#include "blaswrap.h" #include "f2c.h" /* Subroutine */ int cgesv_(integer *n, integer *nrhs, complex *a, integer * lda, integer *ipiv, complex *b, integer *ldb, integer *info) { /* -- LAPACK driver routine (version 3.0) -- Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., Courant Institute, Argonne National Lab, and Rice University March 31, 1993 Purpose ======= CGESV computes the solution to a complex system of linear equations A * X = B, where A is an N-by-N matrix and X and B are N-by-NRHS matrices. The LU decomposition with partial pivoting and row interchanges is used to factor A as A = P * L * U, where P is a permutation matrix, L is unit lower triangular, and U is upper triangular. The factored form of A is then used to solve the system of equations A * X = B. Arguments ========= N (input) INTEGER The number of linear equations, i.e., the order of the matrix A. N >= 0. NRHS (input) INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0. A (input/output) COMPLEX array, dimension (LDA,N) On entry, the N-by-N coefficient matrix A. On exit, the factors L and U from the factorization A = P*L*U; the unit diagonal elements of L are not stored. LDA (input) INTEGER The leading dimension of the array A. LDA >= max(1,N). IPIV (output) INTEGER array, dimension (N) The pivot indices that define the permutation matrix P; row i of the matrix was interchanged with row IPIV(i). B (input/output) COMPLEX array, dimension (LDB,NRHS) On entry, the N-by-NRHS matrix of right hand side matrix B. On exit, if INFO = 0, the N-by-NRHS solution matrix X. LDB (input) INTEGER The leading dimension of the array B. LDB >= max(1,N). INFO (output) INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value > 0: if INFO = i, U(i,i) is exactly zero. The factorization has been completed, but the factor U is exactly singular, so the solution could not be computed. ===================================================================== Test the input parameters. Parameter adjustments */ /* System generated locals */ integer a_dim1, a_offset, b_dim1, b_offset, i__1; /* Local variables */ extern /* Subroutine */ int cgetrf_(integer *, integer *, complex *, integer *, integer *, integer *), xerbla_(char *, integer *), cgetrs_(char *, integer *, integer *, complex *, integer *, integer *, complex *, integer *, integer *); a_dim1 = *lda; a_offset = 1 + a_dim1 * 1; a -= a_offset; --ipiv; b_dim1 = *ldb; b_offset = 1 + b_dim1 * 1; b -= b_offset; /* Function Body */ *info = 0; if (*n < 0) { *info = -1; } else if (*nrhs < 0) { *info = -2; } else if (*lda < max(1,*n)) { *info = -4; } else if (*ldb < max(1,*n)) { *info = -7; } if (*info != 0) { i__1 = -(*info); xerbla_("CGESV ", &i__1); return 0; } /* Compute the LU factorization of A. */ cgetrf_(n, n, &a[a_offset], lda, &ipiv[1], info); if (*info == 0) { /* Solve the system A*X = B, overwriting B with X. */ cgetrs_("No transpose", n, nrhs, &a[a_offset], lda, &ipiv[1], &b[ b_offset], ldb, info); } return 0; /* End of CGESV */ } /* cgesv_ */