1CHER2(1)                         BLAS routine                         CHER2(1)
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NAME

6       CHER2  -  the  hermitian  rank 2 operation   A := alpha*x*conjg( y' ) +
7       conjg( alpha )*y*conjg( x' ) + A,
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SYNOPSIS

10       SUBROUTINE CHER2(UPLO,N,ALPHA,X,INCX,Y,INCY,A,LDA)
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12           COMPLEX                                        ALPHA
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14           INTEGER                                        INCX,INCY,LDA,N
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16           CHARACTER                                      UPLO
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18           COMPLEX                                        A(LDA,*),X(*),Y(*)
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PURPOSE

21       CHER2  performs the hermitian rank 2 operation
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23       where alpha is a scalar, x and y are n element vectors and A is an n by
24       n hermitian matrix.
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ARGUMENTS

28       UPLO   - CHARACTER*1.
29              On  entry,  UPLO specifies whether the upper or lower triangular
30              part of the array A is to be referenced as follows:
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32              UPLO = 'U' or 'u'   Only the upper triangular part of A is to be
33              referenced.
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35              UPLO = 'L' or 'l'   Only the lower triangular part of A is to be
36              referenced.
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38              Unchanged on exit.
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40       N      - INTEGER.
41              On entry, N specifies the order of the matrix A.  N must  be  at
42              least zero.  Unchanged on exit.
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44       ALPHA  - COMPLEX         .
45              On entry, ALPHA specifies the scalar alpha.  Unchanged on exit.
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47       X      - COMPLEX          array of dimension at least
48              (  1  +  ( n - 1 )*abs( INCX ) ).  Before entry, the incremented
49              array X must contain the n element vector x.  Unchanged on exit.
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51       INCX   - INTEGER.
52              On entry, INCX specifies the increment for the  elements  of  X.
53              INCX must not be zero.  Unchanged on exit.
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55       Y      - COMPLEX          array of dimension at least
56              (  1  +  ( n - 1 )*abs( INCY ) ).  Before entry, the incremented
57              array Y must contain the n element vector y.  Unchanged on exit.
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59       INCY   - INTEGER.
60              On entry, INCY specifies the increment for the  elements  of  Y.
61              INCY must not be zero.  Unchanged on exit.
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63       A      - COMPLEX          array of DIMENSION ( LDA, n ).
64              Before  entry  with  UPLO = 'U' or 'u', the leading n by n upper
65              triangular part of the array A must contain the upper triangular
66              part  of  the hermitian matrix and the strictly lower triangular
67              part of A is not referenced. On exit, the upper triangular  part
68              of  the  array  A is overwritten by the upper triangular part of
69              the updated matrix.  Before entry with UPLO = 'L'  or  'l',  the
70              leading n by n lower triangular part of the array A must contain
71              the lower triangular  part  of  the  hermitian  matrix  and  the
72              strictly  upper triangular part of A is not referenced. On exit,
73              the lower triangular part of the array A is overwritten  by  the
74              lower  triangular  part  of  the  updated matrix.  Note that the
75              imaginary parts of the diagonal elements need not be  set,  they
76              are assumed to be zero, and on exit they are set to zero.
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78       LDA    - INTEGER.
79              On  entry, LDA specifies the first dimension of A as declared in
80              the calling (sub) program. LDA must be at least  max(  1,  n  ).
81              Unchanged on exit.
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83              Level 2 Blas routine.
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85              --  Written on 22-October-1986.  Jack Dongarra, Argonne National
86              Lab.  Jeremy Du Croz, Nag Central Office.  Sven Hammarling,  Nag
87              Central Office.  Richard Hanson, Sandia National Labs.
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91BLAS routine                     November 2006                        CHER2(1)