slangt.f - Man Page

SRC/slangt.f

Synopsis

Functions/Subroutines

real function slangt (norm, n, dl, d, du)
SLANGT returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of a general tridiagonal matrix.

Function/Subroutine Documentation

real function slangt (character norm, integer n, real, dimension( * ) dl, real, dimension( * ) d, real, dimension( * ) du)

SLANGT returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of a general tridiagonal matrix.  

Purpose:

 SLANGT  returns the value of the one norm,  or the Frobenius norm, or
 the  infinity norm,  or the  element of  largest absolute value  of a
 real tridiagonal matrix A.
Returns

SLANGT

    SLANGT = ( 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 SLANGT as described
          above.

N

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

DL

          DL is REAL array, dimension (N-1)
          The (n-1) sub-diagonal elements of A.

D

          D is REAL array, dimension (N)
          The diagonal elements of A.

DU

          DU is REAL array, dimension (N-1)
          The (n-1) super-diagonal elements of A.
Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 105 of file slangt.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

The man page slangt(3) is an alias of slangt.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK