##### larrb

###### Prototype

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

    larrb( const int_t n, const VectorD& d, const VectorLLD& lld,
            const int_t ifirst, const int_t ilast,
            const Scalar >, const Scalar >, const int_t offset,
            VectorW& w, VectorWGAP& wgap, VectorWERR& werr, const Scalar >,
            const Scalar >, const int_t twist );

###### Description

`larrb` (short for $FRIENDLY_NAME) provides a C++ interface to LAPACK routines SLARRB and DLARRB. Given the relatively robust representation(RRR) L D L^T, `larrb` does "limited" bisection to refine the eigenvalues of L D L^T, W( IFIRST-OFFSET ) through W( ILAST-OFFSET ), to more accuracy. Initial guesses for these eigenvalues are input in W, the corresponding estimate of the error in these guesses and their gaps are input in WERR and WGAP, respectively. During bisection, intervals [left, right] are maintained by storing their mid-points and semi-widths in the arrays W and WERR respectively.

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

Table 1.347. Dispatching of larrb

Value type of VectorD | LAPACK routine
--- | ---
`float` | SLARRB
`double` | DLARRB

###### Definition

Defined in header `boost/numeric/bindings/lapack/auxiliary/larrb.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/auxiliary/larrb.hpp>
    using namespace boost::numeric::bindings;

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

this will output

    [5] 0 1 2 3 4 5

###### Notes

###### See Also

- Originating Fortran source files slarrb.f and dlarrb.f at Netlib.