[ новости /+++ | форум | теги | ]

NAME
     dlansb - return the value of the one norm, or the  Frobenius
     norm,  or the infinity norm, or the element of largest abso-
     lute value of an n by n symmetric  band  matrix  A,  with  k
     super-diagonals

SYNOPSIS
     DOUBLE PRECISION FUNCTION DLANSB(  NORM,  UPLO,  N,  K,  AB,
               LDAB, WORK )

     CHARACTER NORM, UPLO

     INTEGER K, LDAB, N

     DOUBLE PRECISION AB( LDAB, * ), WORK( * )



     #include <sunperf.h>

     double dlansb(char norm, char uplo, int  n,  int  k,  double
               *dab, int ldab ) ;

PURPOSE
     DLANSB  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 symmetric band matrix A,   with
     k super-diagonals.


DESCRIPTION
     DLANSB returns the value

        DLANSB = ( 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  matrix norm.


ARGUMENTS
     NORM      (input) CHARACTER*1
               Specifies the value to be returned  in  DLANSB  as
               described above.

     UPLO      (input) CHARACTER*1
               Specifies whether the upper  or  lower  triangular
               part  of  the  band  matrix A is supplied.  = 'U':
               Upper triangular part is supplied
               = 'L':  Lower triangular part is supplied

     N         (input) INTEGER
               The order of the matrix A.  N >= 0.  When N  =  0,
               DLANSB is set to zero.

     K         (input) INTEGER
               The number of super-diagonals or sub-diagonals  of
               the band matrix A.  K >= 0.

     AB        (input) DOUBLE PRECISION array, dimension (LDAB,N)
               The upper or lower triangle of the symmetric  band
               matrix A, stored in the first K+1 rows of AB.  The
               j-th column of A is stored in the j-th  column  of
               the   array   AB  as  follows:   if  UPLO  =  'U',
               AB(k+1+i-j,j) = A(i,j)  for  max(1,j-k)<=i<=j;  if
               UPLO   =   'L',   AB(1+i-j,j)     =   A(i,j)   for
               j<=i<=min(n,j+k).

     LDAB      (input) INTEGER
               The leading dimension of the array  AB.   LDAB  >=
               K+1.

     WORK      (workspace)  DOUBLE  PRECISION  array,   dimension
               (LWORK),
               where LWORK >= N when NORM = 'I' or  '1'  or  'O';
               otherwise, WORK is not referenced.

Партнёры:

Хостинг: