Prototype

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

langb( const char norm, const MatrixAB& ab );

Description

langb (short for $FRIENDLY_NAME) provides a C++ interface to LAPACK routines SLANGB, DLANGB, CLANGB, and ZLANGB. langb returns the value of the one norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of an n by n band matrix A, with kl sub-diagonals and ku super-diagonals.

Description =====

langb returns the value

langb = ( max(abs(A(i,j))), NORM = 'M' or 'm' ( ( norm1(A), NORM = '1', 'O' or 'o' ( ( normI(A), NORM = 'I' or 'i' ( ( normF(A), NORM = 'F', 'f', 'E' or 'e'

where norm1 denotes the one norm of a matrix (maximum column sum), normI denotes the infinity norm of a matrix (maximum row sum) and normF denotes the Frobenius norm of a matrix (square root of sum of squares). Note that max(abs(A(i,j))) is not a consistent matrix norm.

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

Definition

Defined in header boost/numeric/bindings/lapack/auxiliary/langb.hpp.

Parameters or Requirements on Types

Complexity

Example

#include <boost/numeric/bindings/lapack/auxiliary/langb.hpp>
using namespace boost::numeric::bindings;

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

this will output

[5] 0 1 2 3 4 5

Notes

See Also