zlaipd.f

Go to the documentation of this file.

*> \brief \b ZLAIPD
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at
*            http://www.netlib.org/lapack/explore-html/
*
*  Definition:
*  ===========
*
*       SUBROUTINE ZLAIPD( N, A, INDA, VINDA )
*
*       .. Scalar Arguments ..
*       INTEGER            INDA, N, VINDA
*       ..
*       .. Array Arguments ..
*       COMPLEX*16         A( * )
*       ..
*
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> ZLAIPD sets the imaginary part of the diagonal elements of a complex
*> matrix A to a large value.  This is used to test LAPACK routines for
*> complex Hermitian matrices, which are not supposed to access or use
*> the imaginary parts of the diagonals.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>         The number of diagonal elements of A.
*> \endverbatim
*>
*> \param[in,out] A
*> \verbatim
*>          A is COMPLEX*16 array, dimension
*>                        (1+(N-1)*INDA+(N-2)*VINDA)
*>         On entry, the complex (Hermitian) matrix A.
*>         On exit, the imaginary parts of the diagonal elements are set
*>         to BIGNUM = EPS / SAFMIN, where EPS is the machine epsilon and
*>         SAFMIN is the safe minimum.
*> \endverbatim
*>
*> \param[in] INDA
*> \verbatim
*>          INDA is INTEGER
*>         The increment between A(1) and the next diagonal element of A.
*>         Typical values are
*>         = LDA+1:  square matrices with leading dimension LDA
*>         = 2:  packed upper triangular matrix, starting at A(1,1)
*>         = N:  packed lower triangular matrix, starting at A(1,1)
*> \endverbatim
*>
*> \param[in] VINDA
*> \verbatim
*>          VINDA is INTEGER
*>         The change in the diagonal increment between columns of A.
*>         Typical values are
*>         = 0:  no change, the row and column increments in A are fixed
*>         = 1:  packed upper triangular matrix
*>         = -1:  packed lower triangular matrix
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \ingroup complex16_lin
*
*  =====================================================================
      SUBROUTINE zlaipd( N, A, INDA, VINDA )
*
*  -- LAPACK test routine --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*
*     .. Scalar Arguments ..
      INTEGER            INDA, N, VINDA
*     ..
*     .. Array Arguments ..
      COMPLEX*16         A( * )
*     ..
*
*  =====================================================================
*
*     .. Local Scalars ..
      INTEGER            I, IA, IXA
      DOUBLE PRECISION   BIGNUM
*     ..
*     .. External Functions ..
      DOUBLE PRECISION   DLAMCH
      EXTERNAL           dlamch
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          dble, dcmplx
*     ..
*     .. Executable Statements ..
*
      bignum = dlamch( 'Epsilon' ) / dlamch( 'Safe minimum' )
      ia = 1
      ixa = inda
      DO 10 i = 1, n
         a( ia ) = dcmplx( dble( a( ia ) ), bignum )
         ia = ia + ixa
         ixa = ixa + vinda
   10 CONTINUE
      RETURN
      END