Annotation of rpl/lapack/lapack/dlat2s.f, revision 1.11
1.9 bertrand 1: *> \brief \b DLAT2S converts a double-precision triangular matrix to a single-precision triangular matrix.
1.7 bertrand 2: *
3: * =========== DOCUMENTATION ===========
4: *
5: * Online html documentation available at
6: * http://www.netlib.org/lapack/explore-html/
7: *
8: *> \htmlonly
9: *> Download DLAT2S + dependencies
10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlat2s.f">
11: *> [TGZ]</a>
12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlat2s.f">
13: *> [ZIP]</a>
14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlat2s.f">
15: *> [TXT]</a>
16: *> \endhtmlonly
17: *
18: * Definition:
19: * ===========
20: *
21: * SUBROUTINE DLAT2S( UPLO, N, A, LDA, SA, LDSA, INFO )
22: *
23: * .. Scalar Arguments ..
24: * CHARACTER UPLO
25: * INTEGER INFO, LDA, LDSA, N
26: * ..
27: * .. Array Arguments ..
28: * REAL SA( LDSA, * )
29: * DOUBLE PRECISION A( LDA, * )
30: * ..
31: *
32: *
33: *> \par Purpose:
34: * =============
35: *>
36: *> \verbatim
37: *>
38: *> DLAT2S converts a DOUBLE PRECISION triangular matrix, SA, to a SINGLE
39: *> PRECISION triangular matrix, A.
40: *>
41: *> RMAX is the overflow for the SINGLE PRECISION arithmetic
42: *> DLAS2S checks that all the entries of A are between -RMAX and
43: *> RMAX. If not the convertion is aborted and a flag is raised.
44: *>
45: *> This is an auxiliary routine so there is no argument checking.
46: *> \endverbatim
47: *
48: * Arguments:
49: * ==========
50: *
51: *> \param[in] UPLO
52: *> \verbatim
53: *> UPLO is CHARACTER*1
54: *> = 'U': A is upper triangular;
55: *> = 'L': A is lower triangular.
56: *> \endverbatim
57: *>
58: *> \param[in] N
59: *> \verbatim
60: *> N is INTEGER
61: *> The number of rows and columns of the matrix A. N >= 0.
62: *> \endverbatim
63: *>
64: *> \param[in] A
65: *> \verbatim
66: *> A is DOUBLE PRECISION array, dimension (LDA,N)
67: *> On entry, the N-by-N triangular coefficient matrix A.
68: *> \endverbatim
69: *>
70: *> \param[in] LDA
71: *> \verbatim
72: *> LDA is INTEGER
73: *> The leading dimension of the array A. LDA >= max(1,N).
74: *> \endverbatim
75: *>
76: *> \param[out] SA
77: *> \verbatim
78: *> SA is REAL array, dimension (LDSA,N)
79: *> Only the UPLO part of SA is referenced. On exit, if INFO=0,
80: *> the N-by-N coefficient matrix SA; if INFO>0, the content of
81: *> the UPLO part of SA is unspecified.
82: *> \endverbatim
83: *>
84: *> \param[in] LDSA
85: *> \verbatim
86: *> LDSA is INTEGER
87: *> The leading dimension of the array SA. LDSA >= max(1,M).
88: *> \endverbatim
89: *>
90: *> \param[out] INFO
91: *> \verbatim
92: *> INFO is INTEGER
93: *> = 0: successful exit.
94: *> = 1: an entry of the matrix A is greater than the SINGLE
95: *> PRECISION overflow threshold, in this case, the content
96: *> of the UPLO part of SA in exit is unspecified.
97: *> \endverbatim
98: *
99: * Authors:
100: * ========
101: *
102: *> \author Univ. of Tennessee
103: *> \author Univ. of California Berkeley
104: *> \author Univ. of Colorado Denver
105: *> \author NAG Ltd.
106: *
1.9 bertrand 107: *> \date September 2012
1.7 bertrand 108: *
109: *> \ingroup doubleOTHERauxiliary
110: *
111: * =====================================================================
1.1 bertrand 112: SUBROUTINE DLAT2S( UPLO, N, A, LDA, SA, LDSA, INFO )
113: *
1.9 bertrand 114: * -- LAPACK auxiliary routine (version 3.4.2) --
1.1 bertrand 115: * -- LAPACK is a software package provided by Univ. of Tennessee, --
116: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.9 bertrand 117: * September 2012
1.1 bertrand 118: *
119: * .. Scalar Arguments ..
120: CHARACTER UPLO
121: INTEGER INFO, LDA, LDSA, N
122: * ..
123: * .. Array Arguments ..
124: REAL SA( LDSA, * )
125: DOUBLE PRECISION A( LDA, * )
126: * ..
127: *
1.5 bertrand 128: * =====================================================================
1.1 bertrand 129: *
130: * .. Local Scalars ..
131: INTEGER I, J
132: DOUBLE PRECISION RMAX
133: LOGICAL UPPER
134: * ..
135: * .. External Functions ..
136: REAL SLAMCH
137: LOGICAL LSAME
138: EXTERNAL SLAMCH, LSAME
139: * ..
140: * .. Executable Statements ..
141: *
142: RMAX = SLAMCH( 'O' )
143: UPPER = LSAME( UPLO, 'U' )
144: IF( UPPER ) THEN
145: DO 20 J = 1, N
146: DO 10 I = 1, J
147: IF( ( A( I, J ).LT.-RMAX ) .OR. ( A( I, J ).GT.RMAX ) )
1.5 bertrand 148: $ THEN
1.1 bertrand 149: INFO = 1
150: GO TO 50
151: END IF
152: SA( I, J ) = A( I, J )
153: 10 CONTINUE
154: 20 CONTINUE
155: ELSE
156: DO 40 J = 1, N
157: DO 30 I = J, N
158: IF( ( A( I, J ).LT.-RMAX ) .OR. ( A( I, J ).GT.RMAX ) )
1.5 bertrand 159: $ THEN
1.1 bertrand 160: INFO = 1
161: GO TO 50
162: END IF
163: SA( I, J ) = A( I, J )
164: 30 CONTINUE
165: 40 CONTINUE
166: END IF
167: 50 CONTINUE
168: *
169: RETURN
170: *
171: * End of DLAT2S
172: *
173: END
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