Prototype

There is one prototype of ungbr available, please see below.

ungbr( const char vect, const int_t m,
        const int_t n, const int_t k, MatrixA& a,
        const VectorTAU& tau );

Description

ungbr (short for $FRIENDLY_NAME) provides a C++ interface to LAPACK routines SORGBR, DORGBR, CUNGBR, and ZUNGBR. ungbr generates one of the complex unitary matrices Q or P*H determined by ZGEBRD when reducing a complex matrix A to bidiagonal form: A = Q * B * PH. Q and P*H are defined as products of elementary reflectors H(i) or G(i) respectively.

If VECT = 'Q', A is assumed to have been an M-by-K matrix, and Q is of order M: if m >= k, Q = H(1) H(2) . . . H(k) and ungbr returns the first n columns of Q, where m >= n >= k; if m < k, Q = H(1) H(2) . . . H(m-1) and ungbr returns Q as an M-by-M matrix.

If VECT = 'P', A is assumed to have been a K-by-N matrix, and P*H is of order N: if k < n, PH = G(k) . . . G(2) G(1) and `ungbr` returns the first m rows of PH, where n >= m >= k; if k >= n, PH = G(n-1) . . . G(2) G(1) and `ungbr` returns P*H as an N-by-N matrix.

The selection of the LAPACK routine is done during compile-time, and is determined by the type of values contained in type MatrixA. The type of values is obtained through the value_type meta-function typename value_type<MatrixA>::type. The dispatching table below illustrates to which specific routine the code path will be generated.

Definition

Defined in header boost/numeric/bindings/lapack/computational/ungbr.hpp.

Parameters or Requirements on Types

Complexity

Example

#include <boost/numeric/bindings/lapack/computational/ungbr.hpp>
using namespace boost::numeric::bindings;

lapack::ungbr( x, y, z );

this will output

[5] 0 1 2 3 4 5

Notes

See Also