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

6       DLANSY  -  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 matrix A
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SYNOPSIS

11       DOUBLE PRECISION FUNCTION DLANSY( NORM, UPLO, N, A, LDA, WORK )
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13           CHARACTER    NORM, UPLO
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15           INTEGER      LDA, N
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17           DOUBLE       PRECISION A( LDA, * ), WORK( * )
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PURPOSE

20       DLANSY   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 matrix A.
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DESCRIPTION

26       DLANSY returns the value
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28          DLANSY = ( 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 DLANSY as described
46               above.
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48       UPLO    (input) CHARACTER*1
49               Specifies whether the upper or lower  triangular  part  of  the
50               symmetric matrix A is to be referenced.  = 'U':  Upper triangu‐
51               lar part of A is referenced
52               = 'L':  Lower triangular part of A is referenced
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54       N       (input) INTEGER
55               The order of the matrix A.  N >= 0.  When N = 0, DLANSY is  set
56               to zero.
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58       A       (input) DOUBLE PRECISION array, dimension (LDA,N)
59               The  symmetric  matrix  A.   If  UPLO = 'U', the leading n by n
60               upper triangular part of A contains the upper  triangular  part
61               of the matrix A, and the strictly lower triangular part of A is
62               not referenced.  If UPLO = 'L', the leading n by n lower trian‐
63               gular  part  of  A  contains  the  lower triangular part of the
64               matrix A, and the strictly upper triangular part of  A  is  not
65               referenced.
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67       LDA     (input) INTEGER
68               The leading dimension of the array A.  LDA >= max(N,1).
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70       WORK    (workspace) DOUBLE PRECISION array, dimension (MAX(1,LWORK)),
71               where LWORK >= N when NORM = 'I' or '1' or 'O'; otherwise, WORK
72               is not referenced.
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76 LAPACK auxiliary routine (versionNo3v.e1m)ber 2006                       DLANSY(1)
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