##### spgvx

###### Prototype

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

    spgvx( const int_t itype, const char jobz, const char range,
            MatrixAP& ap, MatrixBP& bp, const Scalar >, const Scalar >,
            const int_t il, const int_t iu,
            const Scalar >, int_t& m, VectorW& w, MatrixZ& z,
            VectorIFAIL& ifail );

###### Description

`spgvx` (short for $FRIENDLY_NAME) provides a C++ interface to LAPACK routines SSPGVX and DSPGVX. `spgvx` computes selected eigenvalues, and optionally, eigenvectors of a real generalized symmetric-definite eigenproblem, of the form A*x`(lambda)*B*x, A*Bx`(lambda)*x, or B*A*x=(lambda)*x. Here A and B are assumed to be symmetric, stored in packed storage, and B is also positive definite. Eigenvalues and eigenvectors can be selected by specifying either a range of values or a range of indices for the desired eigenvalues.

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

Table 1.120. Dispatching of spgvx

Value type of MatrixAP | LAPACK routine
--- | ---
`float` | SSPGVX
`double` | DSPGVX

###### Definition

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

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

this will output

    [5] 0 1 2 3 4 5

###### Notes

###### See Also

- Originating Fortran source files sspgvx.f and dspgvx.f at Netlib.