LAPACK  3.5.0
LAPACK: Linear Algebra PACKage
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dlarfy.f File Reference

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Functions/Subroutines

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

Function/Subroutine 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
[in]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
[in]N
          N is INTEGER
          The number of rows and columns of the matrix C.  N >= 0.
[in]V
          V is DOUBLE PRECISION array, dimension
                  (1 + (N-1)*abs(INCV))
          The vector v as described above.
[in]INCV
          INCV is INTEGER
          The increment between successive elements of v.  INCV must
          not be zero.
[in]TAU
          TAU is DOUBLE PRECISION
          The value tau as described above.
[in,out]C
          C is DOUBLE PRECISION array, dimension (LDC, N)
          On entry, the matrix C.
          On exit, C is overwritten by H * C * H'.
[in]LDC
          LDC is INTEGER
          The leading dimension of the array C.  LDC >= max( 1, N ).
[out]WORK
          WORK is DOUBLE PRECISION array, dimension (N)
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date
November 2011

Definition at line 109 of file dlarfy.f.

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