qccdatasetmeanvector.3

QccPack implementation in C

.TH QCCDATASETMEANVECTOR 3 "QCCPACK" ""
.SH NAME
QccDatasetMeanVector, QccDatasetCovarianceMatrix
\- calculate first- and second-order statistics of dataset
.SH SYNOPSIS
.B #include "libQccPack.h"
.sp
.BI "int QccDatasetMeanVector(const QccDataset *" dataset ", QccVector " mean );
.br
.sp
.BI "int QccDatasetCovarianceMatrix(const QccDataset *" dataset ", QccMatrix " covariance );
.SH DESCRIPTION
.B QccDatasetMeanVector()
and
.B QccDatasetCovarianceMatrix()
calculate the mean and covariance, respectively, of
.IR dataset .
.LP
.B QccDatasetMeanVector()
returns 
.IR mean ,
a vector of dimension
.I dataset->vector_dimension
that is the average of all the vectors contained in
.IR dataset .
.LP
.B QccDatasetCovarianceMatrix()
returns
.IR covariance ,
a matrix of dimension
.I dataset->vector_dimension 
by
.I dataset->vector_dimension 
that is the covariance matrix of
.IR dataset .
Each vector of 
.I dataset
is considered to be an observation of some random vector process;
.I covariance
is then the covariance matrix of that random vector process.
.LP
For datasets being accessed via block-based access,
.B QccDatasetMeanVector()
and
.B QccDatasetCovarianceMatrix()
calculate the mean and covariance matrix, respectively,
of the current block of the dataset, rather than of the whole file.
.LP
Both
.I mean
and
.I covariance
must be allocated prior to calling 
.B QccDatasetMeanVector()
or
.B QccDatasetCovarianceMatrix()
respectively.
.SH "RETURN VALUE"
On success, 0 is returned.  On error, 1 is returned.
.SH "SEE ALSO"
.BR QccDataset (3),
.BR QccPack (3)
.SH AUTHOR
Copyright (C) 1997-2005  James E. Fowler
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