Annotation of rpl/lapack/lapack/dlat2s.f, revision 1.2
1.1 bertrand 1: SUBROUTINE DLAT2S( UPLO, N, A, LDA, SA, LDSA, INFO )
2: *
3: * -- LAPACK PROTOTYPE auxiliary routine (version 3.1.2) --
4: * -- LAPACK is a software package provided by Univ. of Tennessee, --
5: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
6: * May 2007
7: *
8: * .. Scalar Arguments ..
9: CHARACTER UPLO
10: INTEGER INFO, LDA, LDSA, N
11: * ..
12: * .. Array Arguments ..
13: REAL SA( LDSA, * )
14: DOUBLE PRECISION A( LDA, * )
15: * ..
16: *
17: * Purpose
18: * =======
19: *
20: * DLAT2S converts a DOUBLE PRECISION triangular matrix, SA, to a SINGLE
21: * PRECISION triangular matrix, A.
22: *
23: * RMAX is the overflow for the SINGLE PRECISION arithmetic
24: * DLAS2S checks that all the entries of A are between -RMAX and
25: * RMAX. If not the convertion is aborted and a flag is raised.
26: *
27: * This is an auxiliary routine so there is no argument checking.
28: *
29: * Arguments
30: * =========
31: *
32: * UPLO (input) CHARACTER*1
33: * = 'U': A is upper triangular;
34: * = 'L': A is lower triangular.
35: *
36: * N (input) INTEGER
37: * The number of rows and columns of the matrix A. N >= 0.
38: *
39: * A (input) DOUBLE PRECISION array, dimension (LDA,N)
40: * On entry, the N-by-N triangular coefficient matrix A.
41: *
42: * LDA (input) INTEGER
43: * The leading dimension of the array A. LDA >= max(1,N).
44: *
45: * SA (output) REAL array, dimension (LDSA,N)
46: * Only the UPLO part of SA is referenced. On exit, if INFO=0,
47: * the N-by-N coefficient matrix SA; if INFO>0, the content of
48: * the UPLO part of SA is unspecified.
49: *
50: * LDSA (input) INTEGER
51: * The leading dimension of the array SA. LDSA >= max(1,M).
52: *
53: * INFO (output) INTEGER
54: * = 0: successful exit.
55: * = 1: an entry of the matrix A is greater than the SINGLE
56: * PRECISION overflow threshold, in this case, the content
57: * of the UPLO part of SA in exit is unspecified.
58: *
59: * =========
60: *
61: * .. Local Scalars ..
62: INTEGER I, J
63: DOUBLE PRECISION RMAX
64: LOGICAL UPPER
65: * ..
66: * .. External Functions ..
67: REAL SLAMCH
68: LOGICAL LSAME
69: EXTERNAL SLAMCH, LSAME
70: * ..
71: * .. Executable Statements ..
72: *
73: RMAX = SLAMCH( 'O' )
74: UPPER = LSAME( UPLO, 'U' )
75: IF( UPPER ) THEN
76: DO 20 J = 1, N
77: DO 10 I = 1, J
78: IF( ( A( I, J ).LT.-RMAX ) .OR. ( A( I, J ).GT.RMAX ) )
79: + THEN
80: INFO = 1
81: GO TO 50
82: END IF
83: SA( I, J ) = A( I, J )
84: 10 CONTINUE
85: 20 CONTINUE
86: ELSE
87: DO 40 J = 1, N
88: DO 30 I = J, N
89: IF( ( A( I, J ).LT.-RMAX ) .OR. ( A( I, J ).GT.RMAX ) )
90: + THEN
91: INFO = 1
92: GO TO 50
93: END IF
94: SA( I, J ) = A( I, J )
95: 30 CONTINUE
96: 40 CONTINUE
97: END IF
98: 50 CONTINUE
99: *
100: RETURN
101: *
102: * End of DLAT2S
103: *
104: END
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