CVR-Lib last update 20 Sep 2009

Unassigned Classes and Data Structures

Please assign this classes to one of the functionality groups of the CVR-Lib. More...


Functions

template<typename T >
void cvr::householder (vector< T > &v, T &beta)
template<typename T >
void cvr::householder (const vector< T > &src, vector< T > &v, T &beta)
template<typename T >
void cvr::givens (const T &a, const T &b, T &c, T &s)


Detailed Description

Please assign this classes to one of the functionality groups of the CVR-Lib.

If your class does not fit into any of the current groups, please insert a new one in cvrlib/doc/src/cvrGroups.h


Function Documentation

template<typename T >
void cvr::givens ( const T &  a,
const T &  b,
T &  c,
T &  s 
) [inline]

Calculates the cos (c) and sin (s) values needed for Givens Rotations.

The values c and s have the following property:

\[ \begin{bmatrix} c & s \\ -s & c \end{bmatrix}^T \begin{bmatrix} a \\ b \end{bmatrix} = \begin{bmatrix} r \\ 0 \end{bmatrix}. \]

For more details see:
Gene H. Golub and Charles F. Van Loan, "Matrix Computations", 1996, The John Hopkins University Press, Baltimore and London

Parameters:
a first scalar
b second scalar
c cos value for Givens Rotation
s sin value for Givens Rotation

template<typename T >
void cvr::householder ( const vector< T > &  src,
vector< T > &  v,
T &  beta 
) [inline]

Calculates the Householder vector v and the factor beta for a vector src.

The resulting n-dimensional vector v has the following properties:

  • v[0] = 1,
  • $ P = I_n - \beta v v^T$ is orthogonal, and
  • /f$ Px=||x||_2e_1 , where I_n is the n-by-n identity matrix and e_1 the first canonical vector.

Note: The on-place version of householder(vector<T>&, T&) is faster since the input vector is not copied first.

For more details see:
Gene H. Golub and Charles F. Van Loan, "Matrix Computations", 1996, The John Hopkins University Press, Baltimore and London

Parameters:
src vector x used to form the householder vector
v householder vector v
beta factor needed for householder transform

template<typename T >
void cvr::householder ( vector< T > &  v,
T &  beta 
) [inline]

Calculates the Householder vector v and the factor beta for a vector x (given as input in v).

The resulting n-dimensional vector v has the following properties:

  • v[0] = 1,
  • $ P = I_n - \beta v v^T$ is orthogonal, and
  • /f$ Px=||x||_2e_1 , where I_n is the n-by-n identity matrix and e_1 the first canonical vector.

For more details see:
Gene H. Golub and Charles F. Van Loan, "Matrix Computations", 1996, The John Hopkins University Press, Baltimore and London

Parameters:
v input: vector x; output: householder vector v
beta factor needed for householder transform


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