SRC/zlangb.f(3)

NAME
SRC/zlangb.f

SYNOPSIS

  Functions/Subroutines
double precision function zlangb (norm, n, kl, ku, ab, ldab, work)
ZLANGB returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of general band matrix.

Function/Subroutine Documentation

  double precision function zlangb (character norm, integer n, integer kl, integer ku, complex*16, dimension( ldab, * ) ab, integer ldab, double precision, dimension( * ) work)

ZLANGB returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of general band matrix.

Purpose:

     ZLANGB  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.

Returns
    ZLANGB

        ZLANGB = ( 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.

Parameters
    NORM

              NORM is CHARACTER*1
              Specifies the value to be returned in ZLANGB as described
              above.

    N

              N is INTEGER
              The order of the matrix A.  N >= 0.  When N = 0, ZLANGB is
              set to zero.

    KL

              KL is INTEGER
              The number of sub-diagonals of the matrix A.  KL >= 0.

    KU

              KU is INTEGER
              The number of super-diagonals of the matrix A.  KU >= 0.

    AB

              AB is COMPLEX*16 array, dimension (LDAB,N)
              The band matrix A, stored in rows 1 to KL+KU+1.  The j-th
              column of A is stored in the j-th column of the array AB as
              follows:
              AB(ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(n,j+kl).

    LDAB

              LDAB is INTEGER
              The leading dimension of the array AB.  LDAB >= KL+KU+1.

    WORK

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

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 123 of file zlangb.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.