_1_1BM_b38d92f17620813ad872d86e01a26e5e}
119
120\item 
121\hypertarget{classbdm_1_1BM_5be65d37dedfe33a3671e7065f523a70}{
122double \textbf{\_\-ll} () const }
123\label{classbdm_1_1BM_5be65d37dedfe33a3671e7065f523a70}
124
125\item 
126\hypertarget{classbdm_1_1BM_236b3abbcc93594fc97cd86d82c1a83f}{
127void \textbf{set\_\-evalll} (bool evl0)}
128\label{classbdm_1_1BM_236b3abbcc93594fc97cd86d82c1a83f}
129
130\end{CompactItemize}
131\end{Indent}
132\subsection*{Protected Attributes}
133\begin{CompactItemize}
134\item 
135\hypertarget{classbdm_1_1EKFCh_e1e895f994398a55bc425551fc275ba3}{
136\hyperlink{classbdm_1_1diffbifn}{diffbifn} $\ast$ \hyperlink{classbdm_1_1EKFCh_e1e895f994398a55bc425551fc275ba3}{pfxu}}
137\label{classbdm_1_1EKFCh_e1e895f994398a55bc425551fc275ba3}
138
139\begin{CompactList}\small\item\em Internal Model f(x,u). \item\end{CompactList}\item 
140\hypertarget{classbdm_1_1EKFCh_6b34c69641826322467b704e8252f317}{
141\hyperlink{classbdm_1_1diffbifn}{diffbifn} $\ast$ \hyperlink{classbdm_1_1EKFCh_6b34c69641826322467b704e8252f317}{phxu}}
142\label{classbdm_1_1EKFCh_6b34c69641826322467b704e8252f317}
143
144\begin{CompactList}\small\item\em Observation Model h(x,u). \item\end{CompactList}\item 
145\hypertarget{classbdm_1_1KalmanCh_48611c8582706cfa62e832be0972e75d}{
146mat \hyperlink{classbdm_1_1KalmanCh_48611c8582706cfa62e832be0972e75d}{preA}}
147\label{classbdm_1_1KalmanCh_48611c8582706cfa62e832be0972e75d}
148
149\begin{CompactList}\small\item\em pre array (triangular matrix) \item\end{CompactList}\item 
150\hypertarget{classbdm_1_1KalmanCh_bcbd68f51d4b57246e7784ca5900171f}{
151mat \hyperlink{classbdm_1_1KalmanCh_bcbd68f51d4b57246e7784ca5900171f}{postA}}
152\label{classbdm_1_1KalmanCh_bcbd68f51d4b57246e7784ca5900171f}
153
154\begin{CompactList}\small\item\em post array (triangular matrix) \item\end{CompactList}\item 
155\hypertarget{classbdm_1_1Kalman_3fe475a1e920b20b63bb342c0e1571f7}{
156\hyperlink{classbdm_1_1RV}{RV} \hyperlink{classbdm_1_1Kalman_3fe475a1e920b20b63bb342c0e1571f7}{rvy}}
157\label{classbdm_1_1Kalman_3fe475a1e920b20b63bb342c0e1571f7}
158
159\begin{CompactList}\small\item\em Indetifier of output rv. \item\end{CompactList}\item 
160\hypertarget{classbdm_1_1Kalman_149e27424fd1a7cc1c998ea088618a94}{
161\hyperlink{classbdm_1_1RV}{RV} \hyperlink{classbdm_1_1Kalman_149e27424fd1a7cc1c998ea088618a94}{rvu}}
162\label{classbdm_1_1Kalman_149e27424fd1a7cc1c998ea088618a94}
163
164\begin{CompactList}\small\item\em Indetifier of exogeneous rv. \item\end{CompactList}\item 
165\hypertarget{classbdm_1_1Kalman_ba7699cdb3b1382a54d3e28b9b7517fa}{
166int \hyperlink{classbdm_1_1Kalman_ba7699cdb3b1382a54d3e28b9b7517fa}{dimx}}
167\label{classbdm_1_1Kalman_ba7699cdb3b1382a54d3e28b9b7517fa}
168
169\begin{CompactList}\small\item\em cache of rv.count() \item\end{CompactList}\item 
170\hypertarget{classbdm_1_1Kalman_d2c36ba01760bf207b985bf321b7817f}{
171int \hyperlink{classbdm_1_1Kalman_d2c36ba01760bf207b985bf321b7817f}{dimy}}
172\label{classbdm_1_1Kalman_d2c36ba01760bf207b985bf321b7817f}
173
174\begin{CompactList}\small\item\em cache of rvy.count() \item\end{CompactList}\item 
175\hypertarget{classbdm_1_1Kalman_c5136ef617f6ac0e426bea222755d92b}{
176int \hyperlink{classbdm_1_1Kalman_c5136ef617f6ac0e426bea222755d92b}{dimu}}
177\label{classbdm_1_1Kalman_c5136ef617f6ac0e426bea222755d92b}
178
179\begin{CompactList}\small\item\em cache of rvu.count() \item\end{CompactList}\item 
180\hypertarget{classbdm_1_1Kalman_0a2072e2090c10fac74ad30a023a4ace}{
181mat \hyperlink{classbdm_1_1Kalman_0a2072e2090c10fac74ad30a023a4ace}{A}}
182\label{classbdm_1_1Kalman_0a2072e2090c10fac74ad30a023a4ace}
183
184\begin{CompactList}\small\item\em Matrix A. \item\end{CompactList}\item 
185\hypertarget{classbdm_1_1Kalman_5977b2c81857948a35105f0e7840203c}{
186mat \hyperlink{classbdm_1_1Kalman_5977b2c81857948a35105f0e7840203c}{B}}
187\label{classbdm_1_1Kalman_5977b2c81857948a35105f0e7840203c}
188
189\begin{CompactList}\small\item\em Matrix B. \item\end{CompactList}\item 
190\hypertarget{classbdm_1_1Kalman_818eba63a23972786a4579ad30294177}{
191mat \hyperlink{classbdm_1_1Kalman_818eba63a23972786a4579ad30294177}{C}}
192\label{classbdm_1_1Kalman_818eba63a23972786a4579ad30294177}
193
194\begin{CompactList}\small\item\em Matrix C. \item\end{CompactList}\item 
195\hypertarget{classbdm_1_1Kalman_7b56ac423d0654b5755e4f852a870456}{
196mat \hyperlink{classbdm_1_1Kalman_7b56ac423d0654b5755e4f852a870456}{D}}
197\label{classbdm_1_1Kalman_7b56ac423d0654b5755e4f852a870456}
198
199\begin{CompactList}\small\item\em Matrix D. \item\end{CompactList}\item 
200\hypertarget{classbdm_1_1Kalman_70f8bf19e81b532c60fd3a7a152425ee}{
201\hyperlink{classchmat}{chmat} \hyperlink{classbdm_1_1Kalman_70f8bf19e81b532c60fd3a7a152425ee}{Q}}
202\label{classbdm_1_1Kalman_70f8bf19e81b532c60fd3a7a152425ee}
203
204\begin{CompactList}\small\item\em Matrix Q in square-root form. \item\end{CompactList}\item 
205\hypertarget{classbdm_1_1Kalman_475b088287cdfbba4dc60a3d027728b7}{
206\hyperlink{classchmat}{chmat} \hyperlink{classbdm_1_1Kalman_475b088287cdfbba4dc60a3d027728b7}{R}}
207\label{classbdm_1_1Kalman_475b088287cdfbba4dc60a3d027728b7}
208
209\begin{CompactList}\small\item\em Matrix R in square-root form. \item\end{CompactList}\item 
210\hypertarget{classbdm_1_1Kalman_383f329ff18bbe219254c8b3b916f40d}{
211\hyperlink{classbdm_1_1enorm}{enorm}$<$ \hyperlink{classchmat}{chmat} $>$ \hyperlink{classbdm_1_1Kalman_383f329ff18bbe219254c8b3b916f40d}{est}}
212\label{classbdm_1_1Kalman_383f329ff18bbe219254c8b3b916f40d}
213
214\begin{CompactList}\small\item\em posterior density on \$x\_\-t\$ \item\end{CompactList}\item 
215\hypertarget{classbdm_1_1Kalman_ba555c394c429f6831c9bbabfa2c944c}{
216\hyperlink{classbdm_1_1enorm}{enorm}$<$ \hyperlink{classchmat}{chmat} $>$ \hyperlink{classbdm_1_1Kalman_ba555c394c429f6831c9bbabfa2c944c}{fy}}
217\label{classbdm_1_1Kalman_ba555c394c429f6831c9bbabfa2c944c}
218
219\begin{CompactList}\small\item\em preditive density on \$y\_\-t\$ \item\end{CompactList}\item 
220\hypertarget{classbdm_1_1Kalman_bd69dfb802465f22dd84d73a180d5c92}{
221mat \hyperlink{classbdm_1_1Kalman_bd69dfb802465f22dd84d73a180d5c92}{\_\-K}}
222\label{classbdm_1_1Kalman_bd69dfb802465f22dd84d73a180d5c92}
223
224\begin{CompactList}\small\item\em placeholder for Kalman gain \item\end{CompactList}\item 
225\hypertarget{classbdm_1_1Kalman_c249d45258c8578b13858ad3e7b729b1}{
226vec \& \hyperlink{classbdm_1_1Kalman_c249d45258c8578b13858ad3e7b729b1}{\_\-yp}}
227\label{classbdm_1_1Kalman_c249d45258c8578b13858ad3e7b729b1}
228
229\begin{CompactList}\small\item\em cache of fy.mu \item\end{CompactList}\item 
230\hypertarget{classbdm_1_1Kalman_2dd268f2d7fbe6382cb8825a1114192a}{
231\hyperlink{classchmat}{chmat} \& \hyperlink{classbdm_1_1Kalman_2dd268f2d7fbe6382cb8825a1114192a}{\_\-Ry}}
232\label{classbdm_1_1Kalman_2dd268f2d7fbe6382cb8825a1114192a}
233
234\begin{CompactList}\small\item\em cache of fy.R \item\end{CompactList}\item 
235\hypertarget{classbdm_1_1Kalman_fa172078091e45561343fa513dd573b0}{
