1DLANST(1)           LAPACK auxiliary routine (version 3.1)           DLANST(1)
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NAME

6       DLANST  -  the  value  of  the  one norm, or the Frobenius norm, or the
7       infinity norm, or the element of largest absolute value of a real  sym‐
8       metric tridiagonal matrix A
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SYNOPSIS

11       DOUBLE PRECISION FUNCTION DLANST( NORM, N, D, E )
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13           CHARACTER    NORM
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15           INTEGER      N
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17           DOUBLE       PRECISION D( * ), E( * )
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PURPOSE

20       DLANST   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       real symmetric tridiagonal matrix A.
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DESCRIPTION

26       DLANST returns the value
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28          DLANST = ( 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'
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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.
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ARGUMENTS

44       NORM    (input) CHARACTER*1
45               Specifies  the  value  to  be  returned  in DLANST as described
46               above.
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48       N       (input) INTEGER
49               The order of the matrix A.  N >= 0.  When N = 0, DLANST is  set
50               to zero.
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52       D       (input) DOUBLE PRECISION array, dimension (N)
53               The diagonal elements of A.
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55       E       (input) DOUBLE PRECISION array, dimension (N-1)
56               The (n-1) sub-diagonal or super-diagonal elements of A.
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60 LAPACK auxiliary routine (versionNo3v.e1m)ber 2006                       DLANST(1)
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