LAPACK
3.4.2
LAPACK: Linear Algebra PACKage
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Functions/Subroutines | |
subroutine | zlarfg (N, ALPHA, X, INCX, TAU) |
ZLARFG generates an elementary reflector (Householder matrix). |
subroutine zlarfg | ( | integer | N, |
complex*16 | ALPHA, | ||
complex*16, dimension( * ) | X, | ||
integer | INCX, | ||
complex*16 | TAU | ||
) |
ZLARFG generates an elementary reflector (Householder matrix).
Download ZLARFG + dependencies [TGZ] [ZIP] [TXT]ZLARFG generates a complex elementary reflector H of order n, such that H**H * ( alpha ) = ( beta ), H**H * H = I. ( x ) ( 0 ) where alpha and beta are scalars, with beta real, and x is an (n-1)-element complex vector. H is represented in the form H = I - tau * ( 1 ) * ( 1 v**H ) , ( v ) where tau is a complex scalar and v is a complex (n-1)-element vector. Note that H is not hermitian. If the elements of x are all zero and alpha is real, then tau = 0 and H is taken to be the unit matrix. Otherwise 1 <= real(tau) <= 2 and abs(tau-1) <= 1 .
[in] | N | N is INTEGER The order of the elementary reflector. |
[in,out] | ALPHA | ALPHA is COMPLEX*16 On entry, the value alpha. On exit, it is overwritten with the value beta. |
[in,out] | X | X is COMPLEX*16 array, dimension (1+(N-2)*abs(INCX)) On entry, the vector x. On exit, it is overwritten with the vector v. |
[in] | INCX | INCX is INTEGER The increment between elements of X. INCX > 0. |
[out] | TAU | TAU is COMPLEX*16 The value tau. |
Definition at line 107 of file zlarfg.f.