Solves a general tridiagonal system of linear equations using the LU factorization computed by ?dttrf.
call sdttrsv(uplo, trans, n, nrhs, dl, d, du, b, ldb, info)
call ddttrsv(uplo, trans, n, nrhs, dl, d, du, b, ldb, info)
call cdttrsv(uplo, trans, n, nrhs, dl, d, du, b, ldb, info)
call zdttrsv(uplo, trans, n, nrhs, dl, d, du, b, ldb, info)
The ?dttrsv routine solves one of the following systems of linear equations:
L*X = B, LT*X = B, or LH*X = B,
U*X = B, UT*X = B, or UH*X = B
with factors of the tridiagonal matrix A from the LU factorization computed by ?dttrf.
CHARACTER*1.
Specifies whether to solve with L or U.
CHARACTER. Must be 'N' or 'T' or 'C'.
Indicates the form of the equations:
If trans = 'N', then A*X=B is solved for X (no transpose).
If trans = 'T', then AT*X = B is solved for X (transpose).
If trans = 'C', then AH*X = B is solved for X (conjugate transpose).
INTEGER. The order of the matrix A(n ≥ 0).
INTEGER. The number of right-hand sides, that is, the number of columns in the matrix B(nrhs ≥ 0).
REAL for sdttrsv
DOUBLE PRECISION for ddttrsv
COMPLEX for cdttrsv
COMPLEX*16 for zdttrsv.
Arrays of DIMENSIONs: dl(n -1 ), d(n), du(n -1 ), b(ldb,nrhs).
The array dl contains the (n - 1) multipliers that define the matrix L from the LU factorization of A.
The array d contains n diagonal elements of the upper triangular matrix U from the LU factorization of A.
The array du contains the (n - 1) elements of the first super-diagonal of U.
On entry, the array b contains the right-hand side matrix B.
INTEGER. The leading dimension of the array b; ldb ≥ max(1, n).
Overwritten by the solution matrix X.
INTEGER. If info=0, the execution is successful.
If info = -i, the i-th parameter had an illegal value.