236vec \& \hyperlink{classbdm_1_1Kalman_fa172078091e45561343fa513dd573b0}{\_\-mu}}
237\label{classbdm_1_1Kalman_fa172078091e45561343fa513dd573b0}
238
239\begin{CompactList}\small\item\em cache of est.mu \item\end{CompactList}\item 
240\hypertarget{classbdm_1_1Kalman_00c27b0bf324f0018497921ca23c71ed}{
241\hyperlink{classchmat}{chmat} \& \hyperlink{classbdm_1_1Kalman_00c27b0bf324f0018497921ca23c71ed}{\_\-P}}
242\label{classbdm_1_1Kalman_00c27b0bf324f0018497921ca23c71ed}
243
244\begin{CompactList}\small\item\em cache of est.R \item\end{CompactList}\item 
245\hypertarget{classbdm_1_1BM_c400357e37d27a4834b2b1d9211009ed}{
246\hyperlink{classbdm_1_1RV}{RV} \hyperlink{classbdm_1_1BM_c400357e37d27a4834b2b1d9211009ed}{drv}}
247\label{classbdm_1_1BM_c400357e37d27a4834b2b1d9211009ed}
248
249\begin{CompactList}\small\item\em Random variable of the data (optional). \item\end{CompactList}\item 
250\hypertarget{classbdm_1_1BM_4064b6559d962633e4372b12f4cd204a}{
251double \hyperlink{classbdm_1_1BM_4064b6559d962633e4372b12f4cd204a}{ll}}
252\label{classbdm_1_1BM_4064b6559d962633e4372b12f4cd204a}
253
254\begin{CompactList}\small\item\em Logarithm of marginalized data likelihood. \item\end{CompactList}\item 
255\hypertarget{classbdm_1_1BM_faff0ad12556fe7dc0e2807d4fd938ee}{
256bool \hyperlink{classbdm_1_1BM_faff0ad12556fe7dc0e2807d4fd938ee}{evalll}}
257\label{classbdm_1_1BM_faff0ad12556fe7dc0e2807d4fd938ee}
258
259\begin{CompactList}\small\item\em If true, the filter will compute likelihood of the data record and store it in {\tt ll} . Set to false if you want to save computational time. \item\end{CompactList}\end{CompactItemize}
260
261
262\subsection{Member Function Documentation}
263\hypertarget{classbdm_1_1BM_c0f027ff91d8459937c6f60ff8e553ff}{
264\index{bdm::EKFCh@{bdm::EKFCh}!\_\-copy\_\-@{\_\-copy\_\-}}
265\index{\_\-copy\_\-@{\_\-copy\_\-}!bdm::EKFCh@{bdm::EKFCh}}
266\subsubsection[\_\-copy\_\-]{\setlength{\rightskip}{0pt plus 5cm}virtual {\bf BM}$\ast$ bdm::BM::\_\-copy\_\- ()\hspace{0.3cm}{\tt  \mbox{[}inline, virtual, inherited\mbox{]}}}}
267\label{classbdm_1_1BM_c0f027ff91d8459937c6f60ff8e553ff}
268
269
270Copy function required in vectors, Arrays of \hyperlink{classbdm_1_1BM}{BM} etc. Have to be DELETED manually! Prototype:
271
272\begin{Code}\begin{verbatim} BM* _copy_(){return new BM(*this);} 
273\end{verbatim}
274\end{Code}
275
276 
277
278Reimplemented in \hyperlink{classbdm_1_1ARX_60c40b5c6abc4c7e464b4ccae64a5a61}{bdm::ARX}.\hypertarget{classbdm_1_1BM_50257e0c1e5b5c73153ea6e716ad8ae0}{
279\index{bdm::EKFCh@{bdm::EKFCh}!logpred@{logpred}}
280\index{logpred@{logpred}!bdm::EKFCh@{bdm::EKFCh}}
281\subsubsection[logpred]{\setlength{\rightskip}{0pt plus 5cm}virtual double bdm::BM::logpred (const vec \& {\em dt}) const\hspace{0.3cm}{\tt  \mbox{[}inline, virtual, inherited\mbox{]}}}}
282\label{classbdm_1_1BM_50257e0c1e5b5c73153ea6e716ad8ae0}
283
284
285Evaluates predictive log-likelihood of the given data record I.e. marginal likelihood of the data with the posterior integrated out.
286
287Reimplemented in \hyperlink{classbdm_1_1ARX_080a7e531e3aa06694112863b15bc6a4}{bdm::ARX}, \hyperlink{classbdm_1_1MixEF_da724da464a75e07521941e430929efa}{bdm::MixEF}, and \hyperlink{classbdm_1_1multiBM_e157b607c1e3fa91d42aeea44458e2bf}{bdm::multiBM}.
288
289Referenced by bdm::BM::logpred\_\-m().
290
291The documentation for this class was generated from the following files:\begin{CompactItemize}
292\item 
293\hyperlink{libKF_8h}{libKF.h}\item 
294libKF.cpp\end{CompactItemize}
Note: See TracBrowser for help on using the browser.