Annotation of rpl/lapack/lapack/dlaset.f, revision 1.13
1.11 bertrand 1: *> \brief \b DLASET initializes the off-diagonal elements and the diagonal elements of a matrix to given values.
1.8 bertrand 2: *
3: * =========== DOCUMENTATION ===========
4: *
5: * Online html documentation available at
6: * http://www.netlib.org/lapack/explore-html/
7: *
8: *> \htmlonly
9: *> Download DLASET + dependencies
10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlaset.f">
11: *> [TGZ]</a>
12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlaset.f">
13: *> [ZIP]</a>
14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlaset.f">
15: *> [TXT]</a>
16: *> \endhtmlonly
17: *
18: * Definition:
19: * ===========
20: *
21: * SUBROUTINE DLASET( UPLO, M, N, ALPHA, BETA, A, LDA )
22: *
23: * .. Scalar Arguments ..
24: * CHARACTER UPLO
25: * INTEGER LDA, M, N
26: * DOUBLE PRECISION ALPHA, BETA
27: * ..
28: * .. Array Arguments ..
29: * DOUBLE PRECISION A( LDA, * )
30: * ..
31: *
32: *
33: *> \par Purpose:
34: * =============
35: *>
36: *> \verbatim
37: *>
38: *> DLASET initializes an m-by-n matrix A to BETA on the diagonal and
39: *> ALPHA on the offdiagonals.
40: *> \endverbatim
41: *
42: * Arguments:
43: * ==========
44: *
45: *> \param[in] UPLO
46: *> \verbatim
47: *> UPLO is CHARACTER*1
48: *> Specifies the part of the matrix A to be set.
49: *> = 'U': Upper triangular part is set; the strictly lower
50: *> triangular part of A is not changed.
51: *> = 'L': Lower triangular part is set; the strictly upper
52: *> triangular part of A is not changed.
53: *> Otherwise: All of the matrix A is set.
54: *> \endverbatim
55: *>
56: *> \param[in] M
57: *> \verbatim
58: *> M is INTEGER
59: *> The number of rows of the matrix A. M >= 0.
60: *> \endverbatim
61: *>
62: *> \param[in] N
63: *> \verbatim
64: *> N is INTEGER
65: *> The number of columns of the matrix A. N >= 0.
66: *> \endverbatim
67: *>
68: *> \param[in] ALPHA
69: *> \verbatim
70: *> ALPHA is DOUBLE PRECISION
71: *> The constant to which the offdiagonal elements are to be set.
72: *> \endverbatim
73: *>
74: *> \param[in] BETA
75: *> \verbatim
76: *> BETA is DOUBLE PRECISION
77: *> The constant to which the diagonal elements are to be set.
78: *> \endverbatim
79: *>
80: *> \param[in,out] A
81: *> \verbatim
82: *> A is DOUBLE PRECISION array, dimension (LDA,N)
83: *> On exit, the leading m-by-n submatrix of A is set as follows:
84: *>
85: *> if UPLO = 'U', A(i,j) = ALPHA, 1<=i<=j-1, 1<=j<=n,
86: *> if UPLO = 'L', A(i,j) = ALPHA, j+1<=i<=m, 1<=j<=n,
87: *> otherwise, A(i,j) = ALPHA, 1<=i<=m, 1<=j<=n, i.ne.j,
88: *>
89: *> and, for all UPLO, A(i,i) = BETA, 1<=i<=min(m,n).
90: *> \endverbatim
91: *>
92: *> \param[in] LDA
93: *> \verbatim
94: *> LDA is INTEGER
95: *> The leading dimension of the array A. LDA >= max(1,M).
96: *> \endverbatim
97: *
98: * Authors:
99: * ========
100: *
101: *> \author Univ. of Tennessee
102: *> \author Univ. of California Berkeley
103: *> \author Univ. of Colorado Denver
104: *> \author NAG Ltd.
105: *
1.11 bertrand 106: *> \date September 2012
1.8 bertrand 107: *
108: *> \ingroup auxOTHERauxiliary
109: *
110: * =====================================================================
1.1 bertrand 111: SUBROUTINE DLASET( UPLO, M, N, ALPHA, BETA, A, LDA )
112: *
1.11 bertrand 113: * -- LAPACK auxiliary routine (version 3.4.2) --
1.1 bertrand 114: * -- LAPACK is a software package provided by Univ. of Tennessee, --
115: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.11 bertrand 116: * September 2012
1.1 bertrand 117: *
118: * .. Scalar Arguments ..
119: CHARACTER UPLO
120: INTEGER LDA, M, N
121: DOUBLE PRECISION ALPHA, BETA
122: * ..
123: * .. Array Arguments ..
124: DOUBLE PRECISION A( LDA, * )
125: * ..
126: *
127: * =====================================================================
128: *
129: * .. Local Scalars ..
130: INTEGER I, J
131: * ..
132: * .. External Functions ..
133: LOGICAL LSAME
134: EXTERNAL LSAME
135: * ..
136: * .. Intrinsic Functions ..
137: INTRINSIC MIN
138: * ..
139: * .. Executable Statements ..
140: *
141: IF( LSAME( UPLO, 'U' ) ) THEN
142: *
143: * Set the strictly upper triangular or trapezoidal part of the
144: * array to ALPHA.
145: *
146: DO 20 J = 2, N
147: DO 10 I = 1, MIN( J-1, M )
148: A( I, J ) = ALPHA
149: 10 CONTINUE
150: 20 CONTINUE
151: *
152: ELSE IF( LSAME( UPLO, 'L' ) ) THEN
153: *
154: * Set the strictly lower triangular or trapezoidal part of the
155: * array to ALPHA.
156: *
157: DO 40 J = 1, MIN( M, N )
158: DO 30 I = J + 1, M
159: A( I, J ) = ALPHA
160: 30 CONTINUE
161: 40 CONTINUE
162: *
163: ELSE
164: *
165: * Set the leading m-by-n submatrix to ALPHA.
166: *
167: DO 60 J = 1, N
168: DO 50 I = 1, M
169: A( I, J ) = ALPHA
170: 50 CONTINUE
171: 60 CONTINUE
172: END IF
173: *
174: * Set the first min(M,N) diagonal elements to BETA.
175: *
176: DO 70 I = 1, MIN( M, N )
177: A( I, I ) = BETA
178: 70 CONTINUE
179: *
180: RETURN
181: *
182: * End of DLASET
183: *
184: END
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