Annotation of rpl/lapack/lapack/zsytri2.f, revision 1.2
1.1 bertrand 1: SUBROUTINE ZSYTRI2( UPLO, N, A, LDA, IPIV, WORK, LWORK, INFO )
2: *
3: * -- LAPACK routine (version 3.3.0) --
4: * -- LAPACK is a software package provided by Univ. of Tennessee, --
5: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
6: * November 2010
7: *
8: * -- Written by Julie Langou of the Univ. of TN --
9: *
10: * .. Scalar Arguments ..
11: CHARACTER UPLO
12: INTEGER INFO, LDA, LWORK, N
13: * ..
14: * .. Array Arguments ..
15: INTEGER IPIV( * )
16: DOUBLE COMPLEX A( LDA, * ), WORK( * )
17: * ..
18: *
19: * Purpose
20: * =======
21: *
22: * ZSYTRI2 computes the inverse of a complex symmetric indefinite matrix
23: * A using the factorization A = U*D*U**T or A = L*D*L**T computed by
24: * ZSYTRF. ZSYTRI2 sets the LEADING DIMENSION of the workspace
25: * before calling ZSYTRI2X that actually computes the inverse.
26: *
27: * Arguments
28: * =========
29: *
30: * UPLO (input) CHARACTER*1
31: * Specifies whether the details of the factorization are stored
32: * as an upper or lower triangular matrix.
33: * = 'U': Upper triangular, form is A = U*D*U**T;
34: * = 'L': Lower triangular, form is A = L*D*L**T.
35: *
36: * N (input) INTEGER
37: * The order of the matrix A. N >= 0.
38: *
39: * A (input/output) DOUBLE COMPLEX array, dimension (LDA,N)
40: * On entry, the NB diagonal matrix D and the multipliers
41: * used to obtain the factor U or L as computed by ZSYTRF.
42: *
43: * On exit, if INFO = 0, the (symmetric) inverse of the original
44: * matrix. If UPLO = 'U', the upper triangular part of the
45: * inverse is formed and the part of A below the diagonal is not
46: * referenced; if UPLO = 'L' the lower triangular part of the
47: * inverse is formed and the part of A above the diagonal is
48: * not referenced.
49: *
50: * LDA (input) INTEGER
51: * The leading dimension of the array A. LDA >= max(1,N).
52: *
53: * IPIV (input) INTEGER array, dimension (N)
54: * Details of the interchanges and the NB structure of D
55: * as determined by ZSYTRF.
56: *
57: * WORK (workspace) DOUBLE COMPLEX array, dimension (N+NB+1)*(NB+3)
58: *
59: * LWORK (input) INTEGER
60: * The dimension of the array WORK.
61: * WORK is size >= (N+NB+1)*(NB+3)
62: * If LDWORK = -1, then a workspace query is assumed; the routine
63: * calculates:
64: * - the optimal size of the WORK array, returns
65: * this value as the first entry of the WORK array,
66: * - and no error message related to LDWORK is issued by XERBLA.
67: *
68: * INFO (output) INTEGER
69: * = 0: successful exit
70: * < 0: if INFO = -i, the i-th argument had an illegal value
71: * > 0: if INFO = i, D(i,i) = 0; the matrix is singular and its
72: * inverse could not be computed.
73: *
74: * =====================================================================
75: *
76: * .. Local Scalars ..
77: LOGICAL UPPER, LQUERY
78: INTEGER MINSIZE, NBMAX
79: * ..
80: * .. External Functions ..
81: LOGICAL LSAME
82: INTEGER ILAENV
83: EXTERNAL LSAME, ILAENV
84: * ..
85: * .. External Subroutines ..
86: EXTERNAL ZSYTRI2X
87: * ..
88: * .. Executable Statements ..
89: *
90: * Test the input parameters.
91: *
92: INFO = 0
93: UPPER = LSAME( UPLO, 'U' )
94: LQUERY = ( LWORK.EQ.-1 )
95: * Get blocksize
96: NBMAX = ILAENV( 1, 'ZSYTRF', UPLO, N, -1, -1, -1 )
97: MINSIZE = (N+NBMAX+1)*(NBMAX+3)
98: *
99: IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
100: INFO = -1
101: ELSE IF( N.LT.0 ) THEN
102: INFO = -2
103: ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
104: INFO = -4
105: ELSE IF (LWORK .LT. MINSIZE .AND. .NOT.LQUERY ) THEN
106: INFO = -7
107: END IF
108: *
109: * Quick return if possible
110: *
111: *
112: IF( INFO.NE.0 ) THEN
113: CALL XERBLA( 'ZSYTRI2', -INFO )
114: RETURN
115: ELSE IF( LQUERY ) THEN
116: WORK(1)=(N+NBMAX+1)*(NBMAX+3)
117: RETURN
118: END IF
119: IF( N.EQ.0 )
120: $ RETURN
121:
122: CALL ZSYTRI2X( UPLO, N, A, LDA, IPIV, WORK, NBMAX, INFO )
123: RETURN
124: *
125: * End of ZSYTRI2
126: *
127: END
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