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## zspmv()

subroutine zspmv | ( | character | uplo,
|  | integer | n,
|  | complex*16 | alpha,
|  | complex*16, dimension( * ) | ap,
|  | complex*16, dimension( * ) | x,
|  | integer | incx,
|  | complex*16 | beta,
|  | complex*16, dimension( * ) | y,
|  | integer | incy )

ZSPMV computes a matrix-vector product for complex vectors using a complex symmetric packed matrix

Download ZSPMV + dependencies [TGZ] [ZIP] [TXT]

Purpose:

      !>
      !> ZSPMV  performs the matrix-vector operation
      !>
      !>    y := alpha*A*x + beta*y,
      !>
      !> where alpha and beta are scalars, x and y are n element vectors and
      !> A is an n by n symmetric matrix, supplied in packed form.
      !>

Parameters

  [in]

  UPLO

      !>          UPLO is CHARACTER*1
      !>           On entry, UPLO specifies whether the upper or lower
      !>           triangular part of the matrix A is supplied in the packed
      !>           array AP as follows:
      !>
      !>              UPLO = 'U' or 'u'   The upper triangular part of A is
      !>                                  supplied in AP.
      !>
      !>              UPLO = 'L' or 'l'   The lower triangular part of A is
      !>                                  supplied in AP.
      !>
      !>           Unchanged on exit.
      !>

  [in]

  N

      !>          N is INTEGER
      !>           On entry, N specifies the order of the matrix A.
      !>           N must be at least zero.
      !>           Unchanged on exit.
      !>

  [in]

  ALPHA

      !>          ALPHA is COMPLEX*16
      !>           On entry, ALPHA specifies the scalar alpha.
      !>           Unchanged on exit.
      !>

  [in]

  AP

      !>          AP is COMPLEX*16 array, dimension at least
      !>           ( ( N*( N + 1 ) )/2 ).
      !>           Before entry, with UPLO = 'U' or 'u', the array AP must
      !>           contain the upper triangular part of the symmetric matrix
      !>           packed sequentially, column by column, so that AP( 1 )
      !>           contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 1, 2 )
      !>           and a( 2, 2 ) respectively, and so on.
      !>           Before entry, with UPLO = 'L' or 'l', the array AP must
      !>           contain the lower triangular part of the symmetric matrix
      !>           packed sequentially, column by column, so that AP( 1 )
      !>           contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 2, 1 )
      !>           and a( 3, 1 ) respectively, and so on.
      !>           Unchanged on exit.
      !>

  [in]

  X

      !>          X is COMPLEX*16 array, dimension at least
      !>           ( 1 + ( N - 1 )*abs( INCX ) ).
      !>           Before entry, the incremented array X must contain the N-
      !>           element vector x.
      !>           Unchanged on exit.
      !>

  [in]

  INCX

      !>          INCX is INTEGER
      !>           On entry, INCX specifies the increment for the elements of
      !>           X. INCX must not be zero.
      !>           Unchanged on exit.
      !>

  [in]

  BETA

      !>          BETA is COMPLEX*16
      !>           On entry, BETA specifies the scalar beta. When BETA is
      !>           supplied as zero then Y need not be set on input.
      !>           Unchanged on exit.
      !>

  [in,out]

  Y

      !>          Y is COMPLEX*16 array, dimension at least
      !>           ( 1 + ( N - 1 )*abs( INCY ) ).
      !>           Before entry, the incremented array Y must contain the n
      !>           element vector y. On exit, Y is overwritten by the updated
      !>           vector y.
      !>

  [in]

  INCY

      !>          INCY is INTEGER
      !>           On entry, INCY specifies the increment for the elements of
      !>           Y. INCY must not be zero.
      !>           Unchanged on exit.
      !>

Author
  Univ. of Tennessee
  Univ. of California Berkeley
  Univ. of Colorado Denver
  NAG Ltd.