1 /* ./src_f77/chpsv.f -- translated by f2c (version 20030320).
2 You must link the resulting object file with the libraries:
3 -lf2c -lm (in that order)
4 */
5
6 #include <punc/vf2c.h>
7
chpsv_(char * uplo,integer * n,integer * nrhs,complex * ap,integer * ipiv,complex * b,integer * ldb,integer * info,ftnlen uplo_len)8 /* Subroutine */ int chpsv_(char *uplo, integer *n, integer *nrhs, complex *
9 ap, integer *ipiv, complex *b, integer *ldb, integer *info, ftnlen
10 uplo_len)
11 {
12 /* System generated locals */
13 integer b_dim1, b_offset, i__1;
14
15 /* Local variables */
16 extern logical lsame_(char *, char *, ftnlen, ftnlen);
17 extern /* Subroutine */ int xerbla_(char *, integer *, ftnlen), chptrf_(
18 char *, integer *, complex *, integer *, integer *, ftnlen),
19 chptrs_(char *, integer *, integer *, complex *, integer *,
20 complex *, integer *, integer *, ftnlen);
21
22
23 /* -- LAPACK driver routine (version 3.0) -- */
24 /* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., */
25 /* Courant Institute, Argonne National Lab, and Rice University */
26 /* March 31, 1993 */
27
28 /* .. Scalar Arguments .. */
29 /* .. */
30 /* .. Array Arguments .. */
31 /* .. */
32
33 /* Purpose */
34 /* ======= */
35
36 /* CHPSV computes the solution to a complex system of linear equations */
37 /* A * X = B, */
38 /* where A is an N-by-N Hermitian matrix stored in packed format and X */
39 /* and B are N-by-NRHS matrices. */
40
41 /* The diagonal pivoting method is used to factor A as */
42 /* A = U * D * U**H, if UPLO = 'U', or */
43 /* A = L * D * L**H, if UPLO = 'L', */
44 /* where U (or L) is a product of permutation and unit upper (lower) */
45 /* triangular matrices, D is Hermitian and block diagonal with 1-by-1 */
46 /* and 2-by-2 diagonal blocks. The factored form of A is then used to */
47 /* solve the system of equations A * X = B. */
48
49 /* Arguments */
50 /* ========= */
51
52 /* UPLO (input) CHARACTER*1 */
53 /* = 'U': Upper triangle of A is stored; */
54 /* = 'L': Lower triangle of A is stored. */
55
56 /* N (input) INTEGER */
57 /* The number of linear equations, i.e., the order of the */
58 /* matrix A. N >= 0. */
59
60 /* NRHS (input) INTEGER */
61 /* The number of right hand sides, i.e., the number of columns */
62 /* of the matrix B. NRHS >= 0. */
63
64 /* AP (input/output) COMPLEX array, dimension (N*(N+1)/2) */
65 /* On entry, the upper or lower triangle of the Hermitian matrix */
66 /* A, packed columnwise in a linear array. The j-th column of A */
67 /* is stored in the array AP as follows: */
68 /* if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; */
69 /* if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n. */
70 /* See below for further details. */
71
72 /* On exit, the block diagonal matrix D and the multipliers used */
73 /* to obtain the factor U or L from the factorization */
74 /* A = U*D*U**H or A = L*D*L**H as computed by CHPTRF, stored as */
75 /* a packed triangular matrix in the same storage format as A. */
76
77 /* IPIV (output) INTEGER array, dimension (N) */
78 /* Details of the interchanges and the block structure of D, as */
79 /* determined by CHPTRF. If IPIV(k) > 0, then rows and columns */
80 /* k and IPIV(k) were interchanged, and D(k,k) is a 1-by-1 */
81 /* diagonal block. If UPLO = 'U' and IPIV(k) = IPIV(k-1) < 0, */
82 /* then rows and columns k-1 and -IPIV(k) were interchanged and */
83 /* D(k-1:k,k-1:k) is a 2-by-2 diagonal block. If UPLO = 'L' and */
84 /* IPIV(k) = IPIV(k+1) < 0, then rows and columns k+1 and */
85 /* -IPIV(k) were interchanged and D(k:k+1,k:k+1) is a 2-by-2 */
86 /* diagonal block. */
87
88 /* B (input/output) COMPLEX array, dimension (LDB,NRHS) */
89 /* On entry, the N-by-NRHS right hand side matrix B. */
90 /* On exit, if INFO = 0, the N-by-NRHS solution matrix X. */
91
92 /* LDB (input) INTEGER */
93 /* The leading dimension of the array B. LDB >= max(1,N). */
94
95 /* INFO (output) INTEGER */
96 /* = 0: successful exit */
97 /* < 0: if INFO = -i, the i-th argument had an illegal value */
98 /* > 0: if INFO = i, D(i,i) is exactly zero. The factorization */
99 /* has been completed, but the block diagonal matrix D is */
100 /* exactly singular, so the solution could not be */
101 /* computed. */
102
103 /* Further Details */
104 /* =============== */
105
106 /* The packed storage scheme is illustrated by the following example */
107 /* when N = 4, UPLO = 'U': */
108
109 /* Two-dimensional storage of the Hermitian matrix A: */
110
111 /* a11 a12 a13 a14 */
112 /* a22 a23 a24 */
113 /* a33 a34 (aij = conjg(aji)) */
114 /* a44 */
115
116 /* Packed storage of the upper triangle of A: */
117
118 /* AP = [ a11, a12, a22, a13, a23, a33, a14, a24, a34, a44 ] */
119
120 /* ===================================================================== */
121
122 /* .. External Functions .. */
123 /* .. */
124 /* .. External Subroutines .. */
125 /* .. */
126 /* .. Intrinsic Functions .. */
127 /* .. */
128 /* .. Executable Statements .. */
129
130 /* Test the input parameters. */
131
132 /* Parameter adjustments */
133 --ap;
134 --ipiv;
135 b_dim1 = *ldb;
136 b_offset = 1 + b_dim1;
137 b -= b_offset;
138
139 /* Function Body */
140 *info = 0;
141 if (! lsame_(uplo, "U", (ftnlen)1, (ftnlen)1) && ! lsame_(uplo, "L", (
142 ftnlen)1, (ftnlen)1)) {
143 *info = -1;
144 } else if (*n < 0) {
145 *info = -2;
146 } else if (*nrhs < 0) {
147 *info = -3;
148 } else if (*ldb < max(1,*n)) {
149 *info = -7;
150 }
151 if (*info != 0) {
152 i__1 = -(*info);
153 xerbla_("CHPSV ", &i__1, (ftnlen)6);
154 return 0;
155 }
156
157 /* Compute the factorization A = U*D*U' or A = L*D*L'. */
158
159 chptrf_(uplo, n, &ap[1], &ipiv[1], info, (ftnlen)1);
160 if (*info == 0) {
161
162 /* Solve the system A*X = B, overwriting B with X. */
163
164 chptrs_(uplo, n, nrhs, &ap[1], &ipiv[1], &b[b_offset], ldb, info, (
165 ftnlen)1);
166
167 }
168 return 0;
169
170 /* End of CHPSV */
171
172 } /* chpsv_ */
173
174