LAPACK  3.6.1 LAPACK: Linear Algebra PACKage
slarscl2.f
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1 *> \brief \b SLARSCL2 performs reciprocal diagonal scaling on a vector.
2 *
3 * =========== DOCUMENTATION ===========
4 *
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17 *
18 * Definition:
19 * ===========
20 *
21 * SUBROUTINE SLARSCL2 ( M, N, D, X, LDX )
22 *
23 * .. Scalar Arguments ..
24 * INTEGER M, N, LDX
25 * ..
26 * .. Array Arguments ..
27 * REAL D( * ), X( LDX, * )
28 * ..
29 *
30 *
31 *> \par Purpose:
32 * =============
33 *>
34 *> \verbatim
35 *>
36 *> SLARSCL2 performs a reciprocal diagonal scaling on an vector:
37 *> x <-- inv(D) * x
38 *> where the diagonal matrix D is stored as a vector.
39 *>
40 *> Eventually to be replaced by BLAS_sge_diag_scale in the new BLAS
41 *> standard.
42 *> \endverbatim
43 *
44 * Arguments:
45 * ==========
46 *
47 *> \param[in] M
48 *> \verbatim
49 *> M is INTEGER
50 *> The number of rows of D and X. M >= 0.
51 *> \endverbatim
52 *>
53 *> \param[in] N
54 *> \verbatim
55 *> N is INTEGER
56 *> The number of columns of X. N >= 0.
57 *> \endverbatim
58 *>
59 *> \param[in] D
60 *> \verbatim
61 *> D is REAL array, length M
62 *> Diagonal matrix D, stored as a vector of length M.
63 *> \endverbatim
64 *>
65 *> \param[in,out] X
66 *> \verbatim
67 *> X is REAL array, dimension (LDX,N)
68 *> On entry, the vector X to be scaled by D.
69 *> On exit, the scaled vector.
70 *> \endverbatim
71 *>
72 *> \param[in] LDX
73 *> \verbatim
74 *> LDX is INTEGER
75 *> The leading dimension of the vector X. LDX >= M.
76 *> \endverbatim
77 *
78 * Authors:
79 * ========
80 *
81 *> \author Univ. of Tennessee
82 *> \author Univ. of California Berkeley
83 *> \author Univ. of Colorado Denver
84 *> \author NAG Ltd.
85 *
86 *> \date June 2016
87 *
88 *> \ingroup realOTHERcomputational
89 *
90 * =====================================================================
91  SUBROUTINE slarscl2 ( M, N, D, X, LDX )
92 *
93 * -- LAPACK computational routine (version 3.6.1) --
94 * -- LAPACK is a software package provided by Univ. of Tennessee, --
95 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
96 * June 2016
97 *
98 * .. Scalar Arguments ..
99  INTEGER M, N, LDX
100 * ..
101 * .. Array Arguments ..
102  REAL D( * ), X( ldx, * )
103 * ..
104 *
105 * =====================================================================
106 *
107 * .. Local Scalars ..
108  INTEGER I, J
109 * ..
110 * .. Executable Statements ..
111 *
112  DO j = 1, n
113  DO i = 1, m
114  x( i, j ) = x( i, j ) / d( i )
115  END DO
116  END DO
117
118  RETURN
119  END
subroutine slarscl2(M, N, D, X, LDX)
SLARSCL2 performs reciprocal diagonal scaling on a vector.
Definition: slarscl2.f:92