1CLANGT(1)           LAPACK auxiliary routine (version 3.1)           CLANGT(1)
2
3
4

NAME

6       CLANGT  -  the  value  of  the  one norm, or the Frobenius norm, or the
7       infinity norm, or the element of largest absolute value  of  a  complex
8       tridiagonal matrix A
9

SYNOPSIS

11       REAL FUNCTION CLANGT( NORM, N, DL, D, DU )
12
13           CHARACTER NORM
14
15           INTEGER   N
16
17           COMPLEX   D( * ), DL( * ), DU( * )
18

PURPOSE

20       CLANGT   returns  the value of the one norm,  or the Frobenius norm, or
21       the  infinity norm,  or the  element of  largest absolute value   of  a
22       complex tridiagonal matrix A.
23
24

DESCRIPTION

26       CLANGT returns the value
27
28          CLANGT = ( max(abs(A(i,j))), NORM = 'M' or 'm'
29                   (
30                   ( norm1(A),         NORM = '1', 'O' or 'o'
31                   (
32                   ( normI(A),         NORM = 'I' or 'i'
33                   (
34                   ( normF(A),         NORM = 'F', 'f', 'E' or 'e'
35
36       where   norm1   denotes the  one norm of a matrix (maximum column sum),
37       normI  denotes the  infinity norm  of a matrix  (maximum row  sum)  and
38       normF   denotes  the  Frobenius norm of a matrix (square root of sum of
39       squares).  Note that  max(abs(A(i,j)))   is  not  a  consistent  matrix
40       norm.
41
42

ARGUMENTS

44       NORM    (input) CHARACTER*1
45               Specifies  the  value  to  be  returned  in CLANGT as described
46               above.
47
48       N       (input) INTEGER
49               The order of the matrix A.  N >= 0.  When N = 0, CLANGT is  set
50               to zero.
51
52       DL      (input) COMPLEX array, dimension (N-1)
53               The (n-1) sub-diagonal elements of A.
54
55       D       (input) COMPLEX array, dimension (N)
56               The diagonal elements of A.
57
58       DU      (input) COMPLEX array, dimension (N-1)
59               The (n-1) super-diagonal elements of A.
60
61
62
63 LAPACK auxiliary routine (versionNo3v.e1m)ber 2006                       CLANGT(1)