1DLARFP(1) LAPACK auxiliary routine (version 3.2) DLARFP(1)
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6 DLARFP - generates a real elementary reflector H of order n, such that
7 H * ( alpha ) = ( beta ), H' * H = I
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10 SUBROUTINE DLARFP( N, ALPHA, X, INCX, TAU )
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12 INTEGER INCX, N
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14 DOUBLE PRECISION ALPHA, TAU
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16 DOUBLE PRECISION X( * )
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19 DLARFP generates a real elementary reflector H of order n, such that
20 ( x ) ( 0 )
21 where alpha and beta are scalars, beta is non-negative, and x is an
22 (n-1)-element real vector. H is represented in the form
23 H = I - tau * ( 1 ) * ( 1 v' ) ,
24 ( v )
25 where tau is a real scalar and v is a real (n-1)-element
26 vector.
27 If the elements of x are all zero, then tau = 0 and H is taken to be
28 the unit matrix.
29 Otherwise 1 <= tau <= 2.
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32 N (input) INTEGER
33 The order of the elementary reflector.
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35 ALPHA (input/output) DOUBLE PRECISION
36 On entry, the value alpha. On exit, it is overwritten with the
37 value beta.
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39 X (input/output) DOUBLE PRECISION array, dimension
40 (1+(N-2)*abs(INCX)) On entry, the vector x. On exit, it is
41 overwritten with the vector v.
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43 INCX (input) INTEGER
44 The increment between elements of X. INCX > 0.
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46 TAU (output) DOUBLE PRECISION
47 The value tau.
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51 LAPACK auxiliary routine (versionNo3v.e2m)ber 2008 DLARFP(1)