◆ zgtsv()

(Simple driver) Solution to system of linear equations AX = B for a complex tridiagonal matrix

Purpose: This routine solves the equation
A * X = B

where A is an n x n tridiagonal matrix, by Gaussian elimination with partial pivoting.
Note that the equation A^T*X = B may be solved by interchanging the order of the arguments du and dl.

Parameters

[in]	n	Order of the matrix A. (n >= 0) (If n = 0, returns without computation)
[in]	nrhs	Number of right hand sides, i.e., number of columns of the matrix B. (nrhs >= 0) (if nrhs = 0, returns without computation)
[in,out]	dl[]	Array dl[ldl] (ldl >= n - 1) [in] n-1 sub-diagonal elements of A. [out] n-2 elements of the second super-diagonal of the upper triangular matrix U from the LU factorization of A, in dl[0], ..., dl[n-3].
[in,out]	d[]	Array d[ld] (ld >= n) [in] Diagonal elements of A. [out] n diagonal elements of U.
[in,out]	du[]	Array du[ldu] (ldu >= n - 1) [in] n-1 super-diagonal elements of A. [out] n-1 elements of the first super-diagonal of U.
[in]	ldb	Leading dimension of the two dimensional array b[][]. (ldb >= max(1, n))
[in,out]	b[][]	Array b[lb][ldb] (lb >= nrhs) [in] n x nrhs matrix of right hand side matrix B. [out] If info = 0, n x nrhs solution matrix X.
[out]	info	= 0: Successful exit = -1: The argument n had an illegal value (n < 0) = -2: The argument nrhs had an illegal value (nrhs < 0) = -6: The argument ldb had an illegal value (ldb < max(1, n)) = i > 0: The i-th diagonal element of the factor U is exactly zero, and the solution has not been computed. The factorization has not been completed unless i = n.