NAME

       double_eig

SYNOPSIS

   Functions
       subroutine dlarfy (UPLO, N, V, INCV, TAU, C, LDC, WORK)
           DLARFY

Detailed Description

       This is the group of double LAPACK TESTING EIG routines.

Function Documentation

   subroutine dlarfy (character UPLO, integer N, double precision, dimension( * ) V, integer
       INCV, double precision TAU, double precision, dimension( ldc, * ) C, integer LDC, double
       precision, dimension( * ) WORK)
       DLARFY

       Purpose:

            DLARFY applies an elementary reflector, or Householder matrix, H,
            to an n x n symmetric matrix C, from both the left and the right.

            H is represented in the form

               H = I - tau * v * v'

            where  tau  is a scalar and  v  is a vector.

            If  tau  is  zero, then  H  is taken to be the unit matrix.

       Parameters:
           UPLO

                     UPLO is CHARACTER*1
                     Specifies whether the upper or lower triangular part of the
                     symmetric matrix C is stored.
                     = 'U':  Upper triangle
                     = 'L':  Lower triangle

           N

                     N is INTEGER
                     The number of rows and columns of the matrix C.  N >= 0.

           V

                     V is DOUBLE PRECISION array, dimension
                             (1 + (N-1)*abs(INCV))
                     The vector v as described above.

           INCV

                     INCV is INTEGER
                     The increment between successive elements of v.  INCV must
                     not be zero.

           TAU

                     TAU is DOUBLE PRECISION
                     The value tau as described above.

           C

                     C is DOUBLE PRECISION array, dimension (LDC, N)
                     On entry, the matrix C.
                     On exit, C is overwritten by H * C * H'.

           LDC

                     LDC is INTEGER
                     The leading dimension of the array C.  LDC >= max( 1, N ).

           WORK

                     WORK is DOUBLE PRECISION array, dimension (N)

       Author:
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Date:
           December 2016

Author

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