| SUBROUTINE ZGESVF( N, NRHS, A, LDA, IPIV, B, LDB, INFO ) |
| * |
| * -- LAPACK driver routine (version 3.1) -- |
| * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. |
| * November 2006 |
| * |
| * .. Scalar Arguments .. |
| INTEGER INFO, LDA, LDB, N, NRHS |
| * .. |
| * .. Array Arguments .. |
| INTEGER IPIV( * ) |
| COMPLEX*16 A( LDA, * ), B( LDB, * ) |
| * .. |
| * |
| * Purpose |
| * ======= |
| * |
| * ZGESV 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*16 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*16 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. |
| * |
| * ===================================================================== |
| * |
| * .. External Subroutines .. |
| EXTERNAL XERBLA, ZGETRF, ZGETRS |
| * .. |
| * .. Intrinsic Functions .. |
| INTRINSIC MAX |
| * .. |
| * .. Executable Statements .. |
| * |
| * Test the input parameters. |
| * |
| INFO = 0 |
| IF( N.LT.0 ) THEN |
| INFO = -1 |
| ELSE IF( NRHS.LT.0 ) THEN |
| INFO = -2 |
| ELSE IF( LDA.LT.MAX( 1, N ) ) THEN |
| INFO = -4 |
| ELSE IF( LDB.LT.MAX( 1, N ) ) THEN |
| INFO = -7 |
| END IF |
| IF( INFO.NE.0 ) THEN |
| CALL XERBLA( 'ZGESV ', -INFO ) |
| RETURN |
| END IF |
| * |
| * Compute the LU factorization of A. |
| * |
| CALL ZGETRF( N, N, A, LDA, IPIV, INFO ) |
| IF( INFO.EQ.0 ) THEN |
| * |
| * Solve the system A*X = B, overwriting B with X. |
| * |
| CALL ZGETRS( 'No transpose', N, NRHS, A, LDA, IPIV, B, LDB, |
| $ INFO ) |
| END IF |
| RETURN |
| * |
| * End of ZGESV |
| * |
| END |