1SSYR(1)                          BLAS routine                          SSYR(1)
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NAME

6       SSYR - the symmetric rank 1 operation   A := alpha*x*x' + A,
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SYNOPSIS

9       SUBROUTINE SSYR(UPLO,N,ALPHA,X,INCX,A,LDA)
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11           REAL                                   ALPHA
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13           INTEGER                                INCX,LDA,N
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15           CHARACTER                              UPLO
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17           REAL                                   A(LDA,*),X(*)
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PURPOSE

20       SSYR   performs the symmetric rank 1 operation
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22       where alpha is a real scalar, x is an n element vector and A is an n by
23       n symmetric matrix.
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ARGUMENTS

27       UPLO   - CHARACTER*1.
28              On entry, UPLO specifies whether the upper or  lower  triangular
29              part of the array A is to be referenced as follows:
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31              UPLO = 'U' or 'u'   Only the upper triangular part of A is to be
32              referenced.
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34              UPLO = 'L' or 'l'   Only the lower triangular part of A is to be
35              referenced.
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37              Unchanged on exit.
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39       N      - INTEGER.
40              On  entry,  N specifies the order of the matrix A.  N must be at
41              least zero.  Unchanged on exit.
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43       ALPHA  - REAL            .
44              On entry, ALPHA specifies the scalar alpha.  Unchanged on exit.
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46       X      - REAL             array of dimension at least
47              ( 1 + ( n - 1 )*abs( INCX ) ).  Before  entry,  the  incremented
48              array X must contain the n element vector x.  Unchanged on exit.
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50       INCX   - INTEGER.
51              On  entry,  INCX  specifies the increment for the elements of X.
52              INCX must not be zero.  Unchanged on exit.
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54       A      - REAL             array of DIMENSION ( LDA, n ).
55              Before entry with  UPLO = 'U' or 'u', the leading n by  n  upper
56              triangular part of the array A must contain the upper triangular
57              part of the symmetric matrix and the strictly  lower  triangular
58              part  of A is not referenced. On exit, the upper triangular part
59              of the array A is overwritten by the upper  triangular  part  of
60              the  updated  matrix.   Before entry with UPLO = 'L' or 'l', the
61              leading n by n lower triangular part of the array A must contain
62              the  lower  triangular  part  of  the  symmetric  matrix and the
63              strictly upper triangular part of A is not referenced. On  exit,
64              the  lower  triangular part of the array A is overwritten by the
65              lower triangular part of the updated matrix.
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67       LDA    - INTEGER.
68              On entry, LDA specifies the first dimension of A as declared  in
69              the  calling  (sub)  program.  LDA must be at least max( 1, n ).
70              Unchanged on exit.
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72              Level 2 Blas routine.
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74              -- Written on 22-October-1986.  Jack Dongarra, Argonne  National
75              Lab.   Jeremy Du Croz, Nag Central Office.  Sven Hammarling, Nag
76              Central Office.  Richard Hanson, Sandia National Labs.
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80BLAS routine                     November 2006                         SSYR(1)
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