00001 /* ssysv.f -- translated by f2c (version 20061008). 00002 You must link the resulting object file with libf2c: 00003 on Microsoft Windows system, link with libf2c.lib; 00004 on Linux or Unix systems, link with .../path/to/libf2c.a -lm 00005 or, if you install libf2c.a in a standard place, with -lf2c -lm 00006 -- in that order, at the end of the command line, as in 00007 cc *.o -lf2c -lm 00008 Source for libf2c is in /netlib/f2c/libf2c.zip, e.g., 00009 00010 http://www.netlib.org/f2c/libf2c.zip 00011 */ 00012 00013 #include "f2c.h" 00014 #include "blaswrap.h" 00015 00016 /* Table of constant values */ 00017 00018 static integer c__1 = 1; 00019 static integer c_n1 = -1; 00020 00021 /* Subroutine */ int ssysv_(char *uplo, integer *n, integer *nrhs, real *a, 00022 integer *lda, integer *ipiv, real *b, integer *ldb, real *work, 00023 integer *lwork, integer *info) 00024 { 00025 /* System generated locals */ 00026 integer a_dim1, a_offset, b_dim1, b_offset, i__1; 00027 00028 /* Local variables */ 00029 integer nb; 00030 extern logical lsame_(char *, char *); 00031 extern /* Subroutine */ int xerbla_(char *, integer *); 00032 extern integer ilaenv_(integer *, char *, char *, integer *, integer *, 00033 integer *, integer *); 00034 integer lwkopt; 00035 logical lquery; 00036 extern /* Subroutine */ int ssytrf_(char *, integer *, real *, integer *, 00037 integer *, real *, integer *, integer *), ssytrs_(char *, 00038 integer *, integer *, real *, integer *, integer *, real *, 00039 integer *, integer *); 00040 00041 00042 /* -- LAPACK driver routine (version 3.2) -- */ 00043 /* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ 00044 /* November 2006 */ 00045 00046 /* .. Scalar Arguments .. */ 00047 /* .. */ 00048 /* .. Array Arguments .. */ 00049 /* .. */ 00050 00051 /* Purpose */ 00052 /* ======= */ 00053 00054 /* SSYSV computes the solution to a real system of linear equations */ 00055 /* A * X = B, */ 00056 /* where A is an N-by-N symmetric matrix and X and B are N-by-NRHS */ 00057 /* matrices. */ 00058 00059 /* The diagonal pivoting method is used to factor A as */ 00060 /* A = U * D * U**T, if UPLO = 'U', or */ 00061 /* A = L * D * L**T, if UPLO = 'L', */ 00062 /* where U (or L) is a product of permutation and unit upper (lower) */ 00063 /* triangular matrices, and D is symmetric and block diagonal with */ 00064 /* 1-by-1 and 2-by-2 diagonal blocks. The factored form of A is then */ 00065 /* used to solve the system of equations A * X = B. */ 00066 00067 /* Arguments */ 00068 /* ========= */ 00069 00070 /* UPLO (input) CHARACTER*1 */ 00071 /* = 'U': Upper triangle of A is stored; */ 00072 /* = 'L': Lower triangle of A is stored. */ 00073 00074 /* N (input) INTEGER */ 00075 /* The number of linear equations, i.e., the order of the */ 00076 /* matrix A. N >= 0. */ 00077 00078 /* NRHS (input) INTEGER */ 00079 /* The number of right hand sides, i.e., the number of columns */ 00080 /* of the matrix B. NRHS >= 0. */ 00081 00082 /* A (input/output) REAL array, dimension (LDA,N) */ 00083 /* On entry, the symmetric matrix A. If UPLO = 'U', the leading */ 00084 /* N-by-N upper triangular part of A contains the upper */ 00085 /* triangular part of the matrix A, and the strictly lower */ 00086 /* triangular part of A is not referenced. If UPLO = 'L', the */ 00087 /* leading N-by-N lower triangular part of A contains the lower */ 00088 /* triangular part of the matrix A, and the strictly upper */ 00089 /* triangular part of A is not referenced. */ 00090 00091 /* On exit, if INFO = 0, the block diagonal matrix D and the */ 00092 /* multipliers used to obtain the factor U or L from the */ 00093 /* factorization A = U*D*U**T or A = L*D*L**T as computed by */ 00094 /* SSYTRF. */ 00095 00096 /* LDA (input) INTEGER */ 00097 /* The leading dimension of the array A. LDA >= max(1,N). */ 00098 00099 /* IPIV (output) INTEGER array, dimension (N) */ 00100 /* Details of the interchanges and the block structure of D, as */ 00101 /* determined by SSYTRF. If IPIV(k) > 0, then rows and columns */ 00102 /* k and IPIV(k) were interchanged, and D(k,k) is a 1-by-1 */ 00103 /* diagonal block. If UPLO = 'U' and IPIV(k) = IPIV(k-1) < 0, */ 00104 /* then rows and columns k-1 and -IPIV(k) were interchanged and */ 00105 /* D(k-1:k,k-1:k) is a 2-by-2 diagonal block. If UPLO = 'L' and */ 00106 /* IPIV(k) = IPIV(k+1) < 0, then rows and columns k+1 and */ 00107 /* -IPIV(k) were interchanged and D(k:k+1,k:k+1) is a 2-by-2 */ 00108 /* diagonal block. */ 00109 00110 /* B (input/output) REAL array, dimension (LDB,NRHS) */ 00111 /* On entry, the N-by-NRHS right hand side matrix B. */ 00112 /* On exit, if INFO = 0, the N-by-NRHS solution matrix X. */ 00113 00114 /* LDB (input) INTEGER */ 00115 /* The leading dimension of the array B. LDB >= max(1,N). */ 00116 00117 /* WORK (workspace/output) REAL array, dimension (MAX(1,LWORK)) */ 00118 /* On exit, if INFO = 0, WORK(1) returns the optimal LWORK. */ 00119 00120 /* LWORK (input) INTEGER */ 00121 /* The length of WORK. LWORK >= 1, and for best performance */ 00122 /* LWORK >= max(1,N*NB), where NB is the optimal blocksize for */ 00123 /* SSYTRF. */ 00124 00125 /* If LWORK = -1, then a workspace query is assumed; the routine */ 00126 /* only calculates the optimal size of the WORK array, returns */ 00127 /* this value as the first entry of the WORK array, and no error */ 00128 /* message related to LWORK is issued by XERBLA. */ 00129 00130 /* INFO (output) INTEGER */ 00131 /* = 0: successful exit */ 00132 /* < 0: if INFO = -i, the i-th argument had an illegal value */ 00133 /* > 0: if INFO = i, D(i,i) is exactly zero. The factorization */ 00134 /* has been completed, but the block diagonal matrix D is */ 00135 /* exactly singular, so the solution could not be computed. */ 00136 00137 /* ===================================================================== */ 00138 00139 /* .. Local Scalars .. */ 00140 /* .. */ 00141 /* .. External Functions .. */ 00142 /* .. */ 00143 /* .. External Subroutines .. */ 00144 /* .. */ 00145 /* .. Intrinsic Functions .. */ 00146 /* .. */ 00147 /* .. Executable Statements .. */ 00148 00149 /* Test the input parameters. */ 00150 00151 /* Parameter adjustments */ 00152 a_dim1 = *lda; 00153 a_offset = 1 + a_dim1; 00154 a -= a_offset; 00155 --ipiv; 00156 b_dim1 = *ldb; 00157 b_offset = 1 + b_dim1; 00158 b -= b_offset; 00159 --work; 00160 00161 /* Function Body */ 00162 *info = 0; 00163 lquery = *lwork == -1; 00164 if (! lsame_(uplo, "U") && ! lsame_(uplo, "L")) { 00165 *info = -1; 00166 } else if (*n < 0) { 00167 *info = -2; 00168 } else if (*nrhs < 0) { 00169 *info = -3; 00170 } else if (*lda < max(1,*n)) { 00171 *info = -5; 00172 } else if (*ldb < max(1,*n)) { 00173 *info = -8; 00174 } else if (*lwork < 1 && ! lquery) { 00175 *info = -10; 00176 } 00177 00178 if (*info == 0) { 00179 if (*n == 0) { 00180 lwkopt = 1; 00181 } else { 00182 nb = ilaenv_(&c__1, "SSYTRF", uplo, n, &c_n1, &c_n1, &c_n1); 00183 lwkopt = *n * nb; 00184 } 00185 work[1] = (real) lwkopt; 00186 } 00187 00188 if (*info != 0) { 00189 i__1 = -(*info); 00190 xerbla_("SSYSV ", &i__1); 00191 return 0; 00192 } else if (lquery) { 00193 return 0; 00194 } 00195 00196 /* Compute the factorization A = U*D*U' or A = L*D*L'. */ 00197 00198 ssytrf_(uplo, n, &a[a_offset], lda, &ipiv[1], &work[1], lwork, info); 00199 if (*info == 0) { 00200 00201 /* Solve the system A*X = B, overwriting B with X. */ 00202 00203 ssytrs_(uplo, n, nrhs, &a[a_offset], lda, &ipiv[1], &b[b_offset], ldb, 00204 info); 00205 00206 } 00207 00208 work[1] = (real) lwkopt; 00209 00210 return 0; 00211 00212 /* End of SSYSV */ 00213 00214 } /* ssysv_ */