##### gehrd

###### Prototype

There is one prototype of `gehrd` available, please see below.

    gehrd( const int_t ilo, const int_t ihi,
            MatrixA& a, VectorTAU& tau );

###### Description

`gehrd` (short for $FRIENDLY_NAME) provides a C++ interface to LAPACK routines SGEHRD, DGEHRD, CGEHRD, and ZGEHRD. `gehrd` reduces a complex general matrix A to upper Hessenberg form H by an unitary similarity transformation: Q' * A * Q = H .

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.

Table 1.226. Dispatching of gehrd

Value type of MatrixA | LAPACK routine
--- | ---
`float` | SGEHRD
`double` | DGEHRD
`complex<float>` | CGEHRD
`complex<double>` | ZGEHRD

###### Definition

Defined in header `boost/numeric/bindings/lapack/computational/gehrd.hpp`.

###### Parameters or Requirements on Types

Parameters

MatrixA

  The definition of term 1

MatrixB

  The definition of term 2

MatrixC

  The definition of term 3.

  Definitions may contain paragraphs.

###### Complexity

###### Example

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

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

this will output

    [5] 0 1 2 3 4 5

###### Notes

###### See Also

- Originating Fortran source files sgehrd.f, dgehrd.f, cgehrd.f, and zgehrd.f at Netlib.