1 SUBROUTINE ZPOSV( UPLO, N, NRHS, A, LDA, B, LDB, INFO )
2 *
3 * -- LAPACK driver routine (version 3.3.1) --
4 * -- LAPACK is a software package provided by Univ. of Tennessee, --
5 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
6 * -- April 2011 --
7 *
8 * .. Scalar Arguments ..
9 CHARACTER UPLO
10 INTEGER INFO, LDA, LDB, N, NRHS
11 * ..
12 * .. Array Arguments ..
13 COMPLEX*16 A( LDA, * ), B( LDB, * )
14 * ..
15 *
16 * Purpose
17 * =======
18 *
19 * ZPOSV computes the solution to a complex system of linear equations
20 * A * X = B,
21 * where A is an N-by-N Hermitian positive definite matrix and X and B
22 * are N-by-NRHS matrices.
23 *
24 * The Cholesky decomposition is used to factor A as
25 * A = U**H* U, if UPLO = 'U', or
26 * A = L * L**H, if UPLO = 'L',
27 * where U is an upper triangular matrix and L is a lower triangular
28 * matrix. The factored form of A is then used to solve the system of
29 * equations A * X = B.
30 *
31 * Arguments
32 * =========
33 *
34 * UPLO (input) CHARACTER*1
35 * = 'U': Upper triangle of A is stored;
36 * = 'L': Lower triangle of A is stored.
37 *
38 * N (input) INTEGER
39 * The number of linear equations, i.e., the order of the
40 * matrix A. N >= 0.
41 *
42 * NRHS (input) INTEGER
43 * The number of right hand sides, i.e., the number of columns
44 * of the matrix B. NRHS >= 0.
45 *
46 * A (input/output) COMPLEX*16 array, dimension (LDA,N)
47 * On entry, the Hermitian matrix A. If UPLO = 'U', the leading
48 * N-by-N upper triangular part of A contains the upper
49 * triangular part of the matrix A, and the strictly lower
50 * triangular part of A is not referenced. If UPLO = 'L', the
51 * leading N-by-N lower triangular part of A contains the lower
52 * triangular part of the matrix A, and the strictly upper
53 * triangular part of A is not referenced.
54 *
55 * On exit, if INFO = 0, the factor U or L from the Cholesky
56 * factorization A = U**H *U or A = L*L**H.
57 *
58 * LDA (input) INTEGER
59 * The leading dimension of the array A. LDA >= max(1,N).
60 *
61 * B (input/output) COMPLEX*16 array, dimension (LDB,NRHS)
62 * On entry, the N-by-NRHS right hand side matrix B.
63 * On exit, if INFO = 0, the N-by-NRHS solution matrix X.
64 *
65 * LDB (input) INTEGER
66 * The leading dimension of the array B. LDB >= max(1,N).
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, the leading minor of order i of A is not
72 * positive definite, so the factorization could not be
73 * completed, and the solution has not been computed.
74 *
75 * =====================================================================
76 *
77 * .. External Functions ..
78 LOGICAL LSAME
79 EXTERNAL LSAME
80 * ..
81 * .. External Subroutines ..
82 EXTERNAL XERBLA, ZPOTRF, ZPOTRS
83 * ..
84 * .. Intrinsic Functions ..
85 INTRINSIC MAX
86 * ..
87 * .. Executable Statements ..
88 *
89 * Test the input parameters.
90 *
91 INFO = 0
92 IF( .NOT.LSAME( UPLO, 'U' ) .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
93 INFO = -1
94 ELSE IF( N.LT.0 ) THEN
95 INFO = -2
96 ELSE IF( NRHS.LT.0 ) THEN
97 INFO = -3
98 ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
99 INFO = -5
100 ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
101 INFO = -7
102 END IF
103 IF( INFO.NE.0 ) THEN
104 CALL XERBLA( 'ZPOSV ', -INFO )
105 RETURN
106 END IF
107 *
108 * Compute the Cholesky factorization A = U**H *U or A = L*L**H.
109 *
110 CALL ZPOTRF( UPLO, N, A, LDA, INFO )
111 IF( INFO.EQ.0 ) THEN
112 *
113 * Solve the system A*X = B, overwriting B with X.
114 *
115 CALL ZPOTRS( UPLO, N, NRHS, A, LDA, B, LDB, INFO )
116 *
117 END IF
118 RETURN
119 *
120 * End of ZPOSV
121 *
122 END
2 *
3 * -- LAPACK driver routine (version 3.3.1) --
4 * -- LAPACK is a software package provided by Univ. of Tennessee, --
5 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
6 * -- April 2011 --
7 *
8 * .. Scalar Arguments ..
9 CHARACTER UPLO
10 INTEGER INFO, LDA, LDB, N, NRHS
11 * ..
12 * .. Array Arguments ..
13 COMPLEX*16 A( LDA, * ), B( LDB, * )
14 * ..
15 *
16 * Purpose
17 * =======
18 *
19 * ZPOSV computes the solution to a complex system of linear equations
20 * A * X = B,
21 * where A is an N-by-N Hermitian positive definite matrix and X and B
22 * are N-by-NRHS matrices.
23 *
24 * The Cholesky decomposition is used to factor A as
25 * A = U**H* U, if UPLO = 'U', or
26 * A = L * L**H, if UPLO = 'L',
27 * where U is an upper triangular matrix and L is a lower triangular
28 * matrix. The factored form of A is then used to solve the system of
29 * equations A * X = B.
30 *
31 * Arguments
32 * =========
33 *
34 * UPLO (input) CHARACTER*1
35 * = 'U': Upper triangle of A is stored;
36 * = 'L': Lower triangle of A is stored.
37 *
38 * N (input) INTEGER
39 * The number of linear equations, i.e., the order of the
40 * matrix A. N >= 0.
41 *
42 * NRHS (input) INTEGER
43 * The number of right hand sides, i.e., the number of columns
44 * of the matrix B. NRHS >= 0.
45 *
46 * A (input/output) COMPLEX*16 array, dimension (LDA,N)
47 * On entry, the Hermitian matrix A. If UPLO = 'U', the leading
48 * N-by-N upper triangular part of A contains the upper
49 * triangular part of the matrix A, and the strictly lower
50 * triangular part of A is not referenced. If UPLO = 'L', the
51 * leading N-by-N lower triangular part of A contains the lower
52 * triangular part of the matrix A, and the strictly upper
53 * triangular part of A is not referenced.
54 *
55 * On exit, if INFO = 0, the factor U or L from the Cholesky
56 * factorization A = U**H *U or A = L*L**H.
57 *
58 * LDA (input) INTEGER
59 * The leading dimension of the array A. LDA >= max(1,N).
60 *
61 * B (input/output) COMPLEX*16 array, dimension (LDB,NRHS)
62 * On entry, the N-by-NRHS right hand side matrix B.
63 * On exit, if INFO = 0, the N-by-NRHS solution matrix X.
64 *
65 * LDB (input) INTEGER
66 * The leading dimension of the array B. LDB >= max(1,N).
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, the leading minor of order i of A is not
72 * positive definite, so the factorization could not be
73 * completed, and the solution has not been computed.
74 *
75 * =====================================================================
76 *
77 * .. External Functions ..
78 LOGICAL LSAME
79 EXTERNAL LSAME
80 * ..
81 * .. External Subroutines ..
82 EXTERNAL XERBLA, ZPOTRF, ZPOTRS
83 * ..
84 * .. Intrinsic Functions ..
85 INTRINSIC MAX
86 * ..
87 * .. Executable Statements ..
88 *
89 * Test the input parameters.
90 *
91 INFO = 0
92 IF( .NOT.LSAME( UPLO, 'U' ) .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
93 INFO = -1
94 ELSE IF( N.LT.0 ) THEN
95 INFO = -2
96 ELSE IF( NRHS.LT.0 ) THEN
97 INFO = -3
98 ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
99 INFO = -5
100 ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
101 INFO = -7
102 END IF
103 IF( INFO.NE.0 ) THEN
104 CALL XERBLA( 'ZPOSV ', -INFO )
105 RETURN
106 END IF
107 *
108 * Compute the Cholesky factorization A = U**H *U or A = L*L**H.
109 *
110 CALL ZPOTRF( UPLO, N, A, LDA, INFO )
111 IF( INFO.EQ.0 ) THEN
112 *
113 * Solve the system A*X = B, overwriting B with X.
114 *
115 CALL ZPOTRS( UPLO, N, NRHS, A, LDA, B, LDB, INFO )
116 *
117 END IF
118 RETURN
119 *
120 * End of ZPOSV
121 *
122 